PATENT DOCUMENT

Publication Number: US-11949462-B2
Application Number: US-202217892961-A
Country: US
Kind Code: B2

Title: Electronic devices with high frequency multiplexing capabilities

Abstract:
A communication system may an optical signal generator and a signal path. The generator may generate one or more optical local oscillator (LO) signals and an optical frequency comb. Optical paths and an optical demultiplexer may distribute the optical LO signal(s) and the frequency comb to photodiodes in one or more access points. The photodiodes may be coupled to antenna radiating elements. The optical paths may illuminate each photodiode using a signal pair that includes one of the optical LO signals and one of the carriers from the frequency comb. The photodiodes may convey wireless signals using the antenna radiating elements at frequencies given by the differences in frequency between the signals in the signal pairs. The radiating elements may concurrently convey the wireless signals with different external devices at different frequencies, with different devices at the same frequency, and/or with the same device at the same frequency.

Claims:
What is claimed is: 
     
       1. A communication system comprising:
 an optical signal generator configured to generate an optical local oscillator (LO) signal and an optical frequency comb that is offset in frequency from the optical LO signal; 
 an optical modulator configured to modulate wireless data onto the optical frequency comb; 
 an antenna radiating element; 
 a photodiode coupled to the antenna radiating element; and 
 an optical path configured to illuminate the photodiode with the optical LO signal and a portion of the optical frequency comb, the photodiode being configured to generate, based on the optical LO signal, the portion of the optical frequency comb, and a bias voltage applied to the photodiode, a current on the antenna radiating element that radiates wireless signals that include at least some of the wireless data. 
 
     
     
       2. The communication system of  claim 1 , wherein the optical frequency comb comprises a set of evenly spaced carriers that are modulated with the wireless data and the portion of the optical frequency comb comprises a carrier from the set of evenly spaced carriers. 
     
     
       3. The communication system of  claim 2 , further comprising:
 an additional antenna radiating element; 
 an additional photodiode coupled to the additional antenna radiating element; and 
 an additional optical path configured to illuminate the additional photodiode with the optical LO signal and an additional carrier from the set of evenly spaced carriers, the additional photodiode being configured to generate, based on the optical LO signal, the additional carrier, and the bias voltage applied to the additional photodiode, an additional current on the additional antenna radiating element and having a different current than the current on the antenna radiating element, the additional current on the additional antenna radiating element being configured to radiate additional wireless signals that include at least some of the wireless data. 
 
     
     
       4. The communication system of  claim 3 , wherein the antenna radiating element is configured to transmit the wireless signals to a first external device and the additional antenna radiating element is configured to concurrently transmit the additional wireless signals to a second external device. 
     
     
       5. The communication system of  claim 2 , wherein the optical signal generator is configured to generate an additional optical LO signal that is offset in frequency from the optical LO signal by a frequency gap, further comprising:
 an additional antenna radiating element; 
 an additional photodiode coupled to the additional antenna radiating element; and 
 an additional optical path configured to illuminate the additional photodiode with the additional optical LO signal and an additional carrier from the set of evenly spaced carriers, the additional carrier being separated in frequency from the carrier by the frequency gap and the additional photodiode being configured to generate, based on the additional optical LO signal, the additional carrier, and a bias voltage applied to the additional photodiode, an additional current on the additional antenna radiating element, the additional current on the additional antenna radiating element being configured to radiate additional wireless signals that include at least some of the wireless data. 
 
     
     
       6. The communication system of  claim 5 , wherein the antenna radiating element is configured to transmit the wireless signals to a first external device and the additional antenna radiating element is configured to concurrently transmit the additional wireless signals to a second external device that is spatially separated from the first external device. 
     
     
       7. The communication system of  claim 5 , wherein the antenna radiating element is configured to transmit the wireless signals to an external device and the additional antenna radiating element is configured to concurrently transmit the additional wireless signals to the external device. 
     
     
       8. The communication system of  claim 1 , further comprising:
 a first housing, wherein the optical signal generator and the optical modulator are disposed in the first housing; 
 a second housing, wherein the photodiode, the optical path, and the antenna radiating element are disposed in the second housing; and 
 an optical fiber coupled between the first housing and the second housing. 
 
     
     
       9. The communication system of  claim 1 , further comprising:
 an electronic device housing, wherein the optical signal generator, the optical modulator, the antenna radiating element, the photodiode, and the optical path are disposed in the electronic device housing. 
 
     
     
       10. A method of operating a communication system comprising:
 generating, using an optical signal generator, a first optical local oscillator (LO) signal and a set of evenly spaced optical carriers that are offset from the first optical LO signal; 
 modulating, using an optical modulator, wireless data onto the set of evenly spaced optically carriers to produce a set of evenly spaced modulated optical carriers; 
 conveying, using an optical fiber, the first optical LO signal and the set of evenly spaced modulated optical carriers to an optical demultiplexer; 
 demultiplexing, using the optical demultiplexer, the set of evenly spaced modulated optical carriers and providing the first optical LO signal and a first modulated optical carrier from the set of evenly spaced modulated optical carriers to a first photodiode; and 
 transmitting, using the first photodiode, first wireless signals at a first frequency over a first antenna radiating element using the first optical LO signal and the first modulated optical carrier. 
 
     
     
       11. The method of  claim 10 , further comprising:
 providing, using the optical demultiplexer, the first optical LO signal and a second modulated optical carrier from the set of evenly spaced modulated optical carriers to a second photodiode; and 
 transmitting, using the second photodiode, second wireless signals at a second frequency greater that is different from the first frequency over a second antenna radiating element using the first optical LO signal and the second modulated optical carrier concurrently with transmission of the first wireless signals by the first antenna radiating element. 
 
     
     
       12. The method of  claim 11 , wherein the first antenna radiating element is in a first phased antenna array and the second antenna radiating element is in a second phased antenna array, the method comprising:
 directing, using the first phased antenna array, the first wireless signals towards a first external device; and 
 directing, using the second phased antenna array, the second wireless signals towards a second external device. 
 
     
     
       13. The method of  claim 10 , further comprising:
 generating, using the optical signal generator, a second optical LO signal; 
 providing, using the optical demultiplexer, the second optical LO signal and a second modulated optical carrier from the set of evenly spaced modulated optical carriers to a second photodiode; and 
 transmitting, using the second photodiode, second wireless signals at the frequency over a second antenna radiating element using the second optical LO signal and the second modulated optical carrier concurrently with transmission of the first wireless signals by the first antenna radiating element. 
 
     
     
       14. The method of  claim 13 , wherein the second optical LO signal is offset from the first optical LO signal by a frequency gap and the second modulated optical carrier is offset from the first modulated optical carrier by the frequency gap. 
     
     
       15. The method of  claim 13 , wherein the first antenna radiating element is in a first phased antenna array and the second antenna radiating element is in a second phased antenna array, the method comprising:
 directing, using the first phased antenna array, the first wireless signals towards a first external device; and 
 directing, using the second phased antenna array, directing the second wireless signals towards a second external device. 
 
     
     
       16. An electronic device comprising:
 an optical signal generator configured to generate an optical local oscillator (LO) signal and a set of optical tones that are evenly spaced in frequency and that are offset in frequency from the optical LO signal, the set of optical tones having at least a first optical tone and a second optical tone; 
 a first photodiode coupled to a first antenna radiating element; 
 a second photodiode coupled to a second antenna radiating element; and 
 an optical splitter coupled to the optical signal generator through a first optical path, coupled to the first photodiode over a second optical path, and coupled to the second photodiode over a third optical path, the optical splitter being configured to transmit the optical LO signal and the first optical tone to the first photodiode and being configured to transmit the optical LO signal and the second optical tone to the second photodiode, the first photodiode and the first antenna radiating element being configured to convey first wireless signals at a first frequency greater using the optical LO signal and the first optical tone, and the second photodiode and the second antenna radiating element being configured to convey second wireless signals at a second frequency that is different from the first frequency using the optical LO signal and the second optical tone. 
 
     
     
       17. The electronic device of  claim 16 , wherein the first optical path comprises a first optical fiber, the second optical path comprises a second optical fiber, and the third optical path comprises a third optical fiber. 
     
     
       18. The electronic device of  claim 17 , further comprising:
 an optical modulator coupled between the first optical fiber and the optical signal generator, wherein the optical modulator is configured to modulate the set of optical tones using wireless data. 
 
     
     
       19. The electronic device of  claim 16 , wherein the first optical tone is offset in frequency from the optical LO signal by the first frequency and the second optical tone is offset in frequency from the optical LO signal by the second frequency. 
     
     
       20. The electronic device of  claim 16 , wherein the first photodiode comprises a first uni-travelling-carrier photodiode (UTC PD) and the second photodiode comprises a second UTC PD.

Description:
This application claims the benefit of U.S. Provisional Patent Application No. 63/246,739, filed Sep. 21, 2021, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This disclosure relates generally to electronic devices and, more particularly, to electronic devices with wireless circuitry. 
     BACKGROUND 
     Electronic devices are often provided with wireless capabilities. An electronic device with wireless capabilities has wireless circuitry that includes one or more antennas. The wireless circuitry is used to perform communications using radio-frequency signals conveyed by the antennas. 
     As software applications on electronic devices become more data-intensive over time, demand has grown for electronic devices that support wireless communications at higher data rates. However, the maximum data rate supported by electronic devices is limited by the frequency of the radio-frequency signals. In addition, it is often desirable for the electronic device to be able to communicate with multiple external devices at once. 
     SUMMARY 
     A wireless communication system may include one or more electronic devices that wirelessly communicate with one or more external devices. The system may include a central optical controller with an optical signal generator. The optical signal generator may generate an optical local oscillator (LO) signal or a set of optical LO signals that are evenly spaced by a frequency gap. The optical signal generator may also generate an optical frequency comb that is offset in frequency from the optical LO signal(s). The optical frequency comb may include a set of carriers (tones) that are evenly spaced by the frequency gap. 
     Optical paths and an optical demultiplexer may distribute the optical LO signal(s) and the optical frequency comb to photodiodes in one or more access points. The photodiodes may be coupled to antenna radiating elements. The optical paths may illuminate each photodiode using a signal pair that includes one of the optical LO signals and one of the carriers from the optical frequency comb. This may configure the photodiodes to convey wireless signals using the antenna radiating elements at frequencies given by the differences in frequency between the signals in the signal pairs. The wireless signals may be conveyed at frequencies greater than 100 GHz. The antenna radiating elements may concurrently convey the wireless signals with different external devices at different frequencies, with different devices at the same frequency (e.g., using different data streams), and/or with the same device at the same frequencies. Driving the photodiodes using portions of an optical frequency comb may minimize the size, cost, complexity, and power consumption of the central optical controller. 
     An aspect of the disclosure provides a communication system. The communication system can include an optical signal generator configured to generate an optical local oscillator (LO) signal and an optical frequency comb that is offset in frequency from the optical LO signal. The communication system can include an optical modulator configured to modulate wireless data onto the optical frequency comb. The communication system can include an antenna radiating element. The communication system can include a photodiode coupled to the antenna radiating element. The communication system can include an optical path configured to illuminate the photodiode with the optical LO signal and a portion of the optical frequency comb. The photodiode can be configured to generate, based on the optical LO signal, the portion of the optical frequency comb, and a bias voltage applied to the photodiode, a current at a frequency greater than or equal to 100 GHz on the antenna radiating element. The current on the antenna radiating element can be configured to radiate wireless signals that include at least some of the wireless data. 
     An aspect of the disclosure provides a method of operating a communication system. The method can include with an optical signal generator, generating a first optical local oscillator (LO) signal and a set of evenly spaced optical carriers that are offset from the first optical LO signal. The method can include with an optical modulator, modulating wireless data onto the set of evenly spaced optically carriers to produce a set of evenly spaced modulated optical carriers. The method can include with an optical fiber, conveying the first optical LO signal and the set of evenly spaced modulated optical carriers to an optical demultiplexer. The method can include with the optical demultiplexer, demultiplexing the set of evenly spaced modulated optical carriers and providing the first optical LO signal and a first modulated optical carrier from the set of evenly spaced modulated optical carriers to a first photodiode. The method can include with the first photodiode, transmitting first wireless signals at a first frequency greater than 100 GHz over a first antenna radiating element using the first optical LO signal and the first modulated optical carrier. 
     An aspect of the disclosure provides an electronic device. The electronic device can include an optical signal generator configured to generate an optical local oscillator (LO) signal and a set of optical tones that are evenly spaced in frequency and that are offset in frequency from the optical LO signal, the set of optical tones having at least a first optical tone and a second optical tone. The electronic device can include a first photodiode coupled to a first antenna radiating element. The electronic device can include a second photodiode coupled to a second antenna radiating element. The electronic device can include an optical splitter coupled to the optical signal generator through a first optical path, coupled to the first photodiode over a second optical path, and coupled to the second photodiode over a third optical path. The optical splitter can be configured to transmit the optical LO signal and the first optical tone to the first photodiode and being configured to transmit the optical LO signal and the second optical tone to the second photodiode. The first photodiode and the first antenna radiating element can be configured to convey first wireless signals at a first frequency greater than 100 GHz using the optical LO signal and the first optical tone. The second photodiode and the second antenna radiating element can be configured to convey second wireless signals at a second frequency that is different from the first frequency using the optical LO signal and the second optical tone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of an illustrative electronic device having wireless circuitry with at least one antenna that conveys wireless signals at frequencies greater than about 100 GHz in accordance with some embodiments. 
         FIG.  2    is a top view of an illustrative antenna that transmits wireless signals at frequencies greater than about 100 GHz based on optical local oscillator (LO) signals in accordance with some embodiments. 
         FIG.  3    is a top view showing how an illustrative antenna of the type shown in  FIG.  2    may convert received wireless signals at frequencies greater than about 100 GHz into intermediate frequency signals based on optical LO signals in accordance with some embodiments. 
         FIG.  4    is a top view showing how multiple antennas of the type shown in  FIGS.  2  and  3    may be stacked to cover multiple polarizations in accordance with some embodiments. 
         FIG.  5    is a top view showing how stacked antennas of the type shown in  FIG.  4    may be integrated into a phased antenna array for conveying wireless signals at frequencies greater than about 100 GHz within a corresponding signal beam. 
         FIG.  6    is a circuit diagram of illustrative wireless circuitry having an antenna that transmits wireless signals at frequencies greater than about 100 GHz and that receives wireless signals at frequencies greater than about 100 GHz for conversion to intermediate frequencies and then to the optical domain in accordance with some embodiments. 
         FIG.  7    is a circuit diagram of an illustrative phased antenna array that conveys wireless signals at frequencies greater than about 100 GHz within a corresponding signal beam in accordance with some embodiments. 
         FIG.  8    is a diagram showing how an illustrative central optical controller may provide optical signals to multiple access points that convey wireless signals at frequencies greater than about 100 GHz based on the optical signals in accordance with some embodiments. 
         FIG.  9    is a diagram showing how an illustrative central optical controller may generate an optical frequency comb signal that is distributed among multiple access points that convey wireless signals at frequencies greater than about 100 GHz based on an optical local oscillator and a respective optical carrier in the optical frequency comb signal in accordance with some embodiments. 
         FIG.  10    is a flow chart of illustrative operations involved in using multiple access points to transmit wireless signals at frequencies greater than about 100 GHz using an optical frequency comb signal in accordance with some embodiments. 
         FIG.  11    is a diagram showing how an illustrative central optical controller may provide optical signals to a single access point that conveys multiple streams of wireless signals at frequencies greater than about 100 GHz based on the optical signals in accordance with some embodiments. 
         FIG.  12    is a diagram showing how respective local oscillators and corresponding optical carriers from an optical frequency comb signal may be distributed across multiple photodiodes in an access point for conveying multiple streams of wireless signals at frequencies greater than about 100 GHz in accordance with some embodiments. 
         FIG.  13    is a flow chart of illustrative operations involved in using a single access point to transmit multiple streams of wireless signals at frequencies greater than about 100 GHz using an optical frequency comb signal in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic device  10  of  FIG.  1    (sometimes referred to herein as electro-optical device  10 ) may be a computing device such as a laptop computer, a desktop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses, goggles, or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic equipment with a display is mounted in a kiosk or automobile, a wireless internet-connected voice-controlled speaker, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, equipment that implements the functionality of two or more of these devices, or other electronic equipment. 
     As shown in the functional block diagram of  FIG.  1   , device  10  may include components located on or within an electronic device housing such as housing  12 . Housing  12 , which may sometimes be referred to as a case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, metal alloys, etc.), other suitable materials, or a combination of these materials. In some situations, parts or all of housing  12  may be formed from dielectric or other low-conductivity material (e.g., glass, ceramic, plastic, sapphire, etc.). In other situations, housing  12  or at least some of the structures that make up housing  12  may be formed from metal elements. 
     Device  10  may include control circuitry  14 . Control circuitry  14  may include storage such as storage circuitry  16 . Storage circuitry  16  may include hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid-state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Storage circuitry  16  may include storage that is integrated within device  10  and/or removable storage media. 
     Control circuitry  14  may include processing circuitry such as processing circuitry  18 . Processing circuitry  18  may be used to control the operation of device  10 . Processing circuitry  18  may include on one or more processors, microprocessors, microcontrollers, digital signal processors, host processors, baseband processor integrated circuits, application specific integrated circuits, central processing units (CPUs), graphics processing units (GPUs), etc. Control circuitry  14  may be configured to perform operations in device  10  using hardware (e.g., dedicated hardware or circuitry), firmware, and/or software. Software code for performing operations in device  10  may be stored on storage circuitry  16  (e.g., storage circuitry  16  may include non-transitory (tangible) computer readable storage media that stores the software code). The software code may sometimes be referred to as program instructions, software, data, instructions, or code. Software code stored on storage circuitry  16  may be executed by processing circuitry  18 . 
     Control circuitry  14  may be used to run software on device  10  such as satellite navigation applications, internet browsing applications, voice-over-internet-protocol (VOIP) telephone call applications, email applications, media playback applications, operating system functions, etc. To support interactions with external equipment, control circuitry  14  may be used in implementing communications protocols. Communications protocols that may be implemented using control circuitry  14  include internet protocols, wireless local area network (WLAN) protocols (e.g., IEEE 802.11 protocols—sometimes referred to as Wi-Fi®), protocols for other short-range wireless communications links such as the Bluetooth® protocol or other wireless personal area network (WPAN) protocols, IEEE 802.11ad protocols (e.g., ultra-wideband protocols), cellular telephone protocols (e.g., 3G protocols, 4G (LTE) protocols, 3GPP Fifth Generation (5G) New Radio (NR) protocols, Sixth Generation (6G) protocols, sub-THz protocols, THz protocols, etc.), antenna diversity protocols, satellite navigation system protocols (e.g., global positioning system (GPS) protocols, global navigation satellite system (GLONASS) protocols, etc.), antenna-based spatial ranging protocols, optical communications protocols, or any other desired communications protocols. Each communications protocol may be associated with a corresponding radio access technology (RAT) that specifies the physical connection methodology used in implementing the protocol. 
     Device  10  may include input-output circuitry  20 . Input-output circuitry  20  may include input-output devices  22 . Input-output devices  22  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  22  may include user interface devices, data port devices, and other input-output components. For example, input-output devices  22  may include touch sensors, displays (e.g., touch-sensitive and/or force-sensitive displays), light-emitting components such as displays without touch sensor capabilities, buttons (mechanical, capacitive, optical, etc.), scrolling wheels, touch pads, key pads, keyboards, microphones, cameras, buttons, speakers, status indicators, audio jacks and other audio port components, digital data port devices, motion sensors (accelerometers, gyroscopes, and/or compasses that detect motion), capacitance sensors, proximity sensors, magnetic sensors, force sensors (e.g., force sensors coupled to a display to detect pressure applied to the display), temperature sensors, etc. In some configurations, keyboards, headphones, displays, pointing devices such as trackpads, mice, and joysticks, and other input-output devices may be coupled to device  10  using wired or wireless connections (e.g., some of input-output devices  22  may be peripherals that are coupled to a main processing unit or other portion of device  10  via a wired or wireless link). 
     Input-output circuitry  20  may include wireless circuitry  24  to support wireless communications. Wireless circuitry  24  (sometimes referred to herein as wireless communications circuitry  24 ) may include one or more antennas  30 . 
     Wireless circuitry  24  may also include transceiver circuitry  26 . Transceiver circuitry  26  may include transmitter circuitry, receiver circuitry, modulator circuitry, demodulator circuitry (e.g., one or more modems), radio-frequency circuitry, one or more radios, intermediate frequency circuitry, optical transmitter circuitry, optical receiver circuitry, optical light sources, other optical components, baseband circuitry (e.g., one or more baseband processors), amplifier circuitry, clocking circuitry such as one or more local oscillators and/or phase-locked loops, memory, one or more registers, filter circuitry, switching circuitry, analog-to-digital converter (ADC) circuitry, digital-to-analog converter (DAC) circuitry, radio-frequency transmission lines, optical fibers, and/or any other circuitry for transmitting and/or receiving wireless signals using antennas  30 . The components of transceiver circuitry  26  may be implemented on one integrated circuit, chip, system-on-chip (SOC), die, printed circuit board, substrate, or package, or the components of transceiver circuitry  26  may be distributed across two or more integrated circuits, chips, SOCs, printed circuit boards, substrates, and/or packages. 
     The example of  FIG.  1    is merely illustrative. While control circuitry  14  is shown separately from wireless circuitry  24  in the example of  FIG.  1    for the sake of clarity, wireless circuitry  24  may include processing circuitry (e.g., one or more processors) that forms a part of processing circuitry  18  and/or storage circuitry that forms a part of storage circuitry  16  of control circuitry  14  (e.g., portions of control circuitry  14  may be implemented on wireless circuitry  24 ). As an example, control circuitry  14  may include baseband circuitry (e.g., one or more baseband processors), digital control circuitry, analog control circuitry, and/or other control circuitry that forms part of wireless circuitry  24 . The baseband circuitry may, for example, access a communication protocol stack on control circuitry  14  (e.g., storage circuitry  20 ) to: perform user plane functions at a PHY layer, MAC layer, RLC layer, PDCP layer, SDAP layer, and/or PDU layer, and/or to perform control plane functions at the PHY layer, MAC layer, RLC layer, PDCP layer, RRC, layer, and/or non-access stratum layer. 
     Transceiver circuitry  26  may be coupled to each antenna  30  in wireless circuitry  24  over a respective signal path  28 . Each signal path  28  may include one or more radio-frequency transmission lines, waveguides, optical fibers, and/or any other desired lines/paths for conveying wireless signals between transceiver circuitry  26  and antenna  30 . Antennas  30  may be formed using any desired antenna structures for conveying wireless signals. For example, antennas  30  may include antennas with resonating elements that are formed from dipole antenna structures, planar dipole antenna structures (e.g., bowtie antenna structures), slot antenna structures, loop antenna structures, patch antenna structures, inverted-F antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipoles, hybrids of these designs, etc. Filter circuitry, switching circuitry, impedance matching circuitry, and/or other antenna tuning components may be adjusted to adjust the frequency response and wireless performance of antennas  30  over time. 
     If desired, two or more of antennas  30  may be integrated into a phased antenna array (sometimes referred to herein as a phased array antenna) in which each of the antennas conveys wireless signals with a respective phase and magnitude that is adjusted over time so the wireless signals constructively and destructively interfere to produce (form) a signal beam in a given pointing direction. The term “convey wireless signals” as used herein means the transmission and/or reception of the wireless signals (e.g., for performing unidirectional and/or bidirectional wireless communications with external wireless communications equipment). Antennas  30  may transmit the wireless signals by radiating the signals into free space (or to free space through intervening device structures such as a dielectric cover layer). Antennas  30  may additionally or alternatively receive the wireless signals from free space (e.g., through intervening devices structures such as a dielectric cover layer). The transmission and reception of wireless signals by antennas  30  each involve the excitation or resonance of antenna currents on an antenna resonating (radiating) element in the antenna by the wireless signals within the frequency band(s) of operation of the antenna. 
     Transceiver circuitry  26  may use antenna(s)  30  to transmit and/or receive wireless signals that convey wireless communications data between device  10  and external wireless communications equipment (e.g., one or more other devices such as device  10 , a wireless access point or base station, etc.). The wireless communications data may be conveyed bidirectionally or unidirectionally. The wireless communications data may, for example, include data that has been encoded into corresponding data packets such as wireless data associated with a telephone call, streaming media content, internet browsing, wireless data associated with software applications running on device  10 , email messages, etc. 
     Additionally or alternatively, wireless circuitry  24  may use antenna(s)  30  to perform wireless sensing operations. The sensing operations may allow device  10  to detect (e.g., sense or identify) the presence, location, orientation, and/or velocity (motion) of objects external to device  10 . Control circuitry  14  may use the detected presence, location, orientation, and/or velocity of the external objects to perform any desired device operations. As examples, control circuitry  14  may use the detected presence, location, orientation, and/or velocity of the external objects to identify a corresponding user input for one or more software applications running on device  10  such as a gesture input performed by the user&#39;s hand(s) or other body parts or performed by an external stylus, gaming controller, head-mounted device, or other peripheral devices or accessories, to determine when one or more antennas  30  needs to be disabled or provided with a reduced maximum transmit power level (e.g., for satisfying regulatory limits on radio-frequency exposure), to determine how to steer (form) a radio-frequency signal beam produced by antennas  30  for wireless circuitry  24  (e.g., in scenarios where antennas  30  include a phased array of antennas  30 ), to map or model the environment around device  10  (e.g., to produce a software model of the room where device  10  is located for use by an augmented reality application, gaming application, map application, home design application, engineering application, etc.), to detect the presence of obstacles in the vicinity of (e.g., around) device  10  or in the direction of motion of the user of device  10 , etc. 
     Wireless circuitry  24  may transmit and/or receive wireless signals within corresponding frequency bands of the electromagnetic spectrum (sometimes referred to herein as communications bands or simply as “bands”). The frequency bands handled by communications circuitry  26  may include wireless local area network (WLAN) frequency bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network (WPAN) frequency bands such as the 2.4 GHz Bluetooth® band or other WPAN communications bands, cellular telephone frequency bands (e.g., bands from about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range 1 (FR1) bands below 10 GHz, 5G New Radio Frequency Range 2 (FR2) bands between 20 and 60 GHz, etc.), other centimeter or millimeter wave frequency bands between 10-100 GHz, near-field communications frequency bands (e.g., at 13.56 MHz), satellite navigation frequency bands (e.g., a GPS band from 1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) frequency bands that operate under the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols, communications bands under the family of 3GPP wireless communications standards, communications bands under the IEEE 802.XX family of standards, and/or any other desired frequency bands of interest. 
     Over time, software applications on electronic devices such as device  10  have become more and more data intensive. Wireless circuitry on the electronic devices therefore needs to support data transfer at higher and higher data rates. In general, the data rates supported by the wireless circuitry are proportional to the frequency of the wireless signals conveyed by the wireless circuitry (e.g., higher frequencies can support higher data rates than lower frequencies). Wireless circuitry  24  may convey centimeter and millimeter wave signals to support relatively high data rates (e.g., because centimeter and millimeter wave signals are at relatively high frequencies between around 10 GHz and 100 GHz). However, the data rates supported by centimeter and millimeter wave signals may still be insufficient to meet all the data transfer needs of device  10 . To support even higher data rates such as data rates up to 5-10 Gbps or higher, wireless circuitry  24  may convey wireless signals at frequencies greater than 100 GHz. 
     As shown in  FIG.  1   , wireless circuitry  24  may transmit wireless signals  32  and may receive wireless signals  34  at frequencies greater than around 100 GHz. Wireless signals  32  and  34  may sometimes be referred to herein as tremendously high frequency (THF) signals  32  and  34 , sub-THz signals  32  and  34 , THz signals  32  and  34 , or sub-millimeter wave signals  32  and  34 . THF signals  32  and  34  may be at sub-THz or THz frequencies such as frequencies between 100 GHz and 1 THz, between 100 GHz and 10 THz, between 100 GHz and 2 THz, between 200 GHz and 1 THz, between 300 GHz and 1 THz, between 300 GHz and 2 THz, between 300 GHz and 10 THz, between 100 GHz and 800 GHz, between 200 GHz and 1.5 THz, etc. (e.g., within a sub-THz, THz, THF, or sub-millimeter frequency band such as a 6G frequency band). The high data rates supported by these frequencies may be leveraged by device  10  to perform cellular telephone voice and/or data communications (e.g., while supporting spatial multiplexing to provide further data bandwidth), to perform spatial ranging operations such as radar operations to detect the presence, location, and/or velocity of objects external to device  10 , to perform automotive sensing (e.g., with enhanced security), to perform health/body monitoring on a user of device  10  or another person, to perform gas or chemical detection, to form a high data rate wireless connection between device  10  and another device or peripheral device (e.g., to form a high data rate connection between a display driver on device  10  and a display that displays ultra-high resolution video), to form a remote radio head (e.g., a flexible high data rate connection), to form a THF chip-to-chip connection within device  10  that supports high data rates (e.g., where one antenna  30  on a first chip in device  10  transmits THF signals  32  to another antenna  30  on a second chip in device  10 ), and/or to perform any other desired high data rate operations. 
     Space is at a premium within electronic devices such as device  10 . In some scenarios, different antennas  30  are used to transmit THF signals  32  than are used to receive THF signals  34 . However, handling transmission of THF signals  32  and reception of THF signals  34  using different antennas  30  can consume an excessive amount of space and other resources within device  10  because two antennas  30  and signal paths  28  would be required to handle both transmission and reception. To minimize space and resource consumption within device  10 , the same antenna  30  and signal path  28  may be used to both transmit THF signals  32  and to receive THF signals  34 . If desired, multiple antennas  30  in wireless circuitry  24  may transmit THF signals  32  and may receive THF signals  34 . The antennas may be integrated into a phased antenna array that transmits THF signals  32  and that receives THF signals  34  within a corresponding signal beam oriented in a selected beam pointing direction. 
     It can be challenging to incorporate components into wireless circuitry  24  that support wireless communications at these high frequencies. If desired, transceiver circuitry  26  and signal paths  28  may include optical components that convey optical signals to support the transmission of THF signals  32  and the reception of THF signals  34  in a space and resource-efficient manner. The optical signals may be used in transmitting THF signals  32  at THF frequencies and in receiving THF signals  34  at THF frequencies. 
       FIG.  2    is a diagram of an illustrative antenna  30  that may be used to both transmit THF signals  32  and to receive THF signals  34  using optical signals. Antenna  30  may include one or more antenna radiating (resonating) elements such as radiating (resonating) element arms  36 . In the example of  FIG.  2   , antenna  30  is a planar dipole antenna (sometimes referred to as a “bowtie” antenna) having two opposing radiating element arms  36  (e.g., bowtie arms or dipole arms). This is merely illustrative and, in general, antenna  30  may be any type of antenna having any desired antenna radiating element architecture. 
     As shown in  FIG.  2   , antenna  30  includes a photodiode (PD)  42  coupled between radiating element arms  36 . Electronic devices that include antennas  30  with photodiodes  42  such as device  10  may sometimes also be referred to as electro-optical devices (e.g., electro-optical device  10 ). Photodiode  42  may be a programmable photodiode. An example in which photodiode  42  is a programmable uni-travelling-carrier photodiode (UTC PD) is described herein as an example. Photodiode  42  may therefore sometimes be referred to herein as UTC PD  42  or programmable UTC PD  42 . This is merely illustrative and, in general, photodiode  42  may include any desired type of adjustable/programmable photodiode or component that converts electromagnetic energy at optical frequencies to current at THF frequencies on radiating element arms  36  and/or vice versa. Each radiating element arm  36  may, for example, have a first edge at UTC PD  42  and a second edge opposite the first edge that is wider than the first edge (e.g., in implementations where antenna  30  is a bowtie antenna). Other radiating elements may be used if desired. 
     UTC PD  42  may have a bias terminal  38  that receives one or more control signals V BIAS . Control signals V BIAS  may include bias voltages provided at one or more voltage levels and/or other control signals for controlling the operation of UTC PD  42  such as impedance adjustment control signals for adjusting the output impedance of UTC PD  42 . Control circuitry  14  ( FIG.  1   ) may provide (e.g., apply, supply, assert, etc.) control signals V BIAS  at different settings (e.g., values, magnitudes, etc.) to dynamically control (e.g., program or adjust) the operation of UTC PD  42  over time. For example, control signals V BIAS  may be used to control whether antenna  30  transmits THF signals  32  or receives THF signals  34 . When control signals V BIAS  include a bias voltage asserted at a first level or magnitude, antenna  30  may be configured to transmit THF signals  32 . When control signals V BIAS  include a bias voltage asserted at a second level or magnitude, antenna  30  may be configured to receive THF signals  34 . In the example of  FIG.  2   , control signals V BIAS  include the bias voltage asserted at the first level to configure antenna  30  to transmit THF signals  32 . If desired, control signals V BIAS  may also be adjusted to control the waveform of the THF signals (e.g., as a squaring function that preserves the modulation of incident optical signals, a linear function, etc.), to perform gain control on the signals conveyed by antenna  30 , and/or to adjust the output impedance of UTC PD  42 . 
     As shown in  FIG.  2   , UTC PD  42  may be optically coupled to optical path  40 . Optical path  40  may include one or more optical fibers or waveguides. UTC PD  42  may receive optical signals from transceiver circuitry  26  ( FIG.  1   ) over optical path  40 . The optical signals may include a first optical local oscillator (LO) signal LO 1  and a second optical local oscillator signal LO 2 . Optical local oscillator signals LO 1  and LO 2  may be generated by light sources in transceiver circuitry  26  ( FIG.  1   ). Optical local oscillator signals LO 1  and LO 2  may be at optical wavelengths (e.g., between 400 nm and 700 nm), ultra-violet wavelengths (e.g., near-ultra-violet or extreme ultraviolet wavelengths), and/or infrared wavelengths (e.g., near-infrared wavelengths, mid-infrared wavelengths, or far-infrared wavelengths). Optical local oscillator signal LO 2  may be offset in wavelength from optical local oscillator signal LO 1  by a wavelength offset X. Wavelength offset X may be equal to the wavelength of the THF signals conveyed by antenna  30  (e.g., between 100 GHz and 1 THz (1000 GHz), between 100 GHz and 2 THz, between 300 GHz and 800 GHz, between 300 GHz and 1 THz, between 300 and 400 GHz, etc.). 
     During signal transmission, wireless data (e.g., wireless data packets, symbols, frames, etc.) may be modulated onto optical local oscillator signal LO 2  to produce modulated optical local oscillator signal LO 2 ′. If desired, optical local oscillator signal LO 1  may be provided with an optical phase shift S. Optical path  40  may illuminate UTC PD  42  with optical local oscillator signal LO 1  (plus the optical phase shift S when applied) and modulated optical local oscillator signal LO 2 ′. If desired, lenses or other optical components may be interposed between optical path  40  and UTC PD  42  to help focus the optical local oscillator signals onto UTC PD  42 . 
     UTC PD  42  may convert optical local oscillator signal LO 1  and modulated local oscillator signal LO 2 ′ (e.g., beats between the two optical local oscillator signals) into antenna currents that run along the perimeter of radiating element arms  36 . The frequency of the antenna currents is equal to the frequency difference between local oscillator signal LO 1  and modulated local oscillator signal LO 2 ′. The antenna currents may radiate (transmit) THF signals  32  into free space. Control signal V BIAS  may control UTC PD  42  to convert the optical local oscillator signals into antenna currents on radiating element arms  36  while preserving the modulation and thus the wireless data on modulated local oscillator signal LO 2 ′ (e.g., by applying a squaring function to the signals). THF signals  32  will thereby carry the modulated wireless data for reception and demodulation by external wireless communications equipment. 
       FIG.  3    is a diagram showing how antenna  30  may receive THF signals  34  (e.g., after changing the setting of control signals V BIAS  into a reception state from the transmission state of  FIG.  2   ). As shown in  FIG.  3   , THF signals  34  may be incident upon antenna radiating element arms  36 . The incident THF signals  34  may produce antenna currents that flow around the perimeter of radiating element arms  36 . UTC PD  42  may use optical local oscillator signal LO 1  (plus the optical phase shift S when applied), optical local oscillator signal LO 2  (e.g., without modulation), and control signals V BIAS  (e.g., a bias voltage asserted at the second level) to convert the received THF signals  34  into intermediate frequency signals SIGIF that are output onto intermediate frequency signal path  44 . 
     The frequency of intermediate frequency signals SIGIF may be equal to the frequency of THF signals  34  minus the difference between the frequency of optical local oscillator signal LO 1  and the frequency of optical local oscillator signal LO 2 . As an example, intermediate frequency signals SIGIF may be at lower frequencies than THF signals  32  and  34  such as centimeter or millimeter wave frequencies between 10 GHz and 100 GHz, between 30 GHz and 80 GHz, around 60 GHz, etc. If desired, transceiver circuitry  26  ( FIG.  1   ) may change the frequency of optical local oscillator signal LO 1  and/or optical local oscillator signal LO 2  when switching from transmission to reception or vice versa. UTC PD  42  may preserve the data modulation of THF signals  34  in intermediate signals SIGIF. A receiver in transceiver circuitry  26  ( FIG.  1   ) may demodulate intermediate frequency signals SIGIF (e.g., after further downconversion) to recover the wireless data from THF signals  34 . In another example, wireless circuitry  24  may convert intermediate frequency signals SIGIF to the optical domain before recovering the wireless data. In yet another example, intermediate frequency signal path  44  may be omitted and UTC PD  42  may convert THF signals  34  into the optical domain for subsequent demodulation and data recovery (e.g., in a sideband of the optical signal). 
     The antenna  30  of  FIGS.  2  and  3    may support transmission of THF signals  32  and reception of THF signals  34  with a given polarization (e.g., a linear polarization such as a vertical polarization). If desired, wireless circuitry  24  ( FIG.  1   ) may include multiple antennas  30  for covering different polarizations.  FIG.  4    is a diagram showing one example of how wireless circuitry  24  may include multiple antennas  30  for covering different polarizations. 
     As shown in  FIG.  4   , the wireless circuitry may include a first antenna  30  such as antenna  30 V for covering a first polarization (e.g., a first linear polarization such as a vertical polarization) and may include a second antenna  30  such as antenna  30 H for covering a second polarization different from or orthogonal to the first polarization (e.g., a second linear polarization such as a horizontal polarization). Antenna  30 V may have a UTC PD  42  such as UTC PD  42 V coupled between a corresponding pair of radiating element arms  36 . Antenna  30 H may have a UTC PD  42  such as UTC PD  42 H coupled between a corresponding pair of radiating element arms  36  oriented non-parallel (e.g., orthogonal) to the radiating element arms  36  in antenna  30 V. This may allow antennas  30 V and  30 H to transmit THF signals  32  with respective (orthogonal) polarizations and may allow antennas  30 V and  30 H to receive THF signals  32  with respective (orthogonal) polarizations. 
     To minimize space within device  10 , antenna  30 V may be vertically stacked over or under antenna  30 H (e.g., where UTC PD  42 V partially or completely overlaps UTC PD  42 H). In this example, antennas  30 V and  30 H may both be formed on the same substrate such as a rigid or flexible printed circuit board. The substrate may include multiple stacked dielectric layers (e.g., layers of ceramic, epoxy, flexible printed circuit board material, rigid printed circuit board material, etc.). The radiating element arms  36  in antenna  30 V may be formed on a separate layer of the substrate than the radiating element arms  36  in antenna  30 H or the radiating element arms  36  in antenna  30 V may be formed on the same layer of the substrate as the radiating element arms  36  in antenna  30 H. UTC PD  42 V may be formed on the same layer of the substrate as UTC PD  42 H or UTC PD  42 V may be formed on a separate layer of the substrate than UTC PD  42 H. UTC PD  42 V may be formed on the same layer of the substrate as the radiating element arms  36  in antenna  30 V or may be formed on a separate layer of the substrate as the radiating element arms  36  in antenna  30 V. UTC PD  42 H may be formed on the same layer of the substrate as the radiating element arms  36  in antenna  30 H or may be formed on a separate layer of the substrate as the radiating element arms  36  in antenna  30 H. 
     If desired, antennas  30  or antennas  30 H and  30 V of  FIG.  4    may be integrated within a phased antenna array.  FIG.  5    is a diagram showing one example of how antennas  30 H and  30 V may be integrated within a phased antenna array. As shown in  FIG.  5   , device  10  may include a phased antenna array  46  of stacked antennas  30 H and  30 V arranged in a rectangular grid of rows and columns. Each of the antennas in phased antenna array  46  may be formed on the same substrate. This is merely illustrative. In general, phased antenna array  46  (sometimes referred to as a phased array antenna) may include any desired number of antennas  30 V and  30 H (or non-stacked antennas  30 ) arranged in any desired pattern. Each of the antennas in phased antenna array  46  may be provided with a respective optical phase shift S ( FIGS.  2  and  3   ) that configures the antennas to collectively transmit THF signals  32  and/or receive THF signals  34  that sum to form a signal beam of THF signals in a desired beam pointing direction. The beam pointing direction may be selected to point the signal beam towards external communications equipment, towards a desired external object, away from an external object, etc. 
     Phased antenna array  46  may occupy relatively little space within device  10 . For example, each antenna  30 V/ 30 H may have a length  48  (e.g., as measured from the end of one radiating element arm to the opposing end of the opposite radiating element arm). Length  48  may be approximately equal to one-half the wavelength of THF signals  32  and  34 . For example, length  48  may be as small as 0.5 mm or less. Each UTC-PD  42  in phased antenna array  46  may occupy a lateral area of 100 square microns or less. This may allow phased antenna array  46  to occupy very little area within device  10 , thereby allowing the phased antenna array to be integrated within different portions of device  10  while still allowing other space for device components. The examples of  FIGS.  2 - 5    are merely illustrative and, in general, each antenna may have any desired antenna radiating element architecture. 
       FIG.  6    is a circuit diagram showing how a given antenna  30  and signal path  28  ( FIG.  1   ) may be used to both transmit THF signals  32  and receive THF signals  34  based on optical local oscillator signals. In the example of  FIG.  6   , UTC PD  42  converts received THF signals  34  into intermediate frequency signals SIGIF that are then converted to the optical domain for recovering the wireless data from the received THF signals. 
     As shown in  FIG.  6   , wireless circuitry  24  may include transceiver circuitry  26  coupled to antenna  30  over signal path  28  (e.g., an optical signal path sometimes referred to herein as optical signal path  28 ). UTC PD  42  may be coupled between the radiating element arm(s)  36  of antenna  30  and signal path  28 . Transceiver circuitry  26  may include optical components  68 , amplifier circuitry such as power amplifier  76 , and digital-to-analog converter (DAC)  74 . Optical components  68  may include an optical receiver such as optical receiver  72  and optical local oscillator (LO) light sources (emitters)  70 . LO light sources  70  may include two or more light sources such as laser light sources, laser diodes, optical phase locked loops, or other optical emitters that emit light (e.g., optical local oscillator signals LO 1  and LO 2 ) at respective wavelengths. If desired, LO light sources  70  may include a single light source and may include optical components for splitting the light emitted by the light source into different wavelengths. Signal path  28  may be coupled to optical components  68  over optical path  66 . Optical path  66  may include one or more optical fibers and/or waveguides. 
     Signal path  28  may include an optical splitter such as optical splitter (OS)  54 , optical paths such as optical path  64  and optical path  62 , an optical combiner such as optical combiner (OC)  52 , and optical path  40 . Optical path  62  may be an optical fiber or waveguide. Optical path  64  may be an optical fiber or waveguide. Optical splitter  54  may have a first (e.g., input) port coupled to optical path  66 , a second (e.g., output) port coupled to optical path  62 , and a third (e.g., output) port coupled to optical path  64 . Optical path  64  may couple optical splitter  54  to a first (e.g., input) port of optical combiner  52 . Optical path  62  may couple optical splitter  54  to a second (e.g., input) port of optical combiner  52 . Optical combiner  52  may have a third (e.g., output) port coupled to optical path  40 . 
     An optical phase shifter such as optical phase shifter  80  may be (optically) interposed on or along optical path  64 . An optical modulator such as optical modulator  56  may be (optically) interposed on or along optical path  62 . Optical modulator  56  may be, for example, a Mach-Zehnder modulator (MZM) and may therefore sometimes be referred to herein as MZM  56 . MZM  56  includes a first optical arm (branch)  60  and a second optical arm (branch)  58  interposed in parallel along optical path  62 . Propagating optical local oscillator signal LO 2  along arms  60  and  58  of MZM  56  may, in the presence of a voltage signal applied to one or both arms, allow different optical phase shifts to be imparted on each arm before recombining the signal at the output of the MZM (e.g., where optical phase modulations produced on the arms are converted to intensity modulations at the output of MZM  56 ). When the voltage applied to MZM  56  includes wireless data, MZM  56  may modulate the wireless data onto optical local oscillator signal LO 2 . If desired, the phase shifting performed at MZM  56  may be used to perform beam forming/steering in addition to or instead of optical phase shifter  80 . MZM  56  may receive one or more bias voltages W BIAS  (sometimes referred to herein as bias signals W BIAS ) applied to one or both of arms  58  and  60 . Control circuitry  14  ( FIG.  1   ) may provide bias voltage W BIAS  with different magnitudes to place MZM  56  into different operating modes (e.g., operating modes that suppress optical carrier signals, operating modes that do not suppress optical carrier signals, etc.). 
     Intermediate frequency signal path  44  may couple UTC PD  42  to MZM  56  (e.g., arm  60 ). An amplifier such as low noise amplifier  83  may be interposed on intermediate frequency signal path  44 . Intermediate frequency signal path  44  may be used to pass intermediate frequency signals SIGIF from UTC PD  42  to MZM  56 . DAC  74  may have an input coupled to up-conversion circuitry, modulator circuitry, and/or baseband circuitry in a transmitter of transceiver circuitry  26 . DAC  74  may receive digital data to transmit over antenna  30  and may convert the digital data to the analog domain (e.g., as data DAT). DAC  74  may have an output coupled to transmit data path  78 . Transmit data path  78  may couple DAC  74  to MZM  56  (e.g., arm  60 ). Each of the components along signal path  28  may allow the same antenna  30  to both transmit THF signals  32  and receive THF signals  34  (e.g., using the same components along signal path  28 ), thereby minimizing space and resource consumption within device  10 . 
     LO light sources  70  may produce (emit) optical local oscillator signals LO 1  and LO 2  (e.g., at different wavelengths that are separated by the wavelength of THF signals  32 / 34 ). Optical components  68  may include lenses, waveguides, optical couplers, optical fibers, and/or other optical components that direct the emitted optical local oscillator signals LO 1  and LO 2  towards optical splitter  54  via optical path  66 . Optical splitter  54  may split the optical signals on optical path  66  (e.g., by wavelength) to output optical local oscillator signal LO 1  onto optical path  64  while outputting optical local oscillator signal LO 2  onto optical path  62 . 
     Control circuitry  14  ( FIG.  1   ) may provide phase control signals CTRL to optical phase shifter  80 . Phase control signals CTRL may control optical phase shifter  80  to apply optical phase shift S to the optical local oscillator signal LO 1  on optical path  64 . Phase shift S may be selected to steer a signal beam of THF signals  32 / 34  in a desired pointing direction. Optical phase shifter  80  may pass the phase-shifted optical local oscillator signal LO 1  (denoted as LO 1 +S) to optical combiner  52 . Signal beam steering is performed in the optical domain (e.g., using optical phase shifter  80 ) rather than in the THF domain because there are no satisfactory phase shifting circuit components that operate at frequencies as high as the frequencies of THF signals  32  and  34 . Optical combiner  52  may receive optical local oscillator signal LO 2  over optical path  62 . Optical combiner  52  may combine optical local oscillator signals LO 1  and LO 2  onto optical path  40 , which directs the optical local oscillator signals onto UTC PD  42  for use during signal transmission or reception. 
     During transmission of THF signals  32 , DAC  74  may receive digital wireless data (e.g., data packets, frames, symbols, etc.) for transmission over THF signals  32 . DAC  74  may convert the digital wireless data to the analog domain and may output (transmit) the data onto transmit data path  78  as data DAT (e.g., for transmission via antenna  30 ). Power amplifier  76  may amplify data DAT. Transmit data path  78  may pass data DAT to MZM  56  (e.g., arm  60 ). MZM  56  may modulate data DAT onto optical local oscillator signal LO 2  to produce modulated optical local oscillator signal LO 2 ′ (e.g., an optical local oscillator signal at the frequency/wavelength of optical local oscillator signal LO 2  but that is modulated to include the data identified by data DAT). Optical combiner  52  may combine optical local oscillator signal LO 1  with modulated optical local oscillator signal LO 2 ′ at optical path  40 . 
     Optical path  40  may illuminate UTC PD  42  with (using) optical local oscillator signal LO 1  (e.g., with the phase shift S applied by optical phase shifter  80 ) and modulated optical local oscillator signal LO 2 ′. Control circuitry  14  ( FIG.  1   ) may apply a control signal V BIAS  to UTC PD  42  that configures antenna  30  for the transmission of THF signals  32 . UTC PD  42  may convert optical local oscillator signal LO 1  and modulated optical local oscillator signal LO 2 ′ into antenna currents on radiating element arm(s)  36  at the frequency of THF signals  32  (e.g., while programmed for transmission using control signal V BIAS ). The antenna currents on radiating element arm(s)  36  may radiate THF signals  32 . The frequency of THF signals  32  is given by the difference in frequency between optical local oscillator signal LO 1  and modulated optical local oscillator signal LO 2 ′. Control signals V BIAS  may control UTC PD  42  to preserve the modulation from modulated optical local oscillator signal LO 2 ′ in the radiated THF signals  32 . External equipment that receives THF signals  32  will thereby be able to extract data DAT from the THF signals  32  transmitted by antenna  30 . 
     During reception of THF signals  34 , MZM  56  does not modulate any data onto optical local oscillator signal LO 2 . Optical path  40  therefore illuminates UTC PD  42  with optical local oscillator signal LO 1  (e.g., with phase shift S) and optical local oscillator signal LO 2 . Control circuitry  14  ( FIG.  1   ) may apply a control signal VBIAS (e.g., a bias voltage) to UTC PD  42  that configures antenna  30  for the receipt of THF signals  32 . UTC PD  42  may use optical local oscillator signals LO 1  and LO 2  to convert the received THF signals  34  into intermediate frequency signals SIGIF output onto intermediate frequency signal path  44  (e.g., while programmed for reception using bias voltage VBIAS¬). Intermediate frequency signals SIGIF may include the modulated data from the received THF signals  34 . Low noise amplifier  83  may amplify intermediate frequency signals SIGIF, which are then provided to MZM  56  (e.g., arm  60 ). MZM  56  may convert intermediate frequency signals SIGIF to the optical domain as optical signals LOrx (e.g., by modulating the data in intermediate frequency signals SIGIF onto one of the optical local oscillator signals) and may pass the optical signals to optical receiver  72  in optical components  68 , as shown by arrow  63  (e.g., via optical paths  62  and  66  or other optical paths). Control circuitry  14  ( FIG.  1   ) may use optical receiver  72  to convert optical signals LOrx to other formats and to recover (demodulate) the data carried by THF signals  34  from the optical signals. In this way, the same antenna  30  and signal path  28  may be used for both the transmission and reception of THF signals while also performing beam steering operations. 
     The example of  FIG.  6    in which intermediate frequency signals SIGIF are converted to the optical domain is merely illustrative. If desired, transceiver circuitry  26  may receive and demodulate intermediate frequency signals SIGIF without first passing the signals to the optical domain. For example, transceiver circuitry  26  may include an analog-to-digital converter (ADC), intermediate frequency signal path  44  may be coupled to an input of the ADC rather than to MZM  56 , and the ADC may convert intermediate frequency signals SIGIF to the digital domain. As another example, intermediate frequency signal path  44  may be omitted and control signals V BIAS  may control UTC PD  42  to directly sample THF signals  34  with optical local oscillator signals LO 1  and LO 2  to the optical domain. As an example, UTC PD  42  may use the received THF signals  34  and control signals V BIAS  to produce an optical signal on optical path  40 . The optical signal may have an optical carrier with sidebands that are separated from the optical carrier by a fixed frequency offset (e.g., 30-100 GHz, 60 GHz, 50-70 GHz, 10-100 GHz, etc.). The sidebands may be used to carry the modulated data from the received THF signals  34 . Signal path  28  may direct (propagate) the optical signal produced by UTC PD  42  to optical receiver  72  in optical components  68  (e.g., via optical paths  40 ,  64 ,  62 ,  66 ,  63 , and/or other optical paths). Control circuitry  14  ( FIG.  1   ) may use optical receiver  72  to convert the optical signal to other formats and to recover (demodulate) the data carried by THF signals  34  from the optical signal (e.g., from the sidebands of the optical signal). 
       FIG.  7    is a circuit diagram showing one example of how multiple antennas  30  may be integrated into a phased antenna array  88  that conveys THF signals over a corresponding signal beam. In the example of  FIG.  7   , MZMs  56 , intermediate frequency signal paths  44 , data paths  78 , and optical receiver  72  of  FIG.  6    have been omitted for the sake of clarity. Each of the antennas in phased antenna array  88  may alternatively sample received THF signals directly into the optical domain or may pass intermediate frequency signals SIGIF to ADCs in transceiver circuitry  26 . 
     As shown in  FIG.  7   , phased antenna array  88  includes N antennas  30  such as a first antenna  30 - 0 , a second antenna  30 - 1 , and an Nth antenna  30 -(N−1). Each of the antennas  30  in phased antenna array  88  may be coupled to optical components  68  via a respective optical signal path (e.g., optical signal path  28  of  FIG.  6   ). Each of the N signal paths may include a respective optical combiner  52  coupled to the UTC PD  42  of the corresponding antenna  30  (e.g., the UTC PD  42  in antenna  30 - 0  may be coupled to optical combiner  52 - 0 , the UTC PD  42  in antenna  30 - 1  may be coupled to optical combiner  52 - 1 , the UTC PD  42  in antenna  30 -(N−1) may be coupled to optical combiner  52 -(N−1), etc.). Each of the N signal paths may also include a respective optical path  62  and a respective optical path  64  coupled to the corresponding optical combiner  52  (e.g., optical paths  64 - 0  and  62 - 0  may be coupled to optical combiner  52 - 0 , optical paths  64 - 1  and  62 - 1  may be coupled to optical combiner  52 - 1 , optical paths  64 -(N−1) and  62 -(N−1) may be coupled to optical combiner  52 -(N−1), etc.). 
     Optical components  68  may include LO light sources  70  such as a first LO light source  70 A and a second LO light source  70 B. The optical signal paths for each of the antennas  30  in phased antenna array  88  may share one or more optical splitters  54  such as a first optical splitter  54 A and a second optical splitter  54 B. LO light source  70 A may generate (e.g., produce, emit, transmit, etc.) first optical local oscillator signal LO 1  and may provide first optical local oscillator signal LO 1  to optical splitter  54 A via optical path  66 A. Optical splitter  54 A may distribute first optical local oscillator signal LO 1  to each of the UTC PDs  42  in phased antenna array  88  over optical paths  64  (e.g., optical paths  64 - 0 ,  64 - 1 ,  64 -(N−1), etc.). Similarly, LO light source  70 B may generate (e.g., produce, emit, transmit, etc.) second optical local oscillator signal LO 2  and may provide second optical local oscillator signal LO 2  to optical splitter  54 B via optical path  66 B. Optical splitter  54 B may distribute second optical local oscillator signal LO 2  to each of the UTC PDs  42  in phased antenna array  88  over optical paths  62  (e.g., optical paths  62 - 0 ,  62 - 1 ,  62 -(N−1), etc.). 
     A respective optical phase shifter  80  may be interposed along (on) each optical path  64  (e.g., a first optical phase shifter  80 - 0  may be interposed along optical path  64 - 0 , a second optical phase shifter  80 - 1  may be interposed along optical path  64 - 1 , an Nth optical phase shifter  80 -(N−1) may be interposed along optical path  64 -(N−1), etc.). Each optical phase shifter  80  may receive a control signal CTRL that controls the phase S provided to optical local oscillator signal LO 1  by that optical phase shifter (e.g., first optical phase shifter  80 - 0  may impart an optical phase shift of zero degrees/radians to the optical local oscillator signal LO 1  provided to antenna  30 - 0 , second optical phase shifter  80 - 1  may impart an optical phase shift of Δϕ to the optical local oscillator signal LO 1  provided to antenna  30 - 1 , Nth optical phase shifter  80 -(N−1) may impart an optical phase shift of (N−1)Δϕ to the optical local oscillator signal LO 1  provided to antenna  30 -(N−1), etc.). By adjusting the phase S imparted by each of the N optical phase shifters  80 , control circuitry  14  ( FIG.  1   ) may control each of the antennas  30  in phased antenna array  88  to transmit THF signals  32  and/or to receive THF signals  34  within a formed signal beam  83 . Signal beam  83  may be oriented in a particular beam pointing direction (angle)  84  (e.g., the direction of peak gain of signal beam  83 ). The THF signals conveyed by phased antenna array  88  may have wavefronts  86  that are orthogonal to beam pointing direction  84 . Control circuitry  14  may adjust beam pointing direction  84  over time to point towards external communications equipment or an external object or to point away from external objects, as examples. The example of  FIG.  7    only illustrates THF signal transmission using antennas  30  for the sake of clarity. If desired, the circuitry of  FIG.  7    may be modified to additionally or alternatively receive THF signals (e.g., optical paths such as optical path  63  of  FIG.  6    may be added to couple each optical path  62  of  FIG.  7    to one or more optical receivers, intermediate frequency signals may be passed to a receiver, etc.). 
     Antenna radiating element arm(s)  36  and UTC PD  42  ( FIG.  6   ) may sometimes be referred to herein collectively as access point (AP)  45  (e.g., a THF access point). In some implementations, a single access point  45  is used to communicate with a single external device (e.g., another device such as device  10 , a wireless base station or access point, or other wireless (THF) communications equipment). If desired, transceiver  26  may use multiple access points distributed across one or more locations to concurrently communicate with one or more external devices over one or more streams of wireless signals (e.g., THF signals  32  and  34  of  FIG.  1   ). 
       FIG.  8    is a diagram showing one example of how multiple access points  45  may use THF signals to communicate with multiple external devices. As shown in  FIG.  8   , wireless communications system  95  (sometimes referred to herein as THF system  95 , wireless system  95 , communications system  95 , or simply as system  95 ) may include a set of M access points  45  (e.g., a first access point  45 - 1 , an Mth access point  45 -M, etc.). Each access point  45  may include one or more respective UTC PDs  42  ( FIG.  6   ) and one or more antenna radiating element arms  36  (e.g., a set of antenna radiating element arms  36  arranged in a corresponding phased antenna array or antenna panel). 
     Wireless communications system  95  may also include a centralized optical controller such as central optical controller  90 . Central optical controller  90  may sometimes also be referred to herein as central office  90 , central chip  90 , optical controller  90 , or optical processor  90 . Central optical controller  90  may include control circuitry such as control circuitry  14  of  FIG.  1   . The components of wireless circuitry  24  of  FIG.  6    may be distributed between access points  45  and central optical controller  90  of  FIG.  8   . For example, central optical controller  90  may include transceiver  26  and signal path  28  of  FIG.  6   . 
     Central optical controller  90  may be communicably coupled to each of the M access points  45  over optical signal paths. As shown in  FIG.  8   , central optical controller  90  may be coupled to optical splitter/combiner  94  over optical path  92 . Optical splitter/combiner  94  may also sometimes be referred to herein as an optical demultiplexer/multiplexer. Optical path  92  may include one or more optical fibers and/or waveguides. Optical splitter/combiner  94  may couple optical path  62  to each of the M access points  45  over a respective optical path  96  (e.g., optical splitter/combiner  94  may be coupled to access point  45 - 1  over optical path  96 - 1 , may be coupled to access point  45 -M over optical path  96 -M, etc.). Each optical path  96  include one or more optical fibers and/or waveguides. In this way, optical signal path  92 , optical splitter/combiner  94 , and optical signal paths  96  may form optical path  40  of  FIG.  6    for each of the M access points  45  in wireless communications system  95 , for example. 
     Central optical controller  90  may be co-located with access points  45  or may be disposed at a location separated from access points  45 . For example, central optical controller  90 , optical path  92 , optical splitter/combiner  94 , and access points  45  may all be enclosed within an electronic device housing such as housing  106  (e.g., a housing such as housing  12  of  FIG.  1   ). When configured in this way, central optical controller  90 , optical path  92 , optical splitter/combiner  94 , and access points  45  may all form components of a corresponding device  10  (e.g., a single laptop computer, cellular telephone, tablet computer, wristwatch device, portable media player, home entertainment console, desktop computer, gaming controller, head-mounted device, etc.). In these examples, access points  45  may be distributed across multiple locations on device  10  (e.g., in respective corners of the device housing, at different sides of the device housing, etc.). 
     As another example, central optical controller  90  may be enclosed within a first housing such as housing  100  (e.g., a housing such as housing  12  of  FIG.  1   ) whereas each access point  45  is enclosed within a respective housing  102  (e.g., a housing such as housing  12  of  FIG.  1   ). If desired, central optical controller  90 , optical path  92 , and optical splitter/combiner  94  may be enclosed within a first housing such as housing  104  (e.g., a housing such as housing  12  of  FIG.  1   ) that is separate from the housing(s) that include access points  45 . When configured in this way, central optical controller  90  may be located within a first device  10  whereas each of the access points  45  is located in a different respective device  10 , for example. If desired, two or more (e.g., all) of the access points  45  may be mounted within the same (shared) housing. In these configurations, the two or more access points  45  (e.g., all of the access points  45 ) may be located within a single device  10  that is separate from the device  10  that includes central optical controller  90 . 
     In other words, wireless communications system  95  may be located within a single device  10  or may be distributed across multiple devices  10 . In examples where the components of wireless communications system  95  are located within a single device  10 , access points  45  may be distributed across one or more locations in the device that are separate from central optical controller  90  and optical fiber  92  may be on the order of inches, centimeters, or meters in length. In examples where the components of wireless communications system  95  are located within different devices  10 , central optical controller  90  may be located in the same room or a different room of the same building or a different building as access points  45  or may be located in a different geographic region from access points  45  (e.g., optical fiber  92  may be as long as a few km, dozens of km, hundreds of km, or thousands of km in length). If desired, optical fiber  92  may include multiple optical fibers that are coupled together in series using optical couplers, optical boosters/amplifiers, optical relays, etc. 
     Central optical controller  90  may generate optical local oscillator signals for access points  45 . Central optical controller  90  may transmit the optical local oscillator signals over optical fiber  92 . Optical splitter/combiner  94  may distribute different optical local oscillator signals (e.g., at different frequencies) to access points  45  over optical paths  96 . Access points  45  may transmit wireless signals  32  using the optical local oscillator signals. Each access point  45  may transmit respective THF signals  32  to different respective external devices  98  (e.g., access point  45 - 1  may transmit THF signals  32 - 1  to external device  98 - 1 , access point  45 -M may transmit THF signals  32 -M to external device  98 -M, etc.). The frequencies of THF signals  32  may be given by the difference in wavelength between the optical local oscillator signals provided to each access point  45 . External devices  98  may be other devices such as device  10 , wireless base station or access points, or other wireless (THF) communications equipment, for example. While  FIG.  8    illustrates the transmission of THF signals  32 , wireless communications system  95  may additionally or alternatively receive THF signals  34  ( FIG.  1   ) from external devices  98 . 
     When arranged in this way, wireless communications system  95  performs wavelength-division multiplexing (WDM) to concurrently convey wireless signals using access points  45 . The WDM may be performed both in the optical domain between central optical controller  90  and access points  45  and in the radio-frequency and THF domain within access points  45 . In some implementations, central optical controller  90  includes individual light sources (lasers) that are used to generate optical local oscillator signals at different respective wavelengths for each of the access points  45  in communications system  95 . However, this may undesirably increase the cost of wireless communications system  95 , the size of central optical controller  90 , the power consumption by central optical controller  90 , and the synchronization between channels. To mitigate these issues, central optical controller  90  may generate an optical frequency comb signal that is distributed to access points  45  for use in conveying wireless signals  32  and/or  34 . 
       FIG.  9    is a diagram showing how central optical controller  90  may generate an optical frequency comb signal that is distributed to access points  45  for use in conveying wireless signals  32  and/or  34  (e.g., under a wavelength multiplexing (WDM) scheme where a single LO and multiple bands on fiber are converted to multiple THF bands for serving a single access point or for distribution and splitting across several access points). As shown in  FIG.  9   , central optical controller  90  may include optical receiver  72 , DAC  74 , and signal path  28 . Central optical controller  90  may also include an optical frequency comb signal generator such as frequency comb generator  110  (sometimes referred to herein as optical signal generator  110 ). Frequency comb generator  110  may include LO light sources  70  ( FIG.  6   ) and/or other light emitters that generate an optical frequency comb signal such as frequency comb signal scomb. Frequency comb signal scomb may include an optical LO signal and a comb of optical signals that are offset from the optical LO signal. 
     A comb of optical signals (sometimes referred to as an optical frequency comb or a frequency comb) is a set of evenly-spaced spectral lines (carriers) in the frequency domain at optical frequencies (e.g., where each carrier forms a respective “tooth” of the comb). The optical frequency comb may, for example, include n evenly-spaced carriers, each of which has a respective carrier frequency f n  given by the formula f n =n*f r + f , where f r  is the frequency of the THF signals to be produced by a given access point  45  using that carrier at carrier frequency f n  and f 0  is an offset frequency from 0 Hz (DC). Frequency f r  also corresponds to the difference in frequency between adjacent carriers (e.g., the line spacing of the comb). Frequency f r  may sometimes be referred to herein as comb tooth spacing f r , repetition rate f r , an offset frequency, or a frequency gap. 
     The phases of each of the n carriers in the optical frequency comb may be the same (e.g., all the carriers are phase-locked with respect to each other). In the time domain, the optical frequency comb corresponds to a train of optical pulses and frequency f r  relates to the inverse of the period of the pulse train (e.g., repetition rate). Offset frequency f 0  indicates that the oscillation frequencies of the spectral lines in the optical frequency comb are not necessarily an integer multiple of the repetition rate. Since offset frequency f 0  is most generally independent of frequency f r , there are two degrees of freedom in an optical pulse train that define the absolute position of the lines in the frequency domain. 
     The origin of the offset frequency f 0  may depend on the comb generation architecture implemented in frequency comb generator  110 . Frequency comb generator  110  may include, for example, mode-locked lasers. In these implementations, the origin of the offset frequency f 0  may depend on the relation between the group and phase velocity in the resonating cavity. In implementations where frequency comb generator  110  generates frequency comb signals as modulation spectra around a central frequency f c , the origin of the offset frequency f 0  may depend on the absolute value of the central frequency. For these types of frequency comb signals, frequency f c  may itself form offset frequency f 0  to define the absolute position of the comb. These types of frequency combs may exhibit phase locking between spectral lines. If desired, frequency comb generator  110  may include one or more lasers that emit an optical LO signal and/or one or more other optical signals and one or more resonant cavities that produce the optical frequency comb using the optical LO signal and/or the one or more other optical signals. 
     Plot  114  of  FIG.  9    shows one example of the optical frequency comb in frequency comb signal scomb, in units of power P as a function of frequency F. As shown in plot  114 , frequency comb signal scomb may include a set  122  of n uniformly-spaced carriers (spectral lines)  124 . Set  122  may sometimes also be referred to herein as optical frequency comb  122 . Each carrier  124  may be at a respective carrier frequency and may be separated from one or two adjacent carriers  124  by frequency f r . The first carrier in set  122  is separated from offset frequency f 0  by a fixed amount. Shifting offset frequency f 0  may serve to shift the absolute frequency of each carrier  124 . Carriers  124  may sometimes also be referred to herein as optical carriers  124 , frequency comb carriers  124 , frequency comb components  124 , spectral peaks  124 , lines  124 , or optical tones  124  (e.g., set  122  may form a comb-shaped pattern of optical tones  124  each at a respective carrier frequency and separated from one or two other optical tones  124  in set  122  by the same frequency f r ). Frequency comb generator  110  may also add an optical LO signal at a corresponding local oscillator frequency f LO  to the optical frequency comb in frequency comb signal scomb (e.g., frequency comb signal scomb may include the optical LO signal at LO frequency f LO  and the optical frequency comb shown by set  122  of plot  114 ). 
     As shown in  FIG.  9   , frequency comb generator  110  may generate frequency comb signal scomb and may provide frequency comb signal scomb to signal path  28 . During signal transmission, DAC  74  may provide wireless data DAT to signal path  28 . One or more optical modulators on signal path  28  (e.g., MZM  56  of  FIG.  6   ) may modulate wireless data DAT onto the n carriers  124  in frequency comb signal scomb to produce modulated frequency comb signal scomb′. Signal path  28  may output modulated frequency comb signal scomb′ to optical splitter/combiner  94  over optical path  92 . 
     Plot  118  of  FIG.  9    shows modulated frequency comb signal scomb′ in units of power P as a function of frequency F. As shown in plot  118 , modulated frequency comb signal scomb′ may include optical LO signal  126  at LO frequency f LO . LO frequency f LO  may be offset with respect to offset frequency f 0 . LO signal  126  may be added to frequency comb signal scomb by a separate laser or, if desired, one of the carriers  124  of set  122  may form the optical LO at LO frequency f LO  (e.g., assuming n*f r +f 0 , where n is an integer, meets LO frequency f LO ). 
     The optical modulator(s) in signal path  28  may module wireless data DAT onto M carriers  124  in set  122  of frequency comb signal scomb to produce corresponding modulated carriers  128  in modulated frequency comb signal scomb′. For example, signal path  28  may modulate wireless data onto a first carrier  124  at carrier frequency FA to produce modulated carrier  128 - 1  at carrier frequency FA in modulated frequency comb signal scomb′, may modulate wireless data onto a second carrier  124  at carrier frequency FB to produce modulated carrier  128 - 2  at carrier frequency FB in modulated frequency comb signal scomb′, may modulate wireless data onto a third carrier  124  at carrier frequency FC to produce modulated carrier  128 - 3  at carrier frequency FC in modulated frequency comb signal scomb′, and may modulate wireless data onto a fourth carrier  124  at carrier frequency FD to produce modulated carrier  128 - 4  at carrier frequency FD in modulated frequency comb signal scomb′ (in an example where there are at least M=4 access points  45 ). 
     Each modulated carrier  128  may be separated in frequency from optical LO frequency f LO  by a corresponding THF frequency THFi (e.g., modulated carrier  128 - 1  and carrier frequency FA may be separated from optical LO signal  126  and LO frequency f LO  by THF frequency THF 1 , modulated carrier  128 - 2  and carrier frequency FB may be separated from optical LO signal  126  and LO frequency f LO  by THF frequency THF 2 , modulated carrier  128 - 3  and carrier frequency FC may be separated from optical LO signal  126  and LO frequency f LO  by THF frequency THF 3 , and modulated carrier  128 - 4  and carrier frequency FD may be separated from optical LO signal  126  and LO frequency f LO  by THF frequency THF 4 ). 
     Optical splitter/combiner  94  may receive modulated frequency comb signal scomb′ from signal path  28  over optical path  92 . Optical splitter/combiner  94  may split (demultiplex) modulated frequency comb signal scomb′ into M signal (tone) pairs spair that are provided to respective access points  45  over optical paths  96 . Each signal pair spair may include optical LO signal  126  (e.g., a first optical tone) and a respective one of the modulated carriers  128  from modulated frequency comb signal scomb′ (e.g., a second optical tone). For example, optical splitter/combiner  94  may demultiplex modulated frequency comb signal scomb′ by wavelength/frequency into a first signal pair spair 1  (e.g., having optical LO signal  126  and modulated carrier  128 - 1  at frequency FA, as shown by plot  116 ) that is provided to access point  45 - 1  over optical path  96 - 1 , an Mth signal pair spairM (e.g., having optical LO signal  126  and modulated carrier  128 -M at frequency FM, as shown by plot  120 ) that is provided to access point  45 -M over optical path  96 -M, etc. If desired, each access point  45  may include one or more filters that filter out wavelengths other than the wavelengths of the signal pair spair provided to the access point. 
     The UTC PD(s)  42  in each access point  45  may transmit corresponding THF signals  32  over a respective set of antennas  112  based on the optical LO signal  126  and the corresponding modulated carrier  128  received from optical splitter/combiner  94  (e.g., where optical LO signal  126  forms optical LO signal LO 1  and the modulated carrier  128  forms optical LO signal LO 2  of  FIG.  6   ). The difference in frequency between optical LO signal  126  and the corresponding modulated carrier  128  may determine the frequency of the THF signals  32  transmitted by each access point  45 . For example, access point  45 - 1  may transmit THF signals  32 - 1  at frequency THF 1  and access point  45 -M may transmit THF signals  32 -M at frequency THFM. The set of antennas  112  in each access point  45  may include one or more antenna radiating element arms  36  ( FIG.  6   ) that share a single UTC PD  42  or that are coupled to respective UTC PDs  42  in the access point  45  (e.g., each access point  45  may, if desired, include multiple UTC PDs  42  illuminated by the same signal pair spair). The set of antennas  112  in each access point  45  may, if desired, form a respective phased antenna array or different antennas from different access points may form part of the same phased antenna array. 
     In this way, central optical controller  90  may provide phase-locked optical signals to multiple access points  45  to control the access points to communicate using THF signals with multiple external devices  98  ( FIG.  8   ) at respective THF frequencies (e.g., using a carrier aggregation scheme) while minimizing cost, size, and power consumption, and while ensuring that each of the access points are accurately synchronized with each other. The example of  FIG.  9    in which access points  45  are used to transmit THF signals is merely illustrative. Additionally or alternatively, access points  45  may receive THF signals (e.g., central optical controller  90  need not modulate data onto frequency comb signal scomb). If desired, there may be M=1 access point that includes different sets of antennas  112  that serve several different frequency channels using multiple signal pairs spair. In general, one bandwidth may be distributed to one access point, multiple bandwidths may be distributed to one access point (e.g., all WDMs may be provided to a single access point), multiple bandwidths may be distributed to all access points, etc. If desired, dual-polarization may be performed in addition to WDM and may be applied to both the optical fiber and radio resources of the communications system. 
       FIG.  10    is a flow chart of illustrative operations involved in using multiple access points  45  to transmit wireless signals at frequencies greater than about 100 GHz using an optical frequency comb signal generated by central optical controller  90 . At operation  130 , frequency comb generator  110  on central optical controller  90  may generate frequency comb signal scomb. Frequency comb signal scomb may include an optical frequency comb that includes set  122  of M optical carriers  124  (e.g., as shown by plot  114  of  FIG.  9   ) and optical LO signal  126 . 
     At operation  132 , signal path  28  may generate modulated frequency comb signal scomb′ by modulating data DAT onto each of the carriers  124  in frequency comb signal scomb to produce modulated carriers  128  (e.g., as shown by plot  118  of  FIG.  9   ). 
     At operation  134 , optical path  92 , optical splitter/combiner  94 , and optical paths  96  may distribute modulated optical comb signal scomb′ across the M access points  45 . For example, respective signal pairs spair may be provided to each of the M access points  45 , where each signal pair spair includes optical LO signal  126  and a respective modulated carrier  128 . 
     At operation  136 , each of the M access points  45  may illuminate one or more UTC PDs  42  using its received signal pair spair to transmit wireless signals  32  to a respective external device  98  over one or more antennas  112 . The frequency of wireless signals  32  may be given by the frequency between optical LO signal  126  and the modulated carrier  128  in the signal pair spair used to illuminate the UTC PDs  42 . If desired, the operations of  FIG.  10    may be modified to receive wireless data using access points  45 . 
     If desired, central optical controller  90  may use a single access point  45  to perform multi-user (MU) and/or single-user (SU) multiple input and multiple output (MIMO) communications. In MU MIMO, the access point concurrently conveys multiple data streams with multiple external devices  98  using wireless signals at the same THF frequency. In SU MIMO, the access point concurrently conveys multiple data streams with a single external device  98  using wireless signals at the same THF frequency (e.g., by exploiting the greater than one rank of a transmission system). This often requires rich scattering in the environment, which may be difficult to achieve at THF frequencies. For both MU MIMO and SU MIMO, for a given bandwidth, more data streams need to be provided in optical fiber concurrently. Spatial multiplexing is an option in fiber resources for more than one fiber core but may have substantial cost and deployment drawbacks. If desired, central optical controller  90  may perform SU MIMO and MU MIMO over a single optical fiber such as optical fiber  140  of  FIG.  11   . 
     As shown in  FIG.  11   , communications system  95  may include a single access point  45  coupled to central optical controller  90  over optical fiber  140 . Access point  45  may concurrently transmit M parallel streams of wireless data within THF signals  142  (e.g., THF signals  142 - 1 , THF signals  142 -M, etc.). In an SU MIMO implementation, access point  45  may transmit each stream to a single external device  98 . In an MU MIMO implementation, access point  45  may transmit each stream to a respective one of M different external devices  98  (e.g., external device  98 - 1 , external device  98 -M, etc.). Access point  45  may include one or more UTC PDs  42  coupled to one or more antennas  112 . 
       FIG.  12    is a diagram showing how central optical controller  90  may control access point  45  to transmit concurrent wireless streams under a MU MIMO or SU MIMO arrangement (e.g., for targeting several streams to the same THF frequency). In the example of  FIG.  12   , access point  42  includes M=4 parallel wireless streams for MIMO and four UTC PDs  42  (e.g., UTC PDs  42 - 1 ,  42 - 2 ,  42 - 3  and  42 - 4 ) for producing respective streams of THF signals  142  (e.g., THF signals  142 - 1 ,  142 - 2 ,  142 - 3 , and  142 - 4 , respectively) using corresponding sets of antennas  112  (e.g., antennas  112 - 1  coupled to UTC PD  42 - 1 , antennas  112 - 2  coupled to UTC PD  42 - 2 , antennas  112 - 3  coupled to UTC PD  42 - 3 , and antennas  112 - 4  coupled to UTC PD  42 - 4 ). Depending on the array response, the streams may serve the same spatial direction (e.g., for SU-MIMO with M streams), different spatial directions (e.g., for MU-MIMO with one stream oriented in each direction for spatial distribution to user(s)), or any combination in between. 
     As shown in  FIG.  12   , central optical controller  90  may provide modulated frequency comb signal scomb′ over optical path  140 . When operating under a MU MIMO or SU MIMO scheme, central optical controller  90  may generate modulated frequency comb signal scomb′ with a set of optical LO signals  126  that are each separated from a respective modulated carrier  128  by the same frequency THFX. Each optical LO signal  126  may therefore be separated from one or two adjacent optical LO signals  126  by frequency f r . For example, as shown by plot  141  of  FIG.  12   , modulated frequency comb signal scomb′ may include a first optical LO signal  126 - 1  at a first LO frequency f LO1  separated from modulated carrier  128 - 1  at frequency FA by frequency THFX, may include a second optical LO signal  126 - 2  at a second LO frequency f LO2  separated from modulated carrier  128 - 2  at frequency FB by frequency THFX, may include a third optical LO signal  126 - 3  at a third LO frequency f LO3  separated from modulated carrier  128 - 3  at frequency FC by frequency THFX, and may include a fourth optical LO signal  126 - 4  at a fourth LO frequency f LO4  separated from modulated carrier  128 - 4  at frequency FD by frequency THFX. Frequency comb generator  110  ( FIG.  9   ) may, for example, add each of the optical LO signals at frequencies f LOx  to the spectrum of modulated frequency comb signal scomb′ using a separate laser or using carriers of the optical frequency comb (e.g., carriers  124  in set  122  of  FIG.  9   ). 
     Demultiplexer  150  (e.g., an optical splitter/combiner) may provide a respective signal pair spair from modulated frequency comb signal scomb′ to each of the M UTC PDs  42  in access point  45  over a respective optical path  152 . For example, demultiplexer  150  may provide a first signal pair spair 1  that includes optical LO signal  126 - 1  at frequency f LO1  and that includes modulated carrier  128 - 1  at carrier frequency FA to UTC PD  42 - 1  over optical path  152 - 1  for transmission as THF signals  142 - 1  by antennas  112 - 1 , may provide a second signal pair spair 2  that includes optical LO signal  126 - 2  at frequency f LO2  and that includes modulated carrier  128 - 2  at carrier frequency FB to UTC PD  42 - 2  over optical path  152 - 2  for transmission as THF signals  142 - 2  by antennas  112 - 2 , may provide a third signal pair spair 3  that includes optical LO signal  126 - 3  at frequency f LO3  and that includes modulated carrier  128 - 3  at carrier frequency FC to UTC PD  42 - 3  over optical path  152 - 3  for transmission as THF signals  142 - 3  by antennas  112 - 3 , and may provide a fourth signal pair spair 4  that includes optical LO signal  126 - 4  at frequency f LO4  and that includes modulated carrier  128 - 4  at carrier frequency FD to UTC PD  42 - 4  over optical path  152 - 4  for transmission as THF signals  142 - 4  by antennas  112 - 4 . 
     Access point  45  may include optical filters (e.g., on optical paths  152 ) that filter out the optical local oscillators and modulated carriers other than the signal pair spair intended for each UTC PD  42 . Since each signal pair spair includes a carrier  126  separated from a corresponding modulated carrier  128  by the same frequency THFX, THF signals  142 - 1 ,  142 - 2 ,  142 - 3 , and  142 - 4  may each be transmitted at the same frequency THFX, for example. If there are multiple external devices  98  that are spatially separated, antennas  112 - 1 ,  112 - 2 ,  112 - 3 , and  112 - 4  may transmit THF signals  142 - 1 ,  142 - 2 ,  142 - 3 , and  142 - 4  in different respective directions (e.g., using beam forming). Dual polarization may also be added to the MIMO streams both in the optical fiber and in radio resources. The example of  FIG.  12    in which access point  45  is used to transmit THF signals is merely illustrative. Additionally or alternatively, access point  45  may receive THF signals (e.g., central optical controller  90  need not modulate data onto frequency comb signal scomb). The example of  FIG.  12    in which a single access point is used is merely illustrative. In general, there may be (e.g., for the same THF frequency) two streams provided to a first access point and two streams provided to a second access point or any combination of number of streams provided to any number of access points. 
       FIG.  13    is a flow chart of illustrative operations involved in using a single access point  45  to transmit wireless signals at frequencies greater than about 100 GHz using multiple concurrent wireless streams (e.g., under an SU MIMO or MU MIMO scheme). 
     At operation  160 , frequency comb generator  110  on central optical controller  90  may generate frequency comb signal scomb. Frequency comb generator  110  may include an optical frequency comb (e.g., set  122  of optical carriers  124  of  FIG.  9   ) in frequency comb signal scomb. Frequency comb generator  110  may also include a set of optical LO signals  126  in frequency comb signal scomb. The set of optical LO signals  126  may include the same number of optical LO signals as there are carriers in the optical frequency comb. Each of the optical LO signals may be separated from one or two adjacent optical LO signals by the same frequency spacing (e.g., frequency f r ) as between the carriers  124  in the optical frequency comb. In this way, each optical LO signal may be separated from a respective carrier  124  in the optical frequency comb by the same frequency THFX ( FIG.  12   ). 
     At operation  162 , signal path  28  on central optical controller  90  may generate modulated frequency comb signal scomb′ by modulating data (e.g., different data streams for concurrent transmission to the same external device  98  under an SU MIMO scheme or for concurrent transmission to multiple external devices  98  under an MU MIMO scheme) onto the carriers  124  in the optical frequency comb of frequency comb signal scomb. 
     At operation  164 , central optical controller  90  may provide modulated frequency comb signal scomb′ to access point  45  over optical path  140  ( FIG.  12   ). 
     At operation  166 , demultiplexer  150  (e.g., at access point  45 ) may demultiplex modulated frequency comb signal scomb′ to provide a respective signal pair spair to each of the UTC PDs  42  in access point  45  over corresponding optical paths  152 . Each signal pair spair may include a respective optical local oscillator signal  126  and a corresponding modulated carrier signal  128 - 1  separated from the optical local oscillator signal  126  by frequency THFX. 
     At operation  168 , each UTC PD  42  in access point  45  may be illuminated by the respective signal pair spair provided by demultiplexer  150 . This may cause each UTC PD  42  to transmit respective THF signals  142  at frequency THFX using the corresponding antennas  112 . Each UTC PD  42  may transmit the THF signals concurrently to the same external device  98  or to multiple external devices  98 . If desired, the operations of  FIG.  10    may be modified to receive wireless data using access points  45 . The operations of  FIGS.  10  and  13    may be combined (e.g., central optical controller  90  may provide modulated frequency comb signals scomb′ that perform both carrier aggregation and MIMO schemes. The optical components described herein (e.g., MZM modulator(s), waveguide(s), phase shifter(s), UTC PD(s), etc.) may be implemented in plasmonics technology if desired. 
     Device  10  may gather and/or use personally identifiable information. It is well understood that the use of personally identifiable information should follow privacy policies and practices that are generally recognized as meeting or exceeding industry or governmental requirements for maintaining the privacy of users. In particular, personally identifiable information data should be managed and handled so as to minimize risks of unintentional or unauthorized access or use, and the nature of authorized use should be clearly indicated to users. 
     The methods and operations described above in connection with  FIGS.  1 - 13    (e.g., the operations of  FIGS.  10  and  13   ) may be performed by the components of device  10  using software, firmware, and/or hardware (e.g., dedicated circuitry or hardware). Software code for performing these operations may be stored on non-transitory computer readable storage media (e.g., tangible computer readable storage media) stored on one or more of the components of device  10  (e.g., storage circuitry  16  of  FIG.  1   ). The software code may sometimes be referred to as software, data, instructions, program instructions, or code. The non-transitory computer readable storage media may include drives, non-volatile memory such as non-volatile random-access memory (NVRAM), removable flash drives or other removable media, other types of random-access memory, etc. Software stored on the non-transitory computer readable storage media may be executed by processing circuitry on one or more of the components of device  10  (e.g., processing circuitry  18  of  FIG.  1   , etc.). The processing circuitry may include microprocessors, central processing units (CPUs), application-specific integrated circuits with processing circuitry, or other processing circuitry. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20220822
Publication Date: 20240402
Grant Date: 20240402
Priority Date: 20210921
Inventors: GUNZELMANN, Bertram R
BOOS, ZDRAVKO
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B10/6164", "inventive": true, "first": true, "tree": "[]"}, {"code": "G02B6/2938", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B10/25759", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B10/63", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B10/25758", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B10/6164", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04H20/71", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B2210/006", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04B10/25759", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B10/63", "inventive": true, "first": false, "tree": "[]"}, {"code": "G02B6/2938", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 85571829