Patent Description:
Conventional approaches for active optical alignment may be costly, cumbersome, and/or inefficient-e.g., they may be complex and/or time consuming, and/or may introduce asymmetry.

In <CIT>, a photonic integrated circuit (PIC) may be optically aligned to a plurality of optical components (e.g., an optical fiber array). Optical alignment may be facilitated by the use of an optical impedance element coupled between a first input/output (I/O) optical waveguide and a second I/O optical waveguide of the PIC. The optical impedance element me be configured to be transmissive during optical alignment and to be non-transmissive during the regular operation of the PIC.

In <CIT>, a wafer test system includes an input device configured to transmit a test signal, a wafer including an optical port, an input port configured to receive the test signal, and an output port configured to output a result signal based on the test signal, a measuring device configured to measure the result signal, and an alignment device configured to align an optical fiber port of an optical probe with an alignment port based on the result signal and then align the optical fiber port with the optical port. The alignment port is the input port or the output port. The optical probe is configured to be the input device when the input port is the alignment port and the optical probe is configured to be the measuring device when the output port is the alignment port.

Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present disclosure as set forth in the remainder of the present application with reference to the drawings.

System and methods are provided for optical alignment to a silicon photonically-enabled integrated circuit, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the present disclosure, as well as details of an illustrated embodiment thereof, will be more fully understood from the following description and drawings.

As utilized herein, circuitry or a device is "operable" to perform a function whenever the circuitry or device comprises the necessary hardware and code (if any is necessary) to perform the function, regardless of whether performance of the function is disabled or not enabled (e.g., by a user-configurable setting, factory trim, etc.).

<FIG> is a block diagram of a photonically-enabled integrated circuit with built-in optical alignment, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there is shown optoelectronic devices on a photonically-enabled integrated circuit <NUM> comprising optical modulators 105A-105D, photodiodes 111A-111D, monitor photodiodes 113A-<NUM>, and optical devices comprising couplers 103A-<NUM>, optical terminations 115A-115D, and grating couplers 117A-<NUM>. There are also shown electrical devices and circuits comprising amplifiers 107A-107D, analog and digital control circuits <NUM>, and control sections 112A-112D. The amplifiers 107A-107D may comprise transimpedance and limiting amplifiers (TIA/LAs), for example.

In an example scenario, the photonically-enabled integrated circuit <NUM> comprises a CMOS photonics die with a laser assembly <NUM> coupled to the top surface of the IC <NUM>. The laser assembly <NUM> may comprise one or more semiconductor lasers with isolators, lenses, and/or rotators for directing one or more CW optical signals to the coupler 103A. The photonically enabled integrated circuit <NUM> may comprise a single chip, or may be integrated on a plurality of die, such as one or more electronics die and one or more photonics die.

Optical signals are communicated between optical and optoelectronic devices via optical waveguides <NUM> fabricated in the photonically-enabled integrated circuit <NUM>. Single-mode or multi-mode waveguides may be used in photonic integrated circuits. Single-mode operation enables direct connection to optical signal processing and networking elements. The term "single-mode" may be used for waveguides that support a single mode for each of the two polarizations, transverse-electric (TE) and transverse-magnetic (TM), or for waveguides that are truly single mode and only support one mode whose polarization is TE, which comprises an electric field parallel to the substrate supporting the waveguides. Two typical waveguide cross-sections that are utilized comprise strip waveguides and rib waveguides. Strip waveguides typically comprise a rectangular cross-section, whereas rib waveguides comprise a rib section on top of a waveguide slab. Of course, other waveguide cross section types are also contemplated and within the scope of the disclosure.

In an example scenario, the couplers 103A-103C may comprise low-loss Y-junction power splitters where coupler 103A receives an optical signal from the laser assembly <NUM> and splits the signal to two branches that direct the optical signals to the couplers 103B and 103C, which split the optical signal once more, resulting in four roughly equal power optical signals.

The optical power splitter may comprise at least one input waveguide and at least two output waveguides. The couplers 103A-103C shown in <FIG> illustrates <NUM>-by-<NUM> splitters, which divide the optical power in one waveguide into two other waveguides evenly. These Y-junction splitters may be used in multiple locations in an optoelectronic system, such as in a Mach-Zehnder interferometer (MZI) modulator, e.g., the optical modulators 105A-105D, where a splitter and a combiner are needed, since a power combiner can be a splitter used in reverse.

In another example scenario, the Y-junction may be utilized in a parallel multichannel transmitter, where a cascade of <NUM>-by-<NUM> splitters can be employed to have a single light source feed multiple channels. Interleaver-based multiplexers and demultiplexers constitute a third example where <NUM>-by-<NUM> splitters are among the building blocks.

The optical modulators 105A-105D comprise Mach-Zehnder or ring modulators, for example, and enable the modulation of the continuous-wave (CW) laser input signal. The optical modulators 105A-105D may comprise high-speed and low-speed phase modulation sections and are controlled by the control sections 112A-112D. The high-speed phase modulation section of the optical modulators 105A-105D may modulate a CW light source signal with a data signal. The low-speed phase modulation section of the optical modulators 105A-105D may compensate for slowly varying phase factors such as those induced by mismatch between the waveguides, waveguide temperature, or waveguide stress and is referred to as the passive phase, or the passive biasing of the MZI.

In an example scenario, the high-speed optical phase modulators may operate based on the free carrier dispersion effect and may demonstrate a high overlap between the free carrier modulation region and the optical mode. High-speed phase modulation of an optical mode propagating in a waveguide is the building block of several types of signal encoding used for high data rate optical communications. Speed in the several Gb/s may be required to sustain the high data rates used in modern optical links and can be achieved in integrated Si photonics by modulating the depletion region of a PN junction placed across the waveguide carrying the optical beam. In order to increase the modulation efficiency and minimize the loss, the overlap between the optical mode and the depletion region of the PN junction is optimized.

The outputs of the optical modulators 105A-105D may be optically coupled via the waveguides <NUM> to the grating couplers 117E-<NUM>. The couplers 103D-<NUM> may comprise four-port optical couplers, for example, and may be utilized to sample or split the optical signals generated by the optical modulators 105A-105D, with the sampled signals being measured by the monitor photodiodes 113A-<NUM>. The unused branches of the directional couplers 103D-<NUM> may be terminated by optical terminations 115A-115D to avoid back reflections of unwanted signals.

The grating couplers 117A-<NUM> comprise optical gratings that enable coupling of light into and out of the photonically-enabled integrated circuit <NUM>. The grating couplers 117A-117D may be utilized to couple light received from optical fibers into the photonically-enabled integrated circuit <NUM>, and the grating couplers 117E-<NUM> may be utilized to couple light from the photonically-enabled integrated circuit <NUM> into optical fibers. The grating couplers 117A-<NUM> may comprise single polarization grating couplers (SPGC) and/or polarization splitting grating couplers (PSGC). In instances where a PSGC is utilized, two input, or output, waveguides may be utilized.

The optical fibers may be affixed using epoxy, for example, to the CMOS chip, and may be aligned at an angle from normal to the surface of the photonically-enabled integrated circuit <NUM> to optimize coupling efficiency. In an example embodiment, the optical fibers may comprise single-mode fiber (SMF) and/or polarization-maintaining fiber (PMF).

The photodiodes 111A-111D may convert optical signals received from the grating couplers 117A-117D into electrical signals that are communicated to the amplifiers 107A-107D for processing. In another embodiment of the disclosure, the photodiodes 111A-111D may comprise high-speed heterojunction phototransistors, for example, and may comprise germanium (Ge) in the collector and base regions for absorption in the <NUM>-<NUM> optical wavelength range, and may be integrated on a CMOS silicon-on-insulator (SOI) wafer.

In the receiver subsystem implemented in a silicon chip, light is often coupled into a photodetector via a polarization-splitting grating coupler that supports coupling all polarization states of the fiber mode efficiently. The incoming signal is split by the PSGC into two separate waveguides in a polarization-diversity scheme, and therefore both inputs to the waveguide photodetectors are used. If two different PSGCs are required to couple into the same photodetector, then the PD has have four separate waveguide ports.

The analog and digital control circuits <NUM> may control gain levels or other parameters in the operation of the amplifiers 107A-107D, which may then communicate electrical signals off the photonically-enabled integrated circuit <NUM>. The control sections 112A-112D comprise electronic circuitry that enable modulation of the CW laser signal received from the splitters 103A-103C. The optical modulators 105A-105D may require high-speed electrical signals to modulate the refractive index in respective branches of a Mach-Zehnder interferometer (MZI), for example.

In operation, the photonically-enabled integrated circuit <NUM> may be operable to transmit and/or receive and process optical signals. Optical signals may be received from optical fibers by the grating couplers 117A-117D and converted to electrical signals by the photodetectors 111A-111D. The electrical signals may be amplified by transimpedance amplifiers in the amplifiers 107A-107D, for example, and subsequently communicated to other electronic circuitry, not shown, in the photonically-enabled integrated circuit <NUM>.

Integrated photonics platforms allow the full functionality of an optical transceiver to be integrated on a single chip. An optical transceiver chip contains optoelectronic circuits that create and process the optical/electrical signals on the transmitter (Tx) and the receiver (Rx) sides, as well as optical interfaces that couple the optical signals to and from a fiber. The signal processing functionality may include modulating the optical carrier, detecting the optical signal, splitting or combining data streams, and multiplexing or demultiplexing data on carriers with different wavelengths, and equalizing signals for reducing and/or eliminating inter-symbol interference (ISI), which may be a common impairment in optical communication systems.

In the field of fiber optic communications, the packaging of optical components has long been recognized as costly and problematic and often this limits the applications of photonic solutions. This problem is more difficult when the components to be aligned are being used to construct a single mode transmission system. In such single mode systems, the requirements for low loss coupling necessitate alignments to approximately <NUM> micron or less. Performing such alignment by purely passive means (i.e. using visual/mechanical alignment) is often not possible unless submicron mechanical alignment features can be incorporated into the parts being aligned.

In practice, it is difficult to incorporate mechanical alignment features and only a small number of problems can be solved with such an approach. More often, one must resort to so called "active alignment" processes where the components to be aligned must be activated (i.e. powered on) and are aligned with the aid of a feedback signal. Typically, these critical active alignments must be done at an advanced stage of the assembly process where the system or portions of the system can be made active to facilitate the generation of a suitable feedback signal for alignment. In this case, because the alignment process is using functional blocks specific to a particular product's function, the alignment process and tooling must be tailored specifically for that product. As such, each new product, even when the same underlying technology is used, often requires new tooling and processes requiring both the tool and the process to be tailored on a product-by-product basis.

In an example embodiment of the disclosure, passive optical taps with feedback loops to grating couplers for transmission back out of the chip may be utilized in the photonically-enabled integrated circuit <NUM> to enable active alignment to the photonically enabled integrated circuits. The disclosure allows the construction of a passive (i.e. not requiring power or control of silicon photonically-enabled integrated circuit), product-independent, and design-rule driven platform for scalable and cost effective active optical alignment to silicon photonically-enabled integrated circuits. The method and system can be used for both packaging and test of components constructed from silicon photonically enabled integrated circuits. In addition, accurate monitoring of the alignment stability of temperature sensitive light sources through the attach process using a normalization detector is disclosed.

Silicon photonically-enabled integrated circuit technology allows for the ubiquitous use of optical library components that can be integrated compactly, with essentially no additional cost, into large scale electro-optical circuits. The disclosure describes using passive optical sub-circuits connected to the photonic input/output nodes of a silicon photonic die, combined together with optically enabled tooling, to create optical feedback signal for active optical alignment of input/output components. The disclosed system and method do not rely on the inward or outward coupling path for any particular product, but rather follows product-independent design rules, which allows a more general solution to the technological problem of active optical alignment that is made practical by the ability to freely add passive optical components such as splitters and surface grating couplers to photonic integrated circuits.

<FIG> is a diagram illustrating an exemplary photonically-enabled integrated circuit, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there is shown the photonically-enabled integrated circuit <NUM> comprising electronic devices/circuits <NUM>, optical and optoelectronic devices <NUM>, a light source interface <NUM>, a chip front surface <NUM>, an optical fiber interface <NUM>, CMOS guard ring <NUM>, and a surface-illuminated monitor photodiode <NUM>.

The light source interface <NUM> and the optical fiber interface <NUM> comprise grating couplers, for example, that enable coupling of light signals via the CMOS chip surface <NUM>, as opposed to the edges of the chip as with conventional edge-emitting/receiving devices. Coupling light signals via the chip surface <NUM> enables the use of the CMOS guard ring <NUM> which protects the chip mechanically and prevents the entry of contaminants via the chip edge.

The electronic devices/circuits <NUM> comprise circuitry such as the amplifiers 107A-107D and the analog and digital control circuits <NUM> described with respect to <FIG>, for example. The optical and optoelectronic devices <NUM> comprise devices such as the couplers 103A-<NUM>, optical terminations 115A-115D, grating couplers 117A-<NUM>, optical modulators 105A-105D, high-speed heterojunction photodiodes 111A-111D, and monitor photodiodes 113A-113I.

<FIG> is a diagram illustrating a photonically-enabled integrated circuit coupled to an optical fiber cable, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there is shown the photonically-enabled integrated circuit <NUM> comprising the chip surface <NUM> and the CMOS guard ring <NUM>. There are also shown a fiber-to-chip coupler <NUM>, an optical fiber cable <NUM>, and an optical source assembly <NUM>.

The photonically-enabled integrated circuit <NUM> comprises the electronic devices/circuits <NUM>, the optical and optoelectronic devices <NUM>, the light source interface <NUM>, the chip surface <NUM>, and the CMOS guard ring <NUM> may be as described with respect to <FIG> for example.

In an example embodiment, the optical fiber cable may be affixed, via epoxy for example, to the CMOS chip surface <NUM>. The fiber chip coupler <NUM> enables the physical coupling of the optical fiber cable <NUM> to the photonically-enabled integrated circuit <NUM>. In another example scenario, the IC <NUM> may comprise photonic devices on one die, such as a photonics interposer, and electrical devices on an electronics die, both of which may comprise CMOS die.

The coupling of the fiber-to-chip coupler <NUM> and the optical source assembly <NUM> may be enabled with a gripper in a pick-and-place tool that comprises one or more optical fibers that coupled to couplers in the optical chip <NUM> such that the optical circuitry and/or the optical sources may be tested in an active alignment procedure, while not requiring the powering up of the chip <NUM>. This "pseudo-active" alignment follows product-independent design rules, which allows a more general solution to the technological problem of active optical alignment that is made practical by the ability to freely add passive optical components such as splitters and surface grating couplers to photonic integrated circuits.

While a single die is shown in <FIG>, the chip <NUM> may instead comprise a plurality of die. In an example scenario, one or more electronic die may be coupled to a photonics die, i.e., a photonic interposer, comprising optical and optoelectronic devices for communicating optical signals between electronics die, for example.

<FIG> illustrates a micro-packaged laser light source to be aligned to an photonic integrated circuit, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there are shown a component <NUM>, a gripper <NUM>, an optical fiber <NUM>, and a photonic integrated circuit <NUM> with grating coupler 209A and 209B. The component <NUM> may comprise a micro-packaged light source that may be configured to direct an output beam through the bottom of the package at an angle that is designed to couple into the grating coupler 209A on the surface of the photonic integrated circuit <NUM>. The optical fiber <NUM> may comprise a multi-mode fiber for receiving optical signals from the photonic IC <NUM> even in instances when not perfectly aligned with output grating couplers.

The gripper <NUM> comprises an automated pick and place tool, for example, that may place components on integrated circuits. The gripper may use mechanical and/or vacuum techniques to hold packages for placement. The gripper <NUM> comprises one or more optical fibers, such as optical fiber <NUM>, for receiving optical signals from the die <NUM>, enabling the active alignment of devices without powering up full functionality of the die <NUM>. The gripper <NUM> may be moved in multiple directions to maximize the optical signals, thereby aligning the component <NUM> to the die <NUM>.

Passive taps may be incorporated into the photonic integrated circuit <NUM> to direct a small portion of the coupled light to an output grating coupler 209B that is positioned according to a fixed design rule, which is based on the component and tooling, to couple that small portion of light into a large diameter multi-mode fiber <NUM> that has been incorporated into the gripper <NUM> that holds the micro-packaged light source. The inclusion of the feedback collection element, the multi-mode fiber in this example, into the gripper further makes this technique agnostic to the actual product design or form-factor that the light source is being attached to. As an example of the utility of this approach, the same tooling and integrated circuit design may be used to align micro-packaged light sources of different size/output-power.

<FIG> illustrates the alignment of a fiber array to a photonic integrated circuit with multiple feedback paths to enable simultaneous alignment of multiple fibers and grating input/output couplers, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there are shown a component <NUM>, a gripper <NUM>, multi-mode fibers <NUM>, a photonic die <NUM>, and a fiber array <NUM>. The gripper <NUM> comprises an automated pick and place tool, for example, that may place components on integrated circuits. The gripper <NUM> may use mechanical and/or vacuum techniques to hold packages for placement. The gripper <NUM> comprises one or more optical fibers, such as optical fibers <NUM>, for coupling optical signals into and receiving optical signals from the die <NUM>, enabling the active alignment of devices without powering up full functionality of the die <NUM>. The component <NUM> may comprise an integrated circuit die or an optical source assembly coupled to the photonic die <NUM>, where as an optical source assembly, the component <NUM> is operable to provide optical source signals for the photonic die <NUM>.

The photonic die <NUM> may comprise optical, optoelectronic, and electronic devices, such as those described with respect to <FIG> for example. The fiber array <NUM> may comprise an array of single-mode fibers, for example, for coupling optical signals into and out of the photonic die <NUM>. In an example embodiment, the fiber array <NUM> comprises <NUM> or <NUM> fibers that communicate optical signals to and from grating couplers in the photonic die <NUM>.

In this example, the fiber gripper <NUM> incorporates two multi-mode fibers that lead to two separate detectors. The optical fibers <NUM> may comprise multi-mode fibers that are large enough in diameter to collect optical signals when not exactly aligned with an output grating coupler in the photonic die <NUM>, enabling proper alignment by maximizing the received optical signal. The gripper <NUM> may be moved in multiple directions to maximize the optical signals, thereby aligning the fiber array <NUM> to the photonic die <NUM>.

This coupling of optical signals into the multi-mode fibers <NUM> allows the yaw and position of the fiber array to be configured for optimum coupling and ensures the correct alignment of the fiber array <NUM> to the die <NUM>. This structure also allows the same tooling to be used on arrays of different size and fiber count provided the distance from the gripped edge of the array to the outermost fiber is kept as a design constant. This approach enables the same tooling to be used to grip and align both <NUM> fiber channel arrays and <NUM> fiber channel arrays, for example.

<FIG> illustrates a partial photonic routing schematic for a passive tap circuit that enables alignment of a micro-packaged light source without enabling/powering the photonic integrated circuit, in accordance with an example embodiment of the disclosure. Referring to <FIG>, there are shown grating couplers 401A and 401B, a mode filter <NUM>, and taps 405A and 405B. The mode filter <NUM> comprises an optical filter for filtering out any extraneous modes, such as cladding modes for example, that are coupled into the grating coupler 401A.

The grating couplers 401A and 401B may comprise single polarization grating couplers, for example, for coupling optical signals into and/or out of the photonic circuit <NUM>. The distance between the grating couplers 401A and 401B may be a product-independent distance, xalign for example, that may be used for the grippers or other similar tooling that place devices, which can then be used for any photonics die.

The taps 405A and 405B may comprise stabilized directional couplers for splitting a portion of a received optical signal into first and second output paths. The amount coupled to each output may be configured by the thickness of and spacing between waveguides in the couplers. Accordingly, a small portion may be split into the alignment photonic circuitry with the majority of the signal being coupled to the main transceiver circuitry, as described with respect to <FIG> for example.

The photonic circuit <NUM> is an example of the photonic schematic used to implement a passive alignment tap as shown in <FIG>. As described, larger diameter multi-mode fibers may be utilized to guide the alignment light to a detector used to generate the feedback signal. In principle, it is also possible to directly illuminate a large (>><NUM> micron) detector via grating couplers in the die. In this example, the use of large diameter multi-mode fiber allows greater latitude in the design of the gripper tooling. In an example scenario, the feedback detector has a receiving aperture that is large when compared to the spatial overlap of the component/grating coupler to be aligned.

In operation, when an optical source is being coupled to the die, it may be placed over the grating coupler 401A, such that an optical signal is coupled into the photonic circuit <NUM> and to the filter <NUM>, which filters out optical signals other than the desired mode, which is then coupled to the tap 405A. One output of the tap 405A is the input signal to a splitter network, such as the couplers 103A-103C described with respect to <FIG>, for example, while the other output is coupled to the second tap 405B. A first output of the tap 405B is coupled to a monitor photodiode that is used to monitor the laser source during normal operation while a second output of the tap 305B is coupled to the grating coupler 401B, which couples the signal vertically out of the die where it may be captured by a multi-mode fiber, such as the fiber <NUM>, described with respect to <FIG> for example. This optical signal may be coupled to a detector, as described with to respect to <FIG> for example, for monitoring the alignment process. Maximizing the optical signal received at the photodetector indicates an optimum optical alignment of the laser input signal.

<FIG> shows an example of a partial photonic routing schematic for a passive tap circuit designed to enable alignment of a fiber array without enabling/powering the photonic integrated circuit, in accordance with an example embodiment of the disclosure. The photonic circuit <NUM> comprises arrays of grating couplers 501A-501V for the fiber array to be coupled to the photonic circuit <NUM> as well as for the alignment fibers. There is also shown an optical assembly <NUM> and taps 505A-505F. In an example embodiment, the grating couplers 501A-501E and 501J-<NUM> comprise single polarization grating couplers while grating couplers 501F-<NUM> and 501N-501V comprise polarization splitting grating couplers.

The optical assembly <NUM>, as indicated by the dashed line, may comprise an array of optical fibers, for example, similar to the fiber-to-chip coupler <NUM> with fibers <NUM> or fiber array <NUM> described above. As shown in <FIG>, optical signals may be coupled from the optical assembly <NUM> into grating couplers 510B-501Q on the photonic chip, routed via optical waveguides on the photonic chip to a tap, such as the taps 505A-505E, where a portion of the signal may be fed back to the alignment structure via another large diameter fiber. The remaining signal may be coupled into Rx and/or Tx optical circuitry for testing. The distance between the grating couplers, xalign, for the large diameter fibers may be dictated by the design of the gripper that places the optical assembly.

The grating couplers <NUM>-501V may comprise optional extra alignment couplers, where these PSGCs are offset from the main axis of the optical assembly <NUM> for further alignment capability. In addition, polarization alignment capability is thereby provided in instances when the input signal polarization is not aligned properly when the input signal is coupled to the single polarization grating coupler 501B, as the grating coupler <NUM> will couple different polarizations.

<FIG> shows a variation of an optically-enabled gripper with photodetectors, in accordance with an example embodiment of the disclosure. The gripper assembly <NUM> comprises a photodetector <NUM>, a large area detector <NUM>, gripper arms <NUM>, a light source assembly <NUM> for mounting to a die, and a fiber <NUM>. The photodetector <NUM> may comprise a TO-can type detector mounted in the gripper assembly <NUM> for sensing optical signals from fiber <NUM>. The light source assembly may comprise one or more lasers for providing optical signals to a die to which it is affixed, and may be similar to the optical source assembly <NUM> described above for example.

The large area detector <NUM> may be operable to collect scattered light from the alignment environment that can be used to normalize the coupled light signal. The signal on the large area normalization detector <NUM> may be proportional to the lasing power and can be used to normalize the coupled power signal even though the temperature may fluctuate during the process. This monitoring of scattered light using the large area detector <NUM> is a particularly useful tool to help accurately monitor the coupling efficiency of a temperature sensitive light source (i.e. where output power fluctuates with temperature), because the fixing process with heat or ultraviolet light heats the light source assembly and decreases its emission power such that it would be impractical in a production process to wait for the whole assembly to cool to the precure temperature to make an accurate measurement of the pre-to-post cure coupling change. With the aid of the normalization large area detector <NUM>, the change in the coupling efficiency can be assessed accurately without waiting for the light source temperature to stabilize.

Claim 1:
A method for optical alignment, the method comprising:
aligning an optical assembly (<NUM>) to a photonics die (<NUM>, <NUM>) comprising a transceiver without powering the photonics die (<NUM>, <NUM>) by, at least:
placing the optical assembly (<NUM>) on the photonics die (<NUM>, <NUM>) using a gripper (<NUM>, <NUM>, <NUM>) having an optical fiber (<NUM>, <NUM>, <NUM>);
communicating one or more optical signals from said optical assembly (<NUM>) into a plurality of grating couplers (<NUM>, <NUM>, <NUM>) in said photonics die (<NUM>, <NUM>);
communicating said one or more optical signals from said plurality of grating couplers (<NUM>, <NUM>, <NUM>) to optical taps (405A, 505A), each tap having a first output coupled to said transceiver and a second output coupled to a corresponding output grating coupler; and
monitoring, using a photodetector (<NUM>) in the gripper (<NUM>, <NUM>, <NUM>), an output optical signal communicated out of said photonics die (<NUM>, <NUM>) via said output grating couplers and to said photodetector (<NUM>) via said optical fiber (<NUM>, <NUM>, <NUM>).