Patent ID: 12253716

DETAILED DESCRIPTION

In many embodiments, the current disclosure may enable the design, creation, and/or implementation of a photonic circuit having the flexibility to function with different configurations of lasers to power multiple parallel channels or lanes of externally modulated transmitters. In various embodiments herein, channel and lane may be used interchangeably. In most embodiments, laser(s) may provide optical energy to an optical transmitter to create multiple output channels. In various embodiments, the optical energy may satisfy the power demands of a given link and compensate for optical losses such as from coupling, splitting, modulating, and routing light.

For example, in one embodiment, transmitters with four parallel channels can use four lasers (one for each channel), or share two lasers among the four channels, or share one laser among the four channels. In these embodiments, each channel may be able to provide one of a plurality of signaling levels within each channel. For example, in some embodiments, a 400G Ethernet connection may be converted at an optical interconnect using a DR4 PAM4 standard. In these embodiments, DR4 may mean there are four parallel channels while PAM4 may mean that within each channel it is using 4-levels of pulse amplitude modulation.

In various embodiments, it may be preferable to use as few lasers as possible, which may reduce a cost of the components and complexity of assembly. In other embodiments, the higher output power requirement when sharing the laser(s) may need to have a different tradeoff in laser price and/or electrical power consumption. In most embodiments, different laser input configurations may be adopted depending on various factors including system requirements, component performances, power, cost, etc.

Generally, each implementation of a photonic circuit transmitter (i.e., an optical engine without the laser(s)) is optimized for a specific laser input configuration (i.e., number of laser(s) to use). As a result, when one wants to change between for example using one laser or using two lasers for a 4-channel transmitter, typically a different photonic circuit is required, which adds to the development cost.

In various embodiments, the current disclosure may enable creation and/or design of an optical network, on a photonic circuit, in such a way that the photonic circuit has the desired number of output parallel ports and multiple input ports, where one may be able to use a subset of these input ports to enable different laser input configurations with the same photonic circuit. In most embodiments, an optical splitter may be named for its respective functions and purpose (e.g., a 1×2 splitter splits one signal into two lanes or channels; a 1×4 splitter splits one signal into 4 lanes or channels). In these example embodiments, each lane may be a parallel optical channel, and each channel may be connected to an optical modulator and an output port. In these embodiments, the splitters may have fixed and even splitting ratios, but can be made adjustable or non-even as well.

In various embodiments, a lane or channel may be an optical fiber, optical path, waveguide, and/or other equivalent medium. In certain embodiments, a splitter may not require each and every input port to be used. For example, in some embodiments, a 2×2 splitter may provide two lanes or channels while using one of the two input ports, while the other input port remains unused, functionally similar as a 1×2 splitter. In various embodiments, splitters may be passive splitters. In some embodiments, one or more splitters used within a photonic circuit may be an active splitter with one or more control elements to adjust the splitting ratio. In certain embodiments, various optical signal distributors/devices and/or components may include optical splitters, active optical splitters, passive optical splitters, optical couplers, optical multiplexers, and/or optical circulators.

In many embodiments, the disclosed network of splitters on a photonic circuit may include multiple tiers, layers, or levels of splitters. In some embodiments, the network may include various numbers of 1×2 splitters and 2×2 splitters. In other embodiments, the network may include other splitters such as 1×3, 1×4, 2×4 splitters, etc. In various embodiments, the output ports of the network may be the desired number of parallel channels, connected to optical paths such as modulators. In some embodiments, the input ports of the network may be selected and connected to laser(s). In various embodiments, some of the input ports may bypass certain levels of the splitters.

Refer now to the example embodiment ofFIG.1, which shows an example system, in accordance with one or more aspects of the disclosure. As shown, the system100includes optical interconnect105-A and optical interconnect105-B in communication using a fiber optic cable140. As shown, each of the optical interconnects (105-A,105-B,105generally) includes a photonic circuit and one or more lasers. A photonic circuit includes an optical network configured to receive optical signals from one or more of the lasers to provide an optical output signal that is sent across the fiber optic cable140. In this embodiment, the signals sent across the fiber optic cable140are used to communicate between optical interconnect105-A and optical interconnect105-B. In various embodiments, system requirements, component performance levels, power, cost, and/or other factors may dictate how many lasers are used in each implementation.

Refer now to the example embodiments ofFIGS.2A and2Bwhich shows a four parallel channels and a splitter network enabling the choice of using one laser or using two lasers with the same photonic integrated circuit (PIC), in accordance with one or more aspects of the disclosure. As shown, an optical network interconnect200includes a photonic circuit210. The photonic circuit210is capable of creating four channels. In the embodiments ofFIGS.2A and2B, the photonic circuit210includes an optical network comprising a single 1×2 splitter215, two 2×2 splitters (220A/220B,220generally), and optionally, it may also include optical modulators (225A . . . D,225generally). Photonic circuit210is enabled to receive optical signals from laser(s) via input port(s) (230-A . . . C,230generally). Input port230-A is connected to 2×2 splitter220A, input port230-B is connected to 1×2 splitter215, and input port230-C is connected to 2×2 splitter220-B. 1×2 splitter215has output235-A, which connects to 2×2 splitter220-A, and output235-B, which connects to 2×2 splitter220-B. 2×2 splitter220A includes output ports240-A and241-B, which connect to optical modulators225-A and225-B respectively.

Similarly, 2×2 splitter220-B includes output ports240-C and240-D, which connect to optical modulators225-C and225-D respectively. Each of the optical modulators225output a modulated optical signal via channels (245-A . . . D,245generally). In most embodiments, the various connections can be implemented using waveguides. InFIGS.2A and2B, the line segments shown connecting optical elements define one or more optical paths between the various components. In this embodiment, as shown in bothFIGS.2A and2B, the combination of splitters215,220and channels235creates a y-shaped topology within the PIC.

FIG.2Ashows photonic circuit210in a first configuration where two lasers (laser205-A and laser205-C) are used to power the four channels245. Specifically, laser205-A provides a light source to photonic circuit210via input channel230-A and laser205-C provides a light source to photonic circuit210via input channel230-C. In this configuration, input ports230-B and optical path235-A and235-B remain unused during operation of the photonic circuit210.

FIG.2Bshows photonic circuit210in a second configuration where one laser (laser205-B) is used to power the four channels245. Specifically, laser205-B provides a light source to input port230-B. The light is split by the 1×2 splitter215and routed to the 2×2 splitter220A and 2×2 splitter220B via optical paths235-A and235-B. As shown inFIG.2B, laser205-B needs to provide enough optical power (theoretically double of the dual-laser case205-A/C) to mitigate the extra splitting loss.

As illustrated by the configurations shown in bothFIGS.2A and2B, photonic circuit210can be fully operational using a single laser or in a dual laser configuration. In these embodiments the lasers205-A/B/C are typical lasers used in optical communications. For example, they can be in the wavelength around 1310 nm or 1550 nm. Their wavelengths can be fixed or tunable. In this embodiment, the required laser output power depends specifically on the link requirements. As shown inFIGS.2A and2B, the required laser output power is in the range between 1 mW and 100 mW.

In various embodiments, the splitters may be formed in or disposed on the substrate of the photonic circuit. In these embodiments, the splitters may be formed in various waveguide platform, such as silicon, silicon oxide (SiOx), doped silicon oxide, silicon-nitride, or InGaAsP, polymer etc. In some embodiments, the splitters may be implemented from directional couplers, Y-branch, adiabatic coupler, multimode interferometer, etc.

In various embodiments, one or more of the lasers suitable for use with the PIC may be formed of any suitable semiconductor material(s), which may include elemental semiconductors (such as silicon) and/or compound semiconductors (such as group III-V semiconductor materials). Some non-limiting examples include gallium arsenide (GaAs), gallium phosphide (GaP), indium phosphide (InP), indium gallium phosphide (InGaP), aluminum gallium arsenide (AlGaAs), gallium nitride (GaN), indium gallium arsenide (InGaAs), indium gallium arsenide nitride (GaInNAs), gallium indium phosphide (GaInP), and so forth. In various embodiments, one or more of the laser sources suitable for use with the photonic circuit may be integrated with the photonic circuit or separate from the photonic circuit.

The embodiments shown inFIG.2AandFIG.2Bwith four output channels and three selectable input ports can be expanded to support number V of output channels, with number U of selectable input ports, and a variable number L of lasers (L<U). In various embodiments, the values for V, U, and L may be increased without limitation to scale a given photonic circuit design for higher channel count and other performance features. In various embodiments, C channels and/or lanes may be used with R modulators. In various embodiments, the value of C and R may be the same. C and R may range from 2 to 128 in some embodiments. In other embodiments, C and R are greater than or equal to 4. In other embodiments, C and R are greater than or equal to 8.

In various embodiments, a given photonic circuit may include W optical elements, wherein U, V, and W are integers greater than 1. For example, inFIG.2A, U=3, which includes channels230, V=4, which includes channels245, and W=3, which includes splitter215, and two splitters220. There are also V optical modulators225, wherein V is 4. In some embodiments, the number of lasers and the optical ports to which they connect is less than the number of output ports, such as ports245A-245D.

Refer now to the example embodiment ofFIG.3.FIG.3illustrates a photonic circuit implementing eight output channels (V=8), six input ports (U=6), and with either two or four lasers (L=2 or 4), in accordance with one or more aspects of the disclosure. As shown, the optical network interconnect300includes photonic circuit310. Photonic circuit310includes an optical network which includes 1×2 splitters320A and320B, 2×2 splitters (330A . . . D,330generally), and optionally, optical modulators (340-A . . . H,340generally). Photonic circuit310is enabled to receive optical signals from input ports (315-A . . . F,315generally). As shown, photonic circuit310includes U optical input channels, V optical output channels, and W optical elements, which in this instance, U=6, V=8, and W=14. For example, the U optical input channels includes input channels315, the V optical output channels include channels (345-A . . . H,345generally), and W optical elements includes splitters320, splitters330.

In addition, there are also V optical modulators340, wherein V is 8. In this embodiment, 1×2 splitter320A is capable of splitting optical signals received via input port315B into path325-A and path325-B. Path325-A is connected to 2×2 splitter330-A and path325-B is connected to 2×2 splitter330-B. Similarly, 1×2 splitter320B is capable of splitting an optical signal received via input port315-E into path325-C and path325-D. Path325-C is connected to 2×2 Splitter330-C and path325-D is connected to 2×2 splitter330-D. Additionally, 2×2 splitter330-A is connected to input port315-A, 2×2 splitter330-B is connected to input port315-C, 2×2 splitter330-C is connected to input port315-D, and 2×2 splitter330-D is connected to input port315-F. Each of the 2×2 splitters330split received optical signals into output channels335, which are directed toward each respective optical modulator340. Once optical signals from each output channel335is modulated at the optical modulators340, each respective optical modulator340outputs modulated optical signals via channels345.

In this embodiment, photonic circuit310is capable of being powered and fully operational when receiving optical signals from a subset of lasers (305-A . . . F,305generally). For example, in one embodiment, photonic circuit310can be implemented using lasers305-A,305-C,305-D, and305-F to create eight output channels345. In a second embodiment, the photonic circuit310can be implemented using lasers305-B and laser305-E to create eight output channels345.

Having thus described several aspects and embodiments of the technology of this application, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those of ordinary skill in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the technology described in the application. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described. In addition, any combination of two or more features, systems, articles, materials, and/or methods described herein, if such features, systems, articles, materials, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.

Also, as described, some aspects may be embodied as one or more methods. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

The phrase “and/or,” as used herein in the specification and in the claims, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases.

As used herein in the specification and in the claims, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified.

The terms “approximately” and “about” may be used to mean within ±20% of a target value in some embodiments, within ±10% of a target value in some embodiments, within ±5% of a target value in some embodiments, and yet within ±2% of a target value in some embodiments. The terms “approximately” and “about” may include the target value.

In the claims, as well as in the specification above, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” “composed of,” and the like are to be understood to be open-ended, i.e., to mean including but not limited to. The transitional phrases “consisting of” and “consisting essentially of” shall be closed or semi-closed transitional phrases, respectively.

Where a range or list of values is provided, each intervening value between the upper and lower limits of that range or list of values is individually contemplated and is encompassed within the disclosure as if each value were specifically enumerated herein. In addition, smaller ranges between and including the upper and lower limits of a given range are contemplated and encompassed within the disclosure. The listing of exemplary values or ranges is not a disclaimer of other values or ranges between and including the upper and lower limits of a given range.

Embodiments disclosed herein may be embodied as a system, method or computer program product. Accordingly, embodiments may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a “circuit,” “module,” or “system.” Furthermore, embodiments may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.