Co-packaged optical system with laser source and bidirectional laser medium

Abstract

An optical system can include a laser source including a laser source output port; an electro-optical (EO) transmitter (Tx) including a Tx input port and a Tx output port; a first polarization splitting beam splitter rotator (PSR) including a first port, a second port, and a third port; a second PSR including a fourth port, a fifth port, and a sixth port; and a polarization maintaining medium on an optical path between the second port and the fifth port. The laser source output port can be optically terminated at the first port. The second port can be optically terminated at the fifth port. The third port can be optically terminated at an output of the optical system. The Tx output port can be optically terminated at the fourth port. The fifth port can be optically terminated at the second port. The sixth port can be optically terminated at the Tx input port.

Description

[0001] Cross-references to related applications

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 386417, filed December 7, 2022, entitled “RETROGRADE INJECTION OFOPTICAL CARRIERS FOR CO-PACKAGED OPTICS”. The disclosure of the earlier application is considered part of this patent application and is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to co-packaged optics (CPO) systems, and more specifically, to CPO systems having a laser source and a bidirectional laser medium. Background Technology

[0004] Traditional optical interconnects, also known as pluggable optical modules (POMs), are inserted into the panels of devices such as servers, top-of-rack switches, or transport blades. The POMs are then connected to processors (e.g., central processing units (CPUs), graphics processing units (GPUs), application-specific integrated circuits (ASICs), tensor processing units (TPUs), neural processing units (NPUs), etc.) via electrical edge connectors on the device panel and traces on the motherboard. To address ever-increasing bandwidth demands, the data rate per connection (i.e., channel) has increased to, for example, gigabits per second (Gbps) per channel, and is expected to continue to increase in the future (e.g., doubling every two to four years). Here, the terms “transverse electric” (TE) and “transverse magnetic” (TM) do not imply any geometrically specific orientation that restricts optical polarization, but simply refer to the conventional means of two mutually orthogonal states of optical polarization. The component qualifiers “polarization,” “polarization separation,” and “polarization retention” are terms used with respect to the optical polarization of the TE and TM; therefore, components with such qualifiers typically have a characteristic axis that should be parallel or orthogonal to the chosen “transverse” direction; this is implied in the conventional usage of these terms. Summary of the Invention

[0005] In some embodiments, a co-packaged optical system includes: a laser source including a laser source output port; an electro-optical (EO) emitter (Tx) including a Tx input port and a Tx output port; a first polarization beam splitter rotator (PSR) including a first port, a second port, and a third port; a second PSR including a fourth port, a fifth port, and a sixth port; and a polarization-maintaining medium in the optical path between the second port of the first PSR and the fifth port of the second PSR, wherein the laser source output port is optically terminated at the first port of the first PSR, wherein the second port of the first PSR is optically terminated at the fifth port of the second PSR, wherein the third port of the first PSR is optically terminated at the output of the co-packaged optical system, wherein the Tx output port is optically terminated at the fourth port of the second PSR, wherein the fifth port of the second PSR is optically terminated at the second port of the first PSR, and wherein the sixth port of the second PSR is optically terminated at the Tx input port.

[0006] In some embodiments, an optical system includes: a laser source for providing an optical signal having a first polarization; a first polarization element for: receiving the optical signal from the laser source and providing the optical signal to a second polarization element via a polarization-maintaining medium; receiving a second modulated optical signal having a second polarization from the second polarization element via the polarization-maintaining medium; manipulating the polarization of the second modulated optical signal to generate an output signal having a first polarization; and providing the output signal to an output of the optical system; and a second polarization element for: receiving the optical signal from the first polarization element via the polarization-maintaining medium and providing the optical signal to a transmitter; receiving the first modulated optical signal having a first polarization from the transmitter; manipulating the polarization of the first modulated optical signal to generate a second modulated optical signal; and providing the second modulated optical signal to the first polarization element via the polarization-maintaining medium.

[0007] In some embodiments, a laser module includes: a laser source; a polarization element including: a first port for receiving an optical signal provided by the laser source, the optical signal having a first polarization; a second port for providing an output signal having the first polarization; a third port for: providing the optical signal received at the first port, wherein the optical signal will be provided to a polarization-maintaining medium, and receiving a modulated optical signal having a second polarization, wherein the optical signal will be received through the polarization-maintaining medium; and a set of optical elements for manipulating the polarization of the modulated optical signal received at the third port to generate the output signal provided at the second port.

[0008] In some embodiments, a method includes receiving transversely electrically (TE) polarized light at a first port of a first PSR; providing TE polarized light at a second port of the first PSR; receiving TE polarized light at a fifth port of the second PSR, the TE polarized light being received through a polarization-maintaining medium in an optical path between the first and second PSRs; providing TE polarized light at a sixth port of the second PSR; receiving modulated TE polarized light at a fourth port of the second PSR; rotating the polarization of the modulated TE polarized light by the second PSR to generate modulated transversely magnetically (TM) polarized light; providing modulated TM polarized light at the fifth port of the second PSR; receiving modulated TM polarized light at a second port of the first PSR, the modulated TM polarized light being received through a polarization-maintaining medium in an optical path between the first and second PSRs; rotating the polarization of the modulated TM polarized light by the first PSR to generate a TE polarized output signal; and providing the TE polarized output signal at a third port of the first PSR. Attached Figure Description

[0009] Figure 1 This is a schematic diagram illustrating an example of a conventional co-packaged optics (CPO) system.

[0010] Figure 2 This is a diagram illustrating an example of a CPO system including a laser source and a bidirectional laser medium.

[0011] Figure 3 It is shown Figure 2 A schematic diagram of an embodiment of the CPO system, including the laser source, the first polarization beam splitter (PSR), the second PSR, and the transmitter.

[0012] Figures 4A-4D This is a diagram illustrating an example embodiment of the laser source for the CPO system.

[0013] Figure 5 This is a diagram illustrating an example implementation of a laser source and a set of PSRs in a CPO system.

[0014] Figure 6A and 6B This is a diagram illustrating an example implementation of the PSR and transmitter in a CPO system.

[0015] Figure 7 This is a diagram of an example implementation of the CPO system described in this article.

[0016] Figure 8A and 8B This is a diagram illustrating an example embodiment of a CPO system including a semiconductor optical amplifier.

[0017] Figure 9 This is a flowchart of an example process related to the CPO system described in this article. Detailed Implementation

[0018] The following detailed description of exemplary embodiments is with reference to the accompanying drawings. The same reference numerals in different drawings may denote the same or similar elements.

[0019] At high data rates such as Gbps or higher, the motherboard traces and packages of devices (e.g., servers, top-of-rack switches, transport blades, etc.) and the electronic signal interconnects on electrical connectors introduce significant radio frequency (RF) losses. In some cases, these RF losses can be mitigated by strong digital signal processor (DSP) equalization. However, this DSP equalization comes at the cost of critical metrics such as cost, power consumption, and latency. Furthermore, long fan-out motherboard traces require on-board re-timers and expensive RF wiring. As a result, cost, power consumption, and latency increase. To address this challenge, co-packaged optics (CPO) systems can be used to integrate optical signal interconnects (e.g., optics included in the POM) with the processor into the same package, thereby replacing some of the lossy RF traces, the need for high equalization, and other peripherals.

[0020] While high-bit-rate connections to the processor can be achieved with a single pair of RF connections, an alternative is to use parallel, low-speed RF in-package interconnects (e.g., embedded multi-die interconnect bridges (EMIB), wire harnesses (BOW), universal chiplet interconnect fast (UCIe), etc.) and gearboxes (i.e., multiplexing) in the driver / receiver integrated circuits to achieve the desired rate. This internal gearbox reduces power consumption by using compact lumped-element capacitor devices. These devices can be, for example, silicon photonics microring modulators or segmented / short / lumped-element Mach-Zehnder (MZ) modulators (instead of traveling-wave-terminated MZ modulators). These solutions can be used in applications such as digital RF beamforming radar, artificial intelligence (AI) and machine learning (ML) clusters, or high-performance computing (HPC) communication standards such as InfiniBand. In general, these improvements require packaging the CPO solution with the processor and introduce challenges such as meeting the processor's bandwidth density (e.g., one-dimensional (1D) / coastline and two-dimensional (2D) / area) and operating with high reliability at high temperatures. These two requirements led to the development of separating the transmitter and receiver optics from the laser source. The laser source may in some cases be referred to as an external laser / source (ELS) or a remote laser / source. However, this solution requires attaching additional laser fiber to the transmitter, which expands the device's coverage area, limits bandwidth density, and reduces device reliability (e.g., by adding additional interfaces).

[0021] Figure 1 This is a diagram illustrating an example of a conventional CPO system 100. (As shown...) Figure 1As shown, a conventional CPO system includes a motherboard on which two laser sources and a multi-chip module (MCM) are connected. As illustrated, the MCM includes a processor, one or more memories, two electro-optical transmitters (EO Tx), and two opto-receivers (OE Rx), with a given EO Tx / OE Rx pair located on the same chip. Further, the CPO system includes two transmitter / laser fiber array units (Tx / L FAU) to couple light from / to the EO Tx, and two receiver fiber array units (Rx FAU) to couple light to the OE Rx. Optical connections between a given laser source and its associated EO Tx are provided via a series of connectors (e.g., one or more multi-fiber push (MPO) connectors) and polarization-maintaining (PM) fibers. Similarly, optical connections between a given EO Tx and its associated Tx outputs are provided via a series of connectors and PM fibers. Furthermore, optical connections between a given OE Rx and its associated Rx inputs are provided via a series of connectors and PM fibers.

[0022] In practice, the architecture of the laser source depends on the requirements of the EO Tx and OE Rx. There are various possible laser source architectures, and the use of a given laser source architecture can depend on factors such as the number of wavelengths, power per wavelength, eye safety requirements in the output fiber, etc., as defined in a given application. Given these various possible laser source architectures, there are various possible architectures for the EO Tx and OE Rx, which can include one or more on-chip multiplexers, demultiplexers, or power dividers (e.g., enabling laser power to be shared among multiple modulators), and can provide polarization multiplexing at the output.

[0023] Although there are many arrangements of the above implementations, they all share the common feature of having laser input fiber, transmitting fiber, and receiving fiber at the interface of the CPO package. If these fibers are edge-coupled or vertically coupled to optical devices (e.g., silicon photonic integrated circuits Tx / Rx) in a 1D arrangement, the shore bandwidth density of the optical devices is limited by the fiber spacing, the number of fibers required per transceiver, the number of wavelengths per fiber, and the bandwidth of each fiber.

[0024] As an example, with a bump pitch of 36 micrometers (μm) or 50 μm (electrical interface mesh), a processor with 25 Gbps signaling and a four-layer grounding signaling mode has a coastline density of 0.92 trillion bits per second per millimeter (Tbps / mm) or 0.66 Tbps / mm, respectively, which requires a 127 μm fiber pitch and shared laser or polarization multiplexed transmission output. Recall... Figure 1These fibers will branch within the chassis and, in many cases, remain polarized, increasing costs and limiting equipment availability. It's worth noting that the demand for fiber density is expected to double over time (e.g., every 24 to 48 months for data center / HPC ASICs, and every 12 to 18 months for AI / ML cluster ASICs). Given these requirements and observations, reducing the number of fibers in a CPO package is a key parameter for achieving CPO package scalability.

[0025] Some embodiments described herein provide a CPO system with a laser source and a bidirectional laser medium. In some embodiments, the CPO system includes a laser source and an EO Tx, the laser source including a laser source output port, and the EO Tx including a Tx input port and a Tx output port. The optical system also includes a first polarization beam splitter rotator (PSR) with multiple ports and a second PSR with multiple ports. The optical system also includes a polarization-maintaining medium in the optical path between one port of the first PSR and one port of the second PSR. In some embodiments, the CPO system allows the laser fiber and the Tx fiber to be combined into a single fiber, making the flow in the optical path between the laser and the EO Tx bidirectional. Therefore, the CPO system described herein reduces the number of fibers required in a CPO system, thereby reducing cost and increasing fiber density (e.g., compared to conventional CPO systems). Furthermore, the CPO system described herein reduces the number of fiber branches and cabling within the CPO system chassis, thereby reducing the cost and complexity of the CPO system. More details are provided below.

[0026] Figure 2 This is a diagram illustrating an example of a CPO system 200 including a laser source and a bidirectional laser medium. (See diagram for example.) Figure 2 As shown, the CPO system 200 may include a motherboard 202 on which one or more laser sources 204 (e.g., two laser sources 204) and an MCM 208 are connected. As shown, the MCM 208 may include a processor 210, one or more memories 212, one or more EOTx 216 (e.g., two EOTx 216), and one or more OE Rx 218 (e.g., two OE Rx 218). In some embodiments, a given pair of EOTx 216 and OE Rx 218 may reside on the same chip, such as... Figure 2 As shown. Further illustrated, the CPO system 200 may include one or more Tx / L FAU220s to couple light from / to the EO Tx216, and one or more Rx FAU222s to couple light to the OE Rx218. The optical connection between the given laser source 204 and the associated EO Tx216 is via a series of connectors (e.g., one or more MPO connectors, provided by…) Figure 2The shaded rectangle in the diagram represents the input) and one or more PM media 224 (e.g., one or more PM optical fibers) are provided. Furthermore, an optical connection between a given OE Rx218 and the associated Rx input can be provided via a series of connectors and PM optical fibers 226.

[0027] As further shown, the CPO system 200 includes PSR 206 and PSR 214. A PSR (e.g., PSR 206, PSR 214) is an optical component capable of performing polarization separation and / or polarization rotation on an optical signal. "Polarization separation" refers to the separation of an optical signal to generate two optical signals comprising light with orthogonal polarization. For example, a PSR can separate optical signals to generate a transversely electrically (TE) polarized optical signal and a transversely magnetically (TM) polarized optical signal. "Polarization rotation" refers to rotating the polarization axis of a (linearly) polarized optical signal by a certain angle. For example, a PSR can rotate the polarization axis of a TE polarized optical signal to generate a TM polarized optical signal, or it can rotate the polarization axis of a TM polarized optical signal to generate a TE polarized optical signal. Generally, a PSR bidirectionally connects a pair of optical signals polarized (either of which may be absent) between: (a) one side at the same location (port) and with different orientations; and (b) the opposite sides at different locations (ports) and with the same orientation.

[0028] In some embodiments, as shown in CPO system 200, PSR 206 and PSR 214 are located in the optical path between laser source 204 and Tx 216. That is, in some embodiments, PSR 206 and PSR 214 are arranged such that light propagating from laser source 204 to Tx 216 passes through PSR 206 and PSR 214, and light propagating from Tx 216 to laser source 204 passes through PSR 214 and PSR 206. In some embodiments, PSR 206 may be included in laser source 204 (e.g., PSR 206 and laser source 204 may be integrated on the same chip or in the same package). Alternatively, PSR 206 may be separate from laser source 204. In some embodiments, PSR 214 may be included in Tx 216 (e.g., PSR 214 and Tx 216 may be integrated on the same chip or in the same package). Alternatively, PSR 214 may be separate from Tx 216. It is worth noting that PSR206 and PSR214 can be used in CPO system 200 because PSR206 and PSR214 can be integrated into a silicon photonics platform with performance matching that of discrete counterparts, which is not the case for other types of components (such as reflective modulators and circulators) that are capable of bidirectional operation as described herein.

[0029] In the CPO system 200, by providing the optical signal output from laser source 204 as an uplink to Tx216 and the optical signal output from Tx216 as a downlink to laser source 204, PSRs 206 and 214 enable the laser medium (e.g., the fiber associated with providing light from laser source 204 to Tx216) and the Tx medium (e.g., the fiber associated with providing light from Tx216 to laser source 204) to be combined into a single medium (e.g., a single PM fiber). Therefore, PSRs 206 and 214 allow light to propagate in both directions (i.e., bidirectionally) between laser source 204 and Tx216 within the same medium (e.g., the same PM medium 224). In this way, the CPO system 200 reduces the number of fibers, thereby reducing cost and increasing fiber density (e.g., compared to conventional CPO systems). Furthermore, the CPO system 200 reduces the number of fiber branches and cabling within the chassis, thereby reducing cost and complexity (e.g., compared to conventional CPO systems). The CPO system 200 differs from traditional CPO systems in that the laser fiber and Tx fiber are separate fibers, each carrying light propagating in a single direction (e.g., uplink or downlink).

[0030] As mentioned above, Figure 2 This is provided as an example. Other examples may differ from those provided. Figure 2 As described. Figure 2 The number and arrangement of components shown are provided as an example. In reality, there may be more... Figure 2 This shows more components, fewer components, different components, or components with different arrangements. Furthermore, Figure 2 The two or more components shown can be implemented within a single component, or Figure 2 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 2 The set of components shown (e.g., one or more components) can perform what is described as being made by Figure 2 The other set of components shown performs one or more functions.

[0031] Figure 3 It is shown Figure 2 A schematic diagram of an embodiment of the laser source 204, PSR 206, PSR 214, and Tx 216 of the CPO system 200 shown. Figure 3 As shown, laser source 204 includes laser source output port 204o, and Tx 216 includes Tx input port 216i and Tx output port 216o. As further shown, PSR 206 includes a first port 206i, a second port 206io, and a third port 206o, and PSR 214 includes a fourth port 214i, a fifth port 214io, and a sixth port 214o.

[0032] In some implementations, such as Figure 3 As shown, PM medium 224 is located in the optical path between the second port 206io of PSR 206 and the fifth port 214io of PSR 214. In some embodiments, PM medium 224 includes one or more optical components (e.g., one or more optical fibers) designed to maintain the polarization of light propagating along PM medium 224.

[0033] In some embodiments, the laser source output port 204o optically terminates at the first port 206i of PSR 206. In some embodiments, the second port 206io of PSR 206 is optically terminated at the fifth port 214io of PSR 214. In some embodiments, the third port 206o of PSR 206 is optically terminated at the output of CPO system 200 (not shown). In some embodiments, the Tx output port 216o is optically terminated at the fourth port 214i of PSR 214. In some embodiments, the fifth port 214io of PSR 214 is optically terminated at the second port 206io of PSR 206. In some embodiments, the sixth port 214o of PSR 214 is optically terminated at the Tx input port 216i.

[0034] exist Figure 3 In the example operation of the CPO system 200 shown, the laser source 204 provides an optical signal with a first polarization (e.g., a TE-polarized optical signal). Here, the laser source 204 provides the optical signal via the laser source output port 204o, such that the optical signal is coupled to the first port 206i of the PSR 206.

[0035] PSR206 receives optical signals from laser source 204 and provides the optical signals to PSR214 through PM medium 224. Here, PSR206 provides optical signals via second port 206io, so that the optical signals are coupled to fifth port 214io.

[0036] PSR214 receives optical signals from PSR206 via PM medium 224 and provides the optical signals to Tx216. Here, PSR214 provides optical signals via sixth port 214o, so that the optical signals are coupled to Tx input port 216i.

[0037] Tx216 receives the optical signal provided by PSR214, modulates the optical signal to generate a first modulated optical signal with a first polarization (e.g., a TE polarization modulated optical signal), and provides the first modulated optical signal to PSR214. Here, Tx216 provides the first modulated optical signal via Tx output port 216o, such that the first modulated optical signal is coupled to the fourth port 214i.

[0038] PSR214 receives a first modulated optical signal from Tx216, manipulates (e.g., rotates) the polarization of the first modulated optical signal to generate a second modulated optical signal (e.g., a TM polarization modulated optical signal), and provides the second modulated optical signal to PSR206 via PM medium 224. Here, PSR214 provides the second modulated optical signal via fifth port 214io, such that the second modulated optical signal is coupled to second port 206io.

[0039] PSR206 receives a second modulated optical signal from PSR214 via PM224, manipulates the polarization of the second modulated optical signal to generate an output signal with a first polarization (e.g., a TE-polarized output signal), and provides the output signal to the output of CPO system 200. Here, PSR206 provides the output signal through a third port 206, such that the output signal is coupled to the output of CPO system 200.

[0040] In fact, by Figure 3 The operation implemented by the CPO system 200 shown eliminates the need for non-reciprocal media (such as circulators) and can be fabricated using easily integrated components such as PSRs, MZ modulators, or micro-ring modulators. Furthermore, Figure 3 The CPO system 200 shown provides the flexibility to enable multi-wavelength solutions required in some applications (such as data center / HPC or AI / ML architectures) while increasing shoreline density.

[0041] As mentioned above, Figure 3 This is provided as an example. Other examples may differ from those provided. Figure 3 As described. Figure 3 The number and arrangement of components shown are provided as an example. In reality, there may be more... Figure 3 This shows more components, fewer components, different components, or components with different arrangements. Furthermore, Figure 3 The two or more components shown can be implemented within a single component, or Figure 3 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 3 The set of components shown (e.g., one or more components) can perform what is described as being made by Figure 3 The other set of components shown performs one or more functions.

[0042] Figures 4A-4DThis diagram illustrates an example embodiment of laser source 204. In some embodiments, laser source 204 may be, for example, a single-wavelength continuous-wave (CW) laser source, a multi-wavelength single-output CW laser source, or a multi-wavelength multi-output CW laser source. In some embodiments, laser source 204 may be configured to generate N (N≥1) wavelengths (λ) of light, and may provide one or more of the N wavelengths via M (M≥1) output optical fibers. In practice, the number N and the number M are independent of each other. In some embodiments, N may be in the range of, for example, 1 to 32. In some embodiments, M may be in the range of, for example, 1 to 32.

[0043] Figure 4A A first example implementation of the laser source 204 is shown. Figure 4A As shown, the laser source 204 may include a power monitor 402, a laser array 404 generating light of N wavelengths, and N output optical fibers. Here, each of the N output optical fibers can carry one of the N wavelengths of light (e.g., such that one wavelength is provided via each of the N output optical fibers). Figure 4A In the example shown, N equals M. In some implementations, Figure 4A The laser source 204 shown can be a single-wavelength high-power CW laser (e.g., when N=M=1).

[0044] Figure 4B A second example implementation of the laser source 204 is shown. (As...) Figure 4B As shown, the laser source 204 may include a power monitor 402, a laser array 404 that generates light of N wavelengths, an N×1 multiplexer (MUX) 406, and a single output fiber (e.g., M=1). Here, the output fiber can carry light of N wavelengths. Figure 4B The laser source 204 shown can be, for example, a multi-wavelength coarse wavelength division multiplexing (CWDM) or dense wavelength division multiplexing (DWDM) single-output CW laser source.

[0045] Figure 4C A third example implementation of the laser source 204 is shown. (As...) Figure 4C As shown, the laser source 204 may include a power monitor 402, a laser array 404 that generates light of N wavelengths, an N×1 MUX 406, a 1×M beam splitter 408, and M output optical fibers. Here, each of the M output optical fibers can carry light of N wavelengths. Figure 4C The laser source 204 shown can be, for example, a multi-wavelength CWDM or DWDM multi-output CW laser source.

[0046] Figure 4D A fourth example implementation of the laser source 204 is shown. (As...) Figure 4DAs shown, the laser source 204 may include a power monitor 402, a laser array 404 that generates light of N wavelengths, an N×M broadband beam splitter 410, and M output optical fibers. Here, each of the M output optical fibers can carry light of N wavelengths. Figure 4D The laser source 204 shown can be, for example, a multi-wavelength CWDM or DWDM multi-output CW laser source.

[0047] As mentioned above, Figures 4A-4D This is provided as an example. Other examples may differ from those provided. Figures 4A-4D As described. Figures 4A-4D The number and arrangement of components shown are provided as an example. In reality, with... Figures 4A-4D Compared to the diagram shown, there may be additional components, fewer components, different components, or components with different arrangements. Furthermore, Figures 4A-4D The two or more components shown can be implemented within a single component, or Figures 4A-4D The single component shown can be implemented as multiple distributed components. Alternatively, Figures 4A-4D The set of components shown (e.g., one or more components) can perform what is described as being made by Figures 4A-4D The other set of components shown performs one or more functions.

[0048] Figure 5 This is a diagram illustrating an example embodiment 500 of a CPO system 200, showing a laser source 204 and a set of M PSRs 206 (e.g., PSRs 206-1 to PSRs 206-M). In some embodiments, Figure 5 The laser source 204 shown can have the following characteristics: Figures 4A-4D The architecture is shown in any of the figures. As described in this article, this PSR206 group is capable of bidirectional laser output and Tx input.

[0049] like Figure 5 As shown, in one example, laser source 204 can generate TE-polarized light of N wavelengths (e.g., laser source 204 is an NλTE laser). Laser source 204 provides TE-polarized light signals to each of M PSRs 206. Here, a given TE-polarized light signal can include one or more of the N wavelengths of light (e.g., depending on the architecture of laser source 204). A given PSR 206 receives a corresponding one of the M TE-polarized light signals and provides the TE-polarized light signal through the corresponding bidirectional laser output / Tx input (in... Figure 5 (Identified as "TE laser output" in Chinese). Therefore, as... Figure 5 As shown, the CPO system 200 may include M laser outputs / Tx inputs. In some embodiments, the medium through which TE polarized optical signals are provided (and via which TM polarized modulated optical signals are received, as described below) includes PM medium 224.

[0050] As further shown, the given PSR206 is configured to receive M TM polarization modulated optical signals via the same bidirectional laser output / Tx input (in Figure 5 The corresponding one in the (labeled "TM Tx Input") is used. Here, the TM polarization modulated optical signal can include one or more of light of N wavelengths. After the Tx216 modulates the TE polarization optical signal, the TM polarization modulated optical signal is provided by the PSR214 to the PSR206 (e.g., referenced). Figure 6A and 6B The PSR206 receives the TM polarization modulated optical signal, performs polarization separation to separate the TM polarization modulated optical signal from the TE polarization light propagating through the PSR, and manipulates the polarization of the TM polarization modulated optical signal to generate a TE polarization output signal. Then, the PSR206 provides the TE polarization output signal through one of the M Tx outputs of the CPO system 200.

[0051] As mentioned above, Figure 5 This is provided as an example. Other examples may differ from those provided. Figure 5 As described. Figure 5 The number and arrangement of components shown are provided as an example. In reality, with... Figure 5 Compared to the diagram shown, there may be additional components, fewer components, different components, or components with different arrangements. Furthermore, Figure 5 The two or more components shown can be implemented within a single component, or Figure 5 The single component shown can be implemented as multiple distributed components. Alternatively, Figure 5 The set of components shown (e.g., one or more components) can perform what is described as being made by Figure 5 The other set of components shown performs one or more functions.

[0052] Figure 6A and 6B These are figures illustrating example embodiments 605 and 610 of PSR 214 and Tx 216 in CPO system 200, respectively. In some embodiments, PSR 214 is one of a set of M PSR 214s, wherein each of the M PSR 214s is connected via PM medium 224 to a corresponding PSR 206 in a set of M PSR 206s (e.g., refer to...). Figure 5 (Description). Therefore, in some embodiments, the CPO system 200 may include M PSR 214s and M Tx 216s. As described herein, this set of PSR 214s enables bidirectional laser output and Tx input.

[0053] For reference Figure 5The PSR214 can receive TE polarized light signals from the PSR206 via bidirectional laser output / Tx input (e.g., via PM medium 224). Figure 6A and 6B (Identified as "TE laser input" in Chinese). Figure 6A and 6B As shown, PSR214 provides TE polarized light signals to Tx216. In some embodiments, Tx216 may be a WDM or a single CW transmitter using a single laser fiber input, and includes a 1×N demultiplexer (DEMUX) 602, a set of N TE modulators 604, and an N×1 MUX 606, examples of which are shown in Figure 6A As shown in [the diagram]. In some embodiments, the Tx216 can be a WDM or single CW transmitter that uses a single laser fiber input and includes a modulator group 608 for TE polarization, an example of which is [illustrated in the diagram]. Figure 6B As shown in the figure. In some embodiments, modulator group 608 may be, for example, a ring resonator-based modulator group or a Mach-Zehnder modulator group. In some embodiments, Tx216 modulates the TE polarized optical signal to generate a TE polarized modulated optical signal and provides the TE polarized modulated optical signal to PSR214.

[0054] The PSR214 receives the TE polarization-modulated optical signal and manipulates its polarization to generate a TM polarization output signal. The PSR214 then provides the TM polarization-modulated optical signal via the same bidirectional laser output / Tx input (in... Figure 6A and 6B (Identified as "TM Tx Output"). Here, the TM polarization modulated optical signal can include one or more of N wavelengths of light.

[0055] As mentioned above, providing Figure 6A and 6B As an example. Other examples may differ from those regarding... Figure 6A and 6B As described. Figure 6A and 6B The number and arrangement of components shown are provided as an example. In reality, with... Figure 6A and 6B Compared to the diagram shown, there may be additional components, fewer components, different components, or components with different arrangements. Furthermore, Figure 6A and 6B The two or more components shown can be implemented within a single component, or Figure 6A and 6B The single component shown can be implemented as multiple distributed components. Alternatively, Figure 6A and 6BThe set of components shown (e.g., one or more components) can perform what is described as being made by Figure 6A and 6B The other set of components shown performs one or more functions.

[0056] Figure 7 This is a diagram of an example implementation 700 of the CPO system 200. Example implementation 700 illustrates an example of a bidirectional CPO transceiver architecture that can be used with eight wavelength channels (e.g., N=8). In some implementations, such as... Figure 7 As shown, Tx216 and Rx218 can be included in the MCM208 (e.g., on the same chip). For clarity, Figure 7 Only one of the M transceivers is shown (e.g., a Tx216 / Rx218 pair). In some embodiments, the Rx218 is capable of converting the input optical signal (e.g., received by the CPO system 200) into an electrical signal. In practice, example embodiment 700 may include multiple PSR206s, multiple PSR214s, and multiple transceivers, each using a corresponding output fiber (i.e., M can be greater than 1). In example embodiment 700, the Rx218 includes a 1×8 ring resonator filter bank and eight photodetectors (PDs) 704; however, other embodiments of the Rx218 may be used.

[0057] As mentioned above, Figure 7 This is provided as an example. Other examples may differ from those provided. Figure 7 As described.

[0058] In fact, the limitations of the CPO system 200 are (1) polarization separation between the optical signal generated by the laser source 204 and the output optical signal, (2) photonic components (e.g., PSR206 and PSR214) are added to the photonic integrated circuit (PIC) of the laser source 204 and Tx216, and (3) single polarization is used for transmission and each output single fiber laser input.

[0059] The polarization separation between the optical signal generated by laser source 204 and the output optical signal is related to the polarization extinction ratio and crosstalk between PSRs 206 and 214, the waveguide-fiber coupler in CPO system 200, and the PM fiber in CPO system 200. Generally, if an undesirable polarization rotation exists between PSRs 214 and 206, optical power is dumped into the optical path of laser source 204, which can lead to instabilities (e.g., side-mode suppression ratio) or increased noise (e.g., relative intensity noise). However, these effects can be prevented by including an isolator in the optical path between laser source 204 and PSR 206. Therefore, in some embodiments, CPO system 200 includes an isolator located in the optical path between laser source 204 and PSR 206. In some embodiments, the isolator is used to at least partially isolate laser source 204 from a portion of a modulated optical signal having a specific polarization (e.g., TE polarization). It is worth noting that isolators are typically used in applications (e.g., in single-mode data center / HPC links) to avoid instabilities caused by reflections and feedback; therefore, adding an isolator does not increase the cost or complexity of the CPO system 200. Furthermore, while quantum well lasers are sensitive to back reflections, which can lead to increased relative intensity noise or instability, quantum dot lasers (QDLs) are robust to back reflections. In some implementations, QDLs can be used to avoid the need for isolators in the CPO system 200.

[0060] Furthermore, adding optical components (such as one or more PSR206s and one or more PSR214s) to the CPO system 200 may introduce insertion loss into the overall link budget. However, by leading the fiber directly out of the laser source 204, at least one fiber optic connector and branch cable within the chassis are removed, which at least partially offsets the insertion loss, while reducing cost, increasing shoreline density, and increasing panel bandwidth density. In some embodiments, to mitigate the loss due to adding optical components to the Tx216, the CPO system 200 may include an optical amplifier (e.g., a semiconductor optical amplifier (SOA)).

[0061] Figure 8A and 8B Example implementations 800 and 820 of a CPO system 200 including SOA802 are shown respectively. In some implementations, such as Figure 8A and 8BAs shown, SOA802 can be located in the optical path between the PSR206 and the output of the CPO system 200 (e.g., between the PSR206 and the Tx output fiber). In some embodiments, SOA802 may include an array of SOAs (e.g., M SOAs), each associated with one of the M Tx216 outputs. In some embodiments, SOA802 is used to amplify the output signal provided by the PSR206. In some embodiments, SOA802 can overcome limitations on transmit output power and / or reduce total power consumption when, for example, the Tx216 becomes nonlinear at high input power (e.g., when the Tx216 includes a microring or resonant modulator), or when the additional SOA power is less than the additional power required for all WDM lasers to increase their output power. In some embodiments, the use of SOA802 enables various implementations, such as a high-bandwidth MZ modulator with a heavily doped silicon photonic pn junction and a metal-oxide-semiconductor capacitor (MOSCAP), or a lossy heavily doped ring modulator for the transmitter PIC, to reduce power consumption. In this scenario, the SOA802 can be used to achieve increased data rates without increasing power consumption. In some implementations, the CPO system 200 may include an isolator after the SOA802.

[0062] As mentioned above, Figure 8A and 8B This is provided as an example. Other examples may differ from those provided. Figure 8A and 8B As described.

[0063] Figure 9 This is a flowchart of an example process 900 related to the CPO system 200 described herein. In some implementations, Figure 9 One or more process frames are executed by one or more components of the CPO system 200, such as PSR206 or PSR214, as described below.

[0064] like Figure 9 As shown, process 900 may include receiving TE-polarized light at a first port of a first polarization beam splitter (PSR) (box 905). For example, the first PSR (e.g., PSR 206) may receive TE-polarized light at a first port of the first PSR, as described above.

[0065] like Figure 9 As further shown, process 900 may include providing TE-polarized light at a second port of the first PSR (box 910). For example, the first PSR may provide TE-polarized light at a second port of the first PSR, as described above.

[0066] like Figure 9The diagram further illustrates that process 900 may include receiving TE-polarized light at a fifth port of the second PSR, the TE-polarized light being received via a polarization-maintaining medium in the optical path between the first PSR and the second PSR (block 915). For example, the second PSR (e.g., PSR 214) may receive TE-polarized light at its fifth port, the TE-polarized light being received via a polarization-maintaining medium (e.g., PM medium 224) in the optical path between the first PSR and the second PSR, as described above.

[0067] like Figure 9 As further shown, process 900 may include providing TE-polarized light at the sixth port of the second PSR (box 920). For example, the second PSR may provide TE-polarized light at the sixth port of the second PSR as described above.

[0068] like Figure 9 As further shown, process 900 may include receiving modulated TE-polarized light at the fourth port of the second PSR (box 925). For example, the second PSR may receive modulated TE-polarized light at the fourth port of the second PSR, as described above.

[0069] like Figure 9 As further shown, process 900 may include rotating the polarization of the modulated TE polarized light to generate modulated TM polarized light (box 930). For example, a second PSR may rotate the polarization of the modulated TE polarized light to generate modulated TM polarized light, as described above.

[0070] like Figure 9 As further shown, process 900 may include providing modulated TM-polarized light at the fifth port of the second PSR (box 935). For example, the second PSR may provide modulated TM-polarized light at the fifth port of the second PSR, as described above.

[0071] like Figure 9 As further shown, process 900 may include receiving modulated TM-polarized light at a second port of the first PSR, the modulated TM-polarized light being received via a polarization-maintaining medium in the optical path between the first PSR and the second PSR (block 940). For example, the first PSR may receive modulated TM-polarized light at a second port of the first PSR, the modulated TM-polarized light being received via a polarization-maintaining medium in the optical path between the first PSR and the second PSR, as described above.

[0072] like Figure 9 As further shown, process 900 may include rotating the polarization of the modulated TM-polarized light to generate a TE-polarized output signal (block 945). For example, the first PSR may rotate the polarization of the modulated TM-polarized light to generate a TE-polarized output signal, as described above.

[0073] like Figure 9 As further shown, process 900 may include providing a TE polarization output signal at a third port of the first PSR (block 950). For example, the first PSR may provide a TE polarization output signal at its third port as described above.

[0074] Process 900 may include additional implementations, such as any single implementation or any combination of implementations of one or more other processes described below and / or described elsewhere herein.

[0075] although Figure 9 An example block diagram of process 900 is shown, but in some implementations, process 900 includes more than Figure 9 The boxes depicted may include more boxes, fewer boxes, different boxes, or boxes with different arrangements. Alternatively, two or more boxes in process 900 may be executed in parallel.

[0076] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations can be made based on the foregoing disclosure, or modifications and variations can be obtained from practice of the embodiments. For example, while some embodiments described herein are described in the context of a CPO system that transmits a TE-polarized output generated from a TM-polarized modulated optical signal, wherein the TM-polarized modulated optical signal is generated from a TE-polarized optical signal provided by a laser source, other embodiments are also possible. For example, in some CPO systems, the use of TE-polarized light and TM-polarized light can be interchanged. That is, a CPO system can be configured to transmit a TM-polarized output generated from a TE-polarized modulated optical signal, wherein the TE-polarized modulated optical signal is generated from a TM-polarized optical signal provided by a laser source. In other words, in some CPO systems, the use of TE-polarized light and TM-polarized light can be reversed (compared to the examples described herein) without loss of functionality. Furthermore, any embodiments described herein can be combined unless the foregoing disclosure expressly provides reasons why one or more embodiments cannot be combined.

[0077] Even if specific combinations of features are stated in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of various embodiments. In fact, many of these features can be combined in ways not specifically stated in the claims and / or not disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of various embodiments includes combinations of each dependent claim with each other claim in the claim group. As used herein, the phrase “at least one” referring to a series of items means any combination of those items, including single members. For example, “at least one of a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination of multiple identical items.

[0078] Unless explicitly stated otherwise, no element, action, or instruction used herein should be construed as critical or necessary. Furthermore, as used herein, the articles “a” and “one” are intended to include one or more items and may be used interchangeably with “one or more.” Furthermore, as used herein, the article “the” is intended to include one or more items associated with the article “the” and may be used interchangeably with “the one or more.” Furthermore, as used herein, the term “group” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items) and may be used interchangeably with “one or more.” If referring to only one item, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “having” and the like are intended to be open-ended terms. Furthermore, the phrase “based on” is intended to mean “at least partially based on” unless explicitly stated otherwise. Furthermore, as used herein, the term “or” is inclusive in a series of uses and may be used interchangeably with “and / or” unless explicitly stated otherwise (e.g., if used in conjunction with “any” or “only one”). Furthermore, for ease of description, spatial relative terms such as “below,” “down,” “above,” “up,” etc., may be used here to describe the relationship of one element or feature to another element or feature shown in the figure. In addition to the orientations shown in the figure, spatial relative terms are intended to cover different orientations of devices, equipment, and / or elements in use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatial relative descriptors used herein shall be interpreted accordingly.

Claims

1. A co-packaged optical system, comprising: Laser source including laser source output port; The electro-optical EO transmitter Tx includes a Tx input port and a Tx output port; The first polarization beam splitter rotator (PSR) includes a first port, a second port, and a third port; The second PSR includes the fourth, fifth, and sixth ports; as well as Polarization-maintaining medium in the optical path between the second port of the first PSR and the fifth port of the second PSR. The laser source output port is optically terminated at the first port of the first PSR. Wherein, the second port of the first PSR is optically terminated at the fifth port of the second PSR. The third port of the first PSR is connected to the output optical terminal of the co-packaged optical system. The Tx output port is optically terminated at the fourth port of the second PSR. Wherein, the fifth port of the second PSR is optically terminated at the second port of the first PSR, and The sixth port of the second PSR is optically terminated at the Tx input port.

2. The co-packaged optical system according to claim 1 further includes an optical amplifier located in the optical path between the third port of the first PSR and the output of the co-packaged optical system.

3. The co-packaged optical system according to claim 1 further includes an isolator located in the optical path between the laser source output port and the first port of the first PSR.

4. The co-packaged optical system of claim 1, further comprising an opto-electronic (OE) receiver (Rx), wherein, The EO Tx and the OE Rx are included in a multi-chip module (MCM).

5. The co-packaged optical system of claim 1, wherein, The laser source includes one of a single-wavelength continuous wave (CW) laser source, a multi-wavelength single-output CW laser source, or a multi-wavelength multi-output CW laser source.

6. The co-packaged optical system of claim 1, wherein, The EO Tx includes a demultiplexer located at the Tx input port, a multiplexer located at the Tx output port, and a set of modulators located on the optical path between the demultiplexer and the multiplexer.

7. The co-packaged optical system of claim 1, wherein, The EO Tx includes a ring resonator-based modulator group or a Mach-Zehnder modulator group in the optical path between the Tx input port and the Tx output port.

8. An optical system comprising: A laser source, used to provide an optical signal with a first polarization; as well as The first polarization element is used for: The optical signal is received from the laser source and provided to the second polarization element via a polarization-maintaining medium. A second modulated optical signal, having a second polarization, is received from the second polarization element via the polarization-maintaining medium. The polarization of the second modulated optical signal is manipulated to generate an output signal having the first polarization. Provide the output signal to the output of the optical system; and The second polarization element is used for: The optical signal is received from the first polarization element via the polarization-maintaining medium, and the optical signal is provided to the transmitter. A first modulated optical signal with a first polarization is received from the transmitter. Manipulate the polarization of the first modulated optical signal to generate the second modulated optical signal, and The second modulated optical signal is provided to the first polarization element via the polarization-maintaining medium.

9. The optical system of claim 8 further includes an optical amplifier for amplifying the output signal provided by the first polarizing element.

10. The optical system of claim 8, further comprising an isolator for at least partially isolating the laser source from a portion of the second modulated optical signal having the first polarization.

11. The optical system of claim 8, further comprising a receiver for converting the input optical signal to an electrical signal, wherein, The transmitter and the receiver are included in a multi-chip module (MCM).

12. The optical system of claim 8, wherein, The laser source includes one of a single-wavelength continuous wave (CW) laser source, a multi-wavelength single-output CW laser source, or a multi-wavelength multi-output CW laser source.

13. The optical system of claim 8, wherein, The transmitter is used for: Receive the optical signal provided by the second polarization element; Modulate the optical signal to generate the first modulated optical signal; and The first modulated optical signal is provided to the second polarization element.

14. The optical system of claim 8, wherein, The first polarization and the second polarization are mutually orthogonal optical polarization states.

15. A laser module, comprising: Laser source; as well as Polarizing elements, including: A first port is used to receive an optical signal provided by the laser source, the optical signal having a first polarization; The second port is used to provide an output signal with the first polarization; The third port is used for: Provide the optical signal received at the first port, wherein the optical signal will be provided to the polarization-maintaining medium, and Receive a modulated optical signal having a second polarization, wherein the optical signal will be received via the polarization-maintaining medium; and A set of optical elements is used to manipulate the polarization of the modulated optical signal received at the third port to generate the output signal provided at the second port.

16. The laser module of claim 15 further includes an optical amplifier located in the optical path, wherein the optical signal is provided by the second port of the polarizing element in the optical path.

17. The laser module of claim 15, further comprising an isolator located in the optical path between the laser source and the first port of the polarizing element.

18. The laser module of claim 15, wherein, The laser source includes one of a single-wavelength continuous wave (CW) laser source, a multi-wavelength single-output CW laser source, or a multi-wavelength multi-output CW laser source.

19. The laser module according to claim 15, wherein, The first polarization and the second polarization are mutually orthogonal optical polarization states.

20. The laser module of claim 15, wherein, The optical signal is provided to the electro-optical EO transmitter Tx, and the modulated optical signal is received from the EO Tx.

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