阅读说明：本技术 低信噪比无线电水下通信系统 (Low signal-to-noise ratio radio underwater communication system ) 是由 勒内·施默格罗 拉尔夫·霍夫梅斯特 维贾亚南德·武西利卡拉 瓦莱·卡马洛夫 马蒂亚·康托诺 于 2019-11-19 设计创作，主要内容包括：本申请提供了海底光通信的系统和方法。一种海底光放大器组件可以包括水密壳体和布置在所述壳体内的光子集成电路,所述光子集成电路包括多个光纤输入端和多个光纤输出端,每个光纤输入端被配置成接收第一光缆束的相应光纤的端部,每个光纤输出端对应于相应的光纤输入端以形成光纤输入-输出对,并且被配置成接收第二光缆束的相应光纤的端部。所述光子集成电路包括被光学地耦合到每个相应的光纤输入-输出对的光放大器。所述壳体包括被配置成接收所述第一光缆束的第一水密接入端口和被配置成接收第二光缆束的第二水密接入端口。(The present application provides systems and methods for undersea optical communications. An undersea optical amplifier assembly may include a watertight housing and a photonic integrated circuit disposed within the housing, the photonic integrated circuit including a plurality of optical fiber inputs and a plurality of optical fiber outputs, each optical fiber input configured to receive an end of a respective optical fiber of a first optical cable bundle, each optical fiber output corresponding to a respective optical fiber input to form an optical fiber input-output pair, and configured to receive an end of a respective optical fiber of a second optical cable bundle. The photonic integrated circuit includes an optical amplifier optically coupled to each respective fiber input-output pair. The housing includes a first watertight access port configured to receive the first bundle of optical cables and a second watertight access port configured to receive a second bundle of optical cables.)

1. An undersea optical amplifier assembly comprising:

a watertight housing;

a Photonic Integrated Circuit (PIC) disposed within the housing, the PIC comprising:

a plurality of fiber optic inputs, each fiber optic input configured to receive an end of a respective optical fiber of the first fiber optic cable bundle;

a plurality of fiber output ends, wherein each fiber output end:

corresponding to respective optical fiber input ends to form optical fiber input-output pairs, an

An end configured to receive a respective optical fiber of the second bundle of fiber optic cables; and

an optical amplifier optically coupled to each respective fiber input-output pair, each optical amplifier comprising at least one semiconductor optical amplifier;

a first watertight access port configured to receive the first bundle of optical cables; and

a second watertight access port configured to receive a second bundle of optical cables.

2. The undersea optical amplifier assembly of claim 1 wherein each optical amplifier for each fiber input-output pair comprises a plurality of semiconductor optical amplifiers.

3. The undersea optical amplifier assembly of claim 2 wherein each semiconductor optical amplifier coupled to a given fiber input-output pair is configured to amplify a different frequency band of the optical signal.

4. The undersea optical amplifier assembly of claim 3 wherein the plurality of semiconductor optical amplifiers coupled to a given fiber input-output pair are connected in series with respect to one another.

5. The undersea optical amplifier assembly of claim 3 wherein the plurality of semiconductor optical amplifiers coupled to a given fiber input-output pair are connected to the fiber input-output pair in parallel with each other.

6. The undersea optical amplifier assembly of claim 5 wherein the PIC includes a plurality of optical combiners, each optical combiner configured to combine the outputs of semiconductor optical amplifiers associated with one of the fiber input-output pairs and output the combined optical signals to the fiber outputs of the fiber input-output pairs.

7. The undersea optical amplifier assembly of claim 1 wherein the first watertight access port is further configured to receive a power cable.

8. The undersea optical amplifier assembly of claim 7 further comprising a power converter for converting power received via the power cable to a voltage suitable for powering the PIC.

9. An undersea optical communication link comprising:

a plurality of undersea optical amplifier assemblies connected to each other in series via respective optical cable bundles and respective power cables, wherein each undersea optical amplifier assembly includes at least one photonic integrated circuit in a watertight housing, the photonic integrated circuit including a plurality of optical amplifiers configured to amplify optical signals received at the undersea optical amplifier assembly;

a transmitter disposed at a first end of the communication link, configured to output a plurality of optical signals converted from electrical signals across a plurality of optical fibers of a first optical cable bundle and to output power to a first of the plurality of undersea optical amplifier assemblies;

a receiver configured to receive the plurality of optical signals from a last undersea optical amplifier assembly of the plurality of undersea optical amplifier assemblies and to convert the received optical signals to electrical signals.

10. The undersea optical communication link of claim 9 wherein:

for each optical fiber of the first fiber optic cable bundle, the transmitter includes an interleaver configured to combine a first plurality of component optical signals into one of the plurality of optical signals; and

for each optical fiber of the second optical cable bundle, the receiver includes a deinterleaver configured to separate one of the plurality of optical signals into a second plurality of component optical signals.

11. The undersea optical communication link of claim 9 wherein each watertight housing comprises a single photonic integrated circuit.

12. The undersea optical amplifier link of claim 9 wherein each optical amplifier for each fiber input-output pair comprises a plurality of semiconductor optical amplifiers.

13. The undersea optical amplifier link of claim 12 wherein each semiconductor optical amplifier coupled to a given optical fiber input-output pair is configured to amplify a different frequency band of optical signals.

14. The undersea optical amplifier link of claim 13 wherein the plurality of semiconductor optical amplifiers coupled to a given optical fiber input-output pair are connected in series with respect to one another.

15. The undersea optical amplifier link of claim 13 wherein the plurality of semiconductor optical amplifiers coupled to a given fiber input-output pair are connected to the fiber input-output pair in parallel with each other.

16. The undersea optical amplifier link of claim 15 wherein the photonic integrated circuit includes a plurality of optical combiners, each optical combiner configured to combine the outputs of the semiconductor optical amplifiers associated with one of the fiber input-output pairs and output the combined optical signal to the fiber outputs of the fiber input-output pairs.

17. The undersea optical amplifier link of claim 11 wherein the first watertight access port is further configured to receive a power cable.

18. The undersea optical amplifier link of claim 17 further comprising a power converter for converting power received via the power cable to a voltage suitable for powering the PIC.

19. A method of undersea optical communication, comprising:

receiving, at each of a plurality of optical fiber inputs in a photonic integrated circuit disposed within a watertight housing of an undersea optical amplifier assembly, a plurality of optical signals respectively from a first plurality of optical fibers of a first optical fiber bundle;

amplifying each of the plurality of optical signals by using a plurality of optical amplifiers in the photonic integrated circuit, wherein each optical amplifier comprises at least one semiconductor optical amplifier; and

transmitting the amplified optical signals into a second plurality of optical fibers of a second fiber bundle at each of a plurality of fiber output ends in the photonic integrated circuit, wherein each fiber output end corresponds to a respective fiber input end to form a fiber input-output pair.

20. The method of claim 19, comprising amplifying each of the plurality of optical signals by using a plurality of semiconductor optical amplifiers.

21. The method of claim 20, wherein each of the plurality of semiconductor optical amplifiers for amplifying an optical signal is configured to amplify a different frequency band of the optical signal.

22. The method of claim 21, wherein the plurality of semiconductor optical amplifiers for amplifying the optical signal are connected in series with each other.

23. The method of claim 21, wherein the plurality of semiconductor optical amplifiers for amplifying the optical signal are connected in parallel with each other.

24. The method of claim 23, comprising:

combining outputs of the plurality of semiconductor optical amplifiers for amplifying the optical signal by using a combiner in the photonic integrated circuit; and

the combined optical signal is output to the optical fiber output terminal.

25. The method of claim 19, comprising:

receiving the first bundle of optical fibers via a first watertight access port; and receiving a power cable via the first watertight access port.

26. The method of claim 25, comprising converting power received via the power cable to a voltage suitable for powering the photonic integrated circuit.

27. The method of claim 25, wherein the undersea optical amplifier assembly is one of a plurality of undersea optical amplifier assemblies, the method comprising:

transmitting the plurality of optical signals to the undersea optical amplifier assembly via the first plurality of optical fibers of the first optical fiber bundle using a transmitter disposed at a first end of a communication link;

receiving the plurality of optical signals from a last undersea optical amplifier assembly of the plurality of undersea optical amplifier assemblies by using a receiver disposed at a second end of the communication link; and

the received optical signal is converted into an electrical signal.

28. The method of claim 27, comprising:

for each optical fiber of the first fiber optic bundle, combining a first plurality of component optical signals into one of the plurality of optical signals using an interleaver of the transmitter; and

for each optical fiber of the second fiber optic bundle, separating one of the plurality of optical signals into a second plurality of component optical signals by using a deinterleaver of the receiver.

Background

Today, most intercontinental internet traffic is transmitted via optical underwater systems. Each underwater cable, and particularly very long cables such as transoceanic and transoceanic connections, represents a significant investment on the order of hundreds of millions of dollars. Typically, multiple companies form a community to share the investment and risk of a light underwater system. For today's submarine cables, only very advanced components are used, which results in high costs. This includes components such as repeaters (optical amplifiers), optical transmitters and optical receivers. Recently, so-called Space Division Multiplexing (SDM) has been introduced to increase the achievable capacity through additional fiber pairs in the cable. However, the underlying components and equipment are still costly.

Disclosure of Invention

At least one aspect of the present application relates to an undersea optical amplifier assembly. The amplifier assembly includes a water-tight housing and a Photonic Integrated Circuit (PIC) disposed within the housing. The PIC includes a plurality of fiber optic inputs, each configured to receive an end of a respective optical fiber of a first fiber optic cable bundle. The PIC includes a plurality of fiber outputs. Each fiber output end corresponds to a respective fiber input end to form a fiber input-output pair and is configured to receive an end of a respective fiber of the second fiber optic cable bundle. The PIC includes an optical amplifier optically coupled to each respective fiber input-output pair. Each optical amplifier comprises at least one semiconductor optical amplifier. The amplifier assembly includes a first watertight access port configured to receive a first bundle of optical cables and a second watertight access port configured to receive a second bundle of optical cables.

At least one aspect of the present application relates to an undersea optical communication link that includes a plurality of undersea optical amplifier assemblies connected to one another in series via respective optical fiber bundles and respective power cables. Each undersea optical amplifier assembly includes at least one photonic integrated circuit in a watertight housing, the photonic integrated circuit including a plurality of optical amplifiers configured to amplify optical signals received at the undersea optical amplifier assembly. The link includes a transmitter disposed at a first end of the communication link and configured to output a plurality of optical signals converted from electrical signals across a plurality of optical fibers of a first optical cable bundle and to output power to a first of the plurality of undersea optical amplifier assemblies. The link includes a receiver configured to receive the plurality of optical signals from a last of the plurality of undersea optical amplifier assemblies and convert the received optical signals to electrical signals.

At least one aspect of the present application relates to a method of undersea optical communication. The method includes receiving a plurality of optical signals from a first plurality of optical fibers of a first optical fiber bundle, respectively, at each of a plurality of optical fiber inputs in a photonic integrated circuit disposed within a watertight housing of an undersea optical amplifier assembly. The method includes amplifying each of the plurality of optical signals by using a plurality of optical amplifiers in a photonic integrated circuit. Each optical amplifier comprises at least one semiconductor optical amplifier. The method includes transmitting the amplified optical signals into a second plurality of optical fibers of a second fiber bundle at each of a plurality of fiber output ends in the photonic integrated circuit. Each fiber output end corresponds to a respective fiber input end to form a fiber input-output pair.

According to further aspects, systems and methods of undersea optical communication are provided. An undersea optical amplifier assembly may include a watertight housing and a photonic integrated circuit disposed within the housing. The photonic integrated circuit includes a plurality of fiber inputs and a plurality of fiber outputs, each fiber input configured to receive an end of a respective optical fiber of the first bundle of optical cables. Each fiber output end corresponds to a respective fiber input end to form a fiber input-output pair and is configured to receive an end of a respective fiber of the second fiber optic cable bundle. The photonic integrated circuit includes an optical amplifier optically coupled to each respective fiber input-output pair. The housing includes a first watertight access port configured to receive a first bundle of optical cables and a second watertight access port configured to receive a second bundle of optical cables.

These and other aspects and embodiments are discussed in detail below. The foregoing information and the following detailed description include illustrative examples of various aspects and embodiments, and provide an overview or framework for understanding the nature and character of the claimed aspects and embodiments. The accompanying drawings provide an illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification.

Drawings

The accompanying drawings are not intended to be drawn to scale. Like reference numbers and designations in the various drawings indicate like elements. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

fig. 1 is a block diagram of an undersea optical communication link according to some embodiments;

FIG. 2 is a block diagram of an undersea optical amplifier assembly for an undersea optical communication link according to some embodiments;

FIG. 3A illustrates a block diagram of an amplifier block having a plurality of semiconductor optical amplifiers for serially amplifying respective portions of an optical signal, in accordance with some embodiments;

FIG. 3B is a block diagram of an amplifier block having a plurality of semiconductor optical amplifiers for amplifying respective portions of an optical signal in parallel, according to some embodiments; and

fig. 4 illustrates a flow diagram of an example method of undersea optical communication, according to some embodiments.

Detailed Description

The present disclosure relates generally to systems and methods for long haul undersea optical fiber communications using low cost, compact Semiconductor Optical Amplifiers (SOAs) in repeater stages. In long haul undersea optical fiber communications, a repeater stage is typically provided at discrete points along the optical fiber path to amplify the optical signal, thereby compensating for propagation losses through the long haul optical fiber. Traditionally, high-end optical amplifiers providing high signal-to-noise ratio (SNR) are used in the relay stage, so that the channel capacity (according to shannon capacity law) is maintained throughout the transmission. Some examples of high-end optical amplifiers include fiber amplifiers such as Erbium Doped Fiber Amplifiers (EDFAs). However, electrically operated fiber amplifiers tend to have lower conversion efficiency because power is used to "turn on" a pump light source (typically a bright laser diode), which in turn is used to optically amplify signals traveling along the fiber optic cable. Such optical amplification schemes place limitations on the number and efficiency of fiber amplifiers that can be deployed in an undersea environment, where power limitations are critical both to avoid underwater breakdowns and to reduce the number of bulky, expensive copper wires needed to power the amplifiers over long distances. Furthermore, fiber amplifiers (e.g., EDFAs) employ long lengths of fiber that need to be wound in a generally high form factor package, since the radius of curvature of erbium doped fibers is a minimum of a few centimeters to limit optical losses in the fiber. Consequently, deploying large quantities of EDFAs and similar equipment at long distances in deep sea areas is both expensive and inefficient.

Embodiments disclosed herein provide an exemplary shift in the design and operation of long-range telecommunication systems by using compact, low-cost, and efficient SOAs for repeater stages. SOAs operate at higher power efficiencies than fiber amplifiers, thereby significantly reducing the electrical requirements of undersea lines. Furthermore, SOAs provide wide amplification bandwidths in compact configurations of only a few millimeters or even less. Thus, SOA capability is easily multiplexed over several fibre channels with little impact on the size and power requirements of the repeater stage. The SOA can also amplify optical signals over a wider bandwidth than the EDFA; for example, an SOA can amplify optical signals over a bandwidth of 7-10THz compared to 4THz, which is typical for EDFAs. Furthermore, because of their small size, SOAs exhibit little attenuation outside their amplification bandwidth. Thus, a plurality of SOAs may be combined to amplify a single optical signal in series or in parallel, with each SOA amplifying a single band or portion of a band of the optical signal. Careful design of multiple SOA amplification stages can reduce or eliminate the need for equalizers required for conventional repeaters including EDFAs. Although the SNR of a single SOA channel may be lower than that of a fiber amplifier, the cumulative effects of multi-channel amplification can be corrected at the transmitter level at the output of a long distance cable. Thus, by modifying the transmitter's algorithm to distribute the optical signal channels over more lower SNR SOA channels, the system can achieve a desired Bit Error Rate (BER) despite the lower SNR of each SOA channel, resulting in reduced cost over an entire long-distance deployment.

Fig. 1 is a block diagram of an undersea optical communication link 100 according to some embodiments. The undersea optical communication link 100 includes a transmitter device 110 in communication with a receiver 120 via a plurality of undersea optical amplifier assemblies 130A, 130B, and 130C (collectively "amplifier assemblies 130"). The amplifier assemblies 130 are connected by spans (span)140a, 140b, 140c, and 140d (collectively, "spans 140"). The span 140 and amplifier assembly 130 traverse a body of water 150, such as an ocean, sea, bay, lake, or the like. Typically, the span 140 and amplifier assembly 130 will be on the bottom or floor of the body of water 150, but in some embodiments the span 140 and amplifier assembly 130 may be partially or completely buried below the sea floor, suspended above the bottom, or partially submerged near the surface of the body of water 150. Span 140 may be comprised of a fiber optic bundle having a plurality of optical fibers, where each optical fiber may carry an optical signal or a plurality of component optical signals (e.g., a plurality of optical signal channels). In fig. 1, link 100 is shown to include three amplifier components 130; however, in other embodiments, the link 100 may include a single amplifier component 130 or a plurality of amplifier components 130. The number of amplifier assemblies 130 may depend on the distance that the link 100 must traverse between the transmitter device 110 and the receiver 120 and the optical signal power loss experienced across each span 140. An example amplifier assembly is described in more detail below with reference to fig. 2.

Transmitter device 110 includes components for converting electrical signals to optical signals for communication over link 100. The components may include a laser, a modulator, a digital-to-analog converter, an electrical amplifier, and a coupler for coupling an optical signal into an optical fiber. In some embodiments, the transmitter device 110 may include one or more interleavers for combining multiple component optical signals into a single optical signal for transmission over an optical fiber of a fiber optic bundle. The interleaver is an optical component that can combine groups of optical signal channels into a composite signal stream. The use of an interleaver may increase the channel density of the optical signal. Similarly, the receiver 120 may include one or more deinterleavers for separating the optical signal into a second plurality of optical component signals. Receiver 120 may also include components and circuitry for converting optical signals to electrical signals. The components and circuitry may include photodiodes (or other optical detectors), transimpedance amplifiers, analog-to-digital converters, and additional components such as filters and equalizers for processing signals in the optical and/or electrical domain.

In some implementations, the transmitter device 110 and/or the receiver 120 can include a power supply for providing power to the one or more amplifier components 130. Power may be provided via electrically conductive wires or cables added to the fiber optic bundles of each span 140. In some embodiments, the power may be provided via a conductive wire or cable that is separate and distinct from the span 140. In some implementations, the amplifier component 130 can receive power from a power source that is separate and distinct from the transmitter device 110 and the receiver 120.

Fig. 2 is a block diagram of an undersea optical amplifier assembly 130 for use in an undersea optical communication link according to some embodiments. The amplifier assembly 130 may receive the first fiber optic bundle 210 via a first watertight seal 215. The amplifier assembly 130 may receive the second fiber bundle 220 via a second watertight seal 225. The amplifier assembly 130 includes at least one Photonic Integrated Circuit (PIC) 230. In some embodiments, the amplifier component 130 contains only a single PIC 230. In some embodiments, the amplifier component 130 includes a number of PICs 230. The amplifier assembly 130 is housed in a watertight housing. In some embodiments, the watertight housing may be a universal joint that is not typically used to house a subsea amplifier due to its limited interior space.

The PIC 230 is an integrated silicon component that includes optical, electrical, and/or electro-optical components for routing and amplifying optical signals. In some embodiments, the PIC 230 may comprise a single photonic IC substrate. The PIC 230 has a plurality of Semiconductor Optical Amplifiers (SOAs) 240a, 240b, and 240c (collectively, "SOAs 240"). Each SOA 240 receives an optical signal from an optical fiber 250a, 250b or 250c (collectively "optical fiber 250") via an optical fiber input 260a, 260b or 260c (collectively "optical fiber input 260") and a waveguide 265a, 265b, 265c (collectively "waveguide 265"), respectively. SOA 240 amplifies the optical signal and provides the amplified optical signal to optical fibers 280a, 280b, 280c (collectively referred to as "optical fibers 280") via waveguides 275a, 275b, or 275c (collectively referred to as "waveguides 275") and fiber outputs 270a, 270b, or 270c (collectively referred to as "fiber outputs 270"), respectively. Each fiber 250 and its corresponding fiber 280 form a fiber input-output pair; for example, a first fiber input-output pair consists of fibers 250a and 280a, a second fiber input-output pair consists of fibers 250b and 280b, and so on. In some embodiments, the PIC 230 may include an array of 24 SOAs 240, each SOA 240 providing amplification for a single fiber input-output pair.

In some embodiments, each SOA 240 may include a two-dimensional material based amplifier. In some embodiments, each SOA may include a single conversion stage from electricity to light to improve the overall conversion from electricity to light.

In some embodiments, each SOA 240 shown in fig. 2 may actually be made up of multiple SOAs. The plurality of SOAs of SOA 240 may be arranged in series (as shown in fig. 3A) or in parallel (as shown in fig. 3B). These embodiments are described in more detail below with reference to fig. 3A and 3B.

The fiber input 260 and the fiber output 270 may be couplers adapted to couple optical signals from an optical fiber to or from a waveguide on the PIC 230; such as an edge coupler or a grating coupler.

The amplifier assembly 130 shown in fig. 2 is unidirectional; that is, it amplifies the optical signal from the first bundle 210 and transmits the amplified optical signal to the second bundle 220. However, in some embodiments, the amplifier component 130 may be bi-directional; that is, signals traveling in each direction (along the same fiber or along different fibers) are amplified. Optical circulators may be used to demultiplex optical signals traveling in opposite directions along a single optical fiber. In some embodiments, the PIC 230 may include an SOA 240 for amplifying optical signals traveling in two directions. In some embodiments, the amplifier component 130 may include a plurality of PICs 230, where each PIC 230 has an SOA 240 for amplifying optical signals traveling in one direction.

In some embodiments, the amplifier assembly 130 may include a power converter 290 for receiving power from a conductive wire or cable 295 included in one of the fiber optic bundles 210 or elsewhere. The power converter 290 may convert and/or condition the power provided via the cable 295 and provide the power to the SOA 240 on the PIC. In some embodiments, each amplifier assembly 130 may receive power in a daisy chain fashion, with cables passing through and providing power to multiple amplifier assemblies 130 in succession.

Fig. 3A illustrates a block diagram of an amplifier block 341 having a plurality of semiconductor optical amplifiers 340 for serially amplifying respective portions of an optical signal, in accordance with some embodiments. The amplifier block 341 may be used, for example, as one of the SOAs 240 shown in fig. 2. The amplifier block 341 comprises SOAs 340a, 340b, and 340c (collectively "SOAs 340") arranged in series with respect to one another. The amplifier block 341 may amplify the optical signal received through the first waveguide 365 and transmit the amplified optical signal through the second waveguide 375. In some embodiments, the SOAs 340 may amplify different bands of the optical signal separately such that the overall gain is flat or substantially flat over the bandwidth of the optical signal. Furthermore, a relatively flat gain response over the bandwidth of the optical signal may reduce or eliminate the need for an optical equalizer, thereby conserving optical power and reducing the amount of amplification required (or the number of amplifiers in the link).

Fig. 3B is a block diagram of an amplifier block 342 having a plurality of semiconductor optical amplifiers 340 for amplifying respective portions of an optical signal in parallel, according to some embodiments. The amplifier block 342 may be used as one of the SOAs 240 shown in fig. 2. Amplifier block 341 comprises SOAs 340a, 340b, and 340c (collectively "SOAs 340") in parallel with each other. The amplifier block 342 may amplify the optical signal received through the first waveguide 365 and transmit the amplified optical signal through the second waveguide 375. The amplifier block 342 includes an optical splitter 351 to split the optical signal received from the waveguide 365 and provide a portion of the optical signal to each of the SOAs 340. The amplifier block 342 also includes an optical coupler 352 for recombining the amplified optical signal portions prior to transmission of the amplified optical signal to the waveguide 375.

In some embodiments, in amplifier block 341 or 342, SOA340 may amplify different bands of optical signals, respectively, such that the overall gain is flat or substantially flat over the bandwidth of the optical signals. Furthermore, a relatively flat gain response over the bandwidth of the optical signal may reduce or eliminate the need for an optical equalizer, thereby conserving optical power and reducing the amount of amplification (or number of amplifiers in the link) required. In some embodiments, each SOA may amplify optical bands such as the normal band (C-band), the long band (L-band), the short band (S-band), the 0-band, and so on. In some embodiments, each SOA may amplify a portion of the optical transmission band.

Fig. 4 illustrates a flow diagram of an example method 400 of undersea optical communication, in accordance with some embodiments. The method 400 may be performed by an amplifier assembly, such as the amplifier assembly 130 described previously, and/or an undersea optical communication system, such as the optical communication link 100 described previously. Method 400 optionally includes combining the plurality of component optical signals by using an interleaver (stage 410). Method 400 optionally includes transmitting the plurality of optical signals via an optical fiber (stage 420). Method 400 includes receiving a plurality of optical signals at a photonic integrated circuit of an undersea optical amplifier assembly (stage 430). Method 400 includes amplifying each optical signal by using a Semiconductor Optical Amplifier (SOA) (stage 440). Method 400 includes transmitting the plurality of amplified optical signals into a second optical fiber (stage 450). Method 400 optionally includes receiving the plurality of amplified optical signals at a receiver (stage 460). Method 400 optionally includes separating each amplified optical signal into a plurality of component optical signals by using a deinterleaver (stage 470).

In some embodiments, method 400 may optionally include combining multiple component optical signals by using an interleaver (stage 410). The combining may be performed using an interleaver of a transmitter, such as the transmitter device 110 described previously. The interleaver may take a pair (or more) of optical signals and combine them into a single optical signal. In some embodiments, the transmitter may include a plurality of interleavers, each interleaver for generating and transmitting each optical signal along a fiber bundle to the undersea optical amplifier assembly.

In some embodiments, method 400 may optionally include transmitting a plurality of optical signals via an optical fiber (stage 420). The transmitter may be disposed at a first end of the communication link and configured to transmit each of the plurality of optical signals along the fiber bundle to a first one of the one or more undersea optical amplifier assemblies.

Method 400 includes receiving a plurality of optical signals at a photonic integrated circuit of an undersea optical amplifier assembly (stage 430). An undersea optical amplifier assembly, such as the previously described amplifier assembly 130, may receive a plurality of optical signals transmitted by the transmitter. The amplifier assembly includes at least one Photonic Integrated Circuit (PIC) having a plurality of fiber inputs, such as the PIC 230 described previously. The PIC may be housed within a watertight housing of the amplifier assembly, the housing having a watertight seal for receiving the fiber optic bundle. Each fiber input may receive an optical fiber from the bundle and couple an optical signal into the PIC. In some embodiments, method 400 may additionally include receiving power via a wire or cable that is received via a watertight seal. In some implementations, the method 400 may include converting and/or conditioning the received power into a form usable by components on the PIC.

Method 400 includes amplifying each optical signal using a Semiconductor Optical Amplifier (SOA) (stage 440). The PIC includes a plurality of SOAs configured to amplify the optical signal. In some embodiments, the PIC includes a plurality of SOA blocks, wherein each SOA block amplifies an optical signal for a single fiber input-output pair. Each SOA block may include a plurality of SOAs. The SOAs may be arranged in series or in parallel, with each SOA in a block of SOAs amplifying a different wavelength band of the optical signal such that the SOAs provide amplification that is flat or substantially flat over the entire bandwidth of the optical signal. In embodiments where the SOAs in the SOA block are arranged in parallel, the SOA block may include an optical splitter for splitting the optical signal and transmitting a portion thereof to each SOA, and an optical combiner for combining the amplified portions of the optical signal. Each SOA or SOA block may output an amplified optical signal to the fiber output of the PIC.

Method 400 includes transmitting the plurality of amplified optical signals into a second optical fiber (stage 450). The amplifier assembly may route each amplified optical signal from its fiber output on the PIC to a second plurality of optical fibers and into a second bundle of optical fibers. Each fiber output end corresponds to a respective fiber input end to form a fiber input-output pair.

In some embodiments, the receiving, amplifying and transmitting stages 430-450 may be repeated at one or more or many additional amplifier assemblies of the undersea optical communication link.

In some embodiments, method 400 may optionally include receiving a plurality of amplified optical signals at a receiver (stage 460). A receiver, such as the previously described receiver 120, may be disposed at the second end of the communication link and configured to receive the plurality of amplified optical signals from the last of the amplifier assembly or assemblies. The receiver may convert the received optical signal into an electrical signal by using the receiver.

In some embodiments, method 400 may optionally include separating each amplified optical signal into a plurality of component optical signals by using a deinterleaver (stage 470). In embodiments where the transmitter interleaves the plurality of component optical signals to generate each optical signal, the receiver may comprise a complementary deinterleaver for separating each amplified optical signal into a second plurality of component optical signals. The receiver may convert each of the second plurality of component optical signals to one or more electrical signals.

In some embodiments, method 400 may include more or fewer stages or steps without departing from the scope of the present disclosure.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

References to "or" may be construed as inclusive such that any term described using "or" may refer to any single, more than one, and all of the described terms. The labels "first", "second", "third", etc. do not necessarily indicate an order and are generally only used to distinguish between similar or analogous items or elements.

Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the embodiments shown herein but are to be accorded the widest scope consistent with the present disclosure, the principles and novel features disclosed herein.