Amplification of non-polarized light signals using polarization dependent gain optical amplifiers

Abstract

A light amplification circuit, a light amplification method, and a light circuit for amplifying a non-polarized light signal are provided. The optical amplification circuit may include an input interface, a pair of optical amplifiers having polarization dependent gain (PDG) curves, and an output interface. The input interface receives a non-polarized light signal. The input interface outputs a first polarization component and a second polarization component according to a received non-polarized light signal. A pair of optical amplifiers may amplify the first polarization component and the second polarization component according to a PDG curve. The output interface may output an amplified version of the non-polarized light signal based on the amplified first polarized component and the amplified second polarized component.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to provisional patent application "High Power Low Polarization Dependent Gain Semiconductor Optical Amplifier" (Application No. 63 / 589,750) filed in the United States Patent and Trademark Office on October 12, 2023, and is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to optical communication systems. More specifically, the present disclosure relates to using a polarization dependent gain optical amplifier to amplify unpolarized optical signals in an optical communication system. Background Art

[0004] An optical communication system is a system that uses optical signals to exchange data over long distances. Typically, an optical communication system may include one or more optical amplifiers to compensate for power losses that occur during signal transmission. These optical amplifiers receive optical signals and output an amplified version of the received optical signal. The input optical signal is usually unpolarized and contains multiple polarization states. Therefore, the optical amplifier used should be polarization-independent in order to effectively amplify the unpolarized optical signal.

[0005] Commonly used erbium-doped fiber amplifiers (EDFAs) can operate as polarization-independent optical amplifiers using various techniques such as polarization scrambling or polarization-maintaining components. Such EDFAs may include erbium-doped fibers and pump laser sources. The pump laser source can inject an input optical signal into the erbium-doped fiber to achieve amplification of the input optical signal. However, the combination of erbium-doped fiber and pump laser source may make EDFA bulky, limiting its application in compact optical communication systems. In addition, EDFAs are usually limited to the C-band range, further limiting their application in optical communication systems that operate only in this band.

[0006] Therefore, a technical solution that can overcome the above problems is needed.By comparing the system with certain aspects of the present disclosure, those skilled in the art will find the limitations and shortcomings of the traditional method, as described in the rest of this application and with reference to the drawings. Summary of the invention

[0007] Various embodiments of the present disclosure are provided herein for amplifying non-polarized optical signals in optical communication systems. In one aspect of the present disclosure, an optical amplifier circuit for amplifying non-polarized optical signals is provided. The optical amplifier circuit includes an input interface, a pair of optical amplifiers coupled to the input interface, and an output interface coupled to the pair of optical amplifiers. The input interface is configured to receive a non-polarized optical signal and output a first polarization component and a second polarization component according to the non-polarized optical signal. The pair of optical amplifiers has a polarization dependent gain (PDG) curve. The pair of optical amplifiers is configured to amplify the first polarization component and the second polarization component according to the PDG curve. The output interface is configured to output an amplified version of the non-polarized optical signal according to the amplified first polarization component and the amplified second polarization component.

[0008] In some embodiments, the input interface includes a polarization splitter configured to separate the unpolarized optical signal into a first polarization component and a third polarization component, wherein the third polarization component is orthogonal to the first polarization component. The input interface also includes a polarization converter configured to convert the third polarization component into a second polarization component.

[0009] In some embodiments, each of the first polarization component and the second polarization component corresponds to a transverse electric (TE) mode component. The third polarization component corresponds to a transverse magnetic (TM) mode component.

[0010] In some embodiments, each of the PDG curves indicates that the optical gain of each optical amplifier in the pair of optical amplifiers is dominated by the TE mode component.

[0011] In some embodiments, the pair of optical amplifiers includes a first optical amplifier and a second optical amplifier. The input interface further includes an optical mirror. The polarization splitter is further configured to allow the third polarization component to pass toward the polarization converter and reflect the first polarization component toward the optical mirror. The polarization converter is further configured to output the second polarization component to the first optical amplifier according to the conversion of the third polarization component. The optical mirror is configured to direct the first polarization component to the second optical amplifier.

[0012] In some embodiments, each of the first polarization component and the second polarization component corresponds to a TM mode component. The third polarization component corresponds to a TE mode component.

[0013] In some embodiments, the pair of optical amplifiers includes a first optical amplifier and a second optical amplifier. The input interface further includes an optical mirror. The polarization splitter is configured to allow the first polarization component to pass through the polarization splitter to reach the first optical amplifier, and reflect the third polarization component toward the optical mirror. The optical mirror is configured to guide the third polarization component to the polarization converter. The polarization converter is configured to output the second polarization component to the second optical amplifier according to the conversion of the third polarization component.

[0014] In some embodiments, the first polarization component corresponds to a TM mode component and the second polarization component corresponds to a TE mode component.

[0015] In some embodiments, the pair of optical amplifiers includes a first optical amplifier and a second optical amplifier. The input interface includes a polarization splitter and an optical mirror. The polarization splitter is configured to split the unpolarized optical signal into a first polarization component and a second polarization component. In addition, the polarization splitter is configured to allow the first polarization component to pass through the polarization splitter to reach the first optical amplifier, and reflect the second polarization component to the optical mirror. The optical mirror is configured to direct the second polarization component to the second optical amplifier.

[0016] In some embodiments, the PDG curve includes a first PDG curve associated with the first optical amplifier and a second PDG curve associated with the second optical amplifier. The first PDG curve indicates that the optical gain of the first optical amplifier dominates the TM mode component. The second PDG curve indicates that the optical gain of the second optical amplifier dominates the TE mode component.

[0017] In some embodiments, the output interface includes an optical mirror and a polarization combiner. The optical mirror is configured to direct the amplified first polarization component to the polarization combiner. The polarization combiner is configured to combine the amplified first polarization component and the amplified second polarization component. In addition, the polarization combiner is configured to output an amplified version of the unpolarized light signal based on the combination of the amplified first polarization component and the amplified second polarization component.

[0018] In some embodiments, the pair of optical amplifiers includes a first optical amplifier and a second optical amplifier. The output interface further includes a polarization converter. The polarization converter is located between the first optical amplifier and the optical mirror or between the second optical amplifier and the polarization combiner.

[0019] In some embodiments, the pair of optical amplifiers comprises a pair of semiconductor optical amplifiers (SOAs).

[0020] In some embodiments, the optical amplification circuit further comprises an amplification control circuit configured to generate a driving current for each SOA of the pair of SOAs and control amplification of each SOA of the pair of SOAs according to the generated driving current.

[0021] On the other hand, an optical path for amplifying non-polarized optical signals is provided. The optical path includes an optical splitter, a plurality of optical amplification circuits coupled to the optical splitter, and an optical combiner coupled to the plurality of optical amplification circuits. The optical splitter is configured to receive a non-polarized input optical signal having a set of characteristics. The optical splitter is further configured to branch the non-polarized input optical signal into a plurality of non-polarized optical signals according to the set of characteristics. Each of the plurality of optical amplification circuits includes a pair of optical amplifiers having a PDG curve. Each of the plurality of optical amplification circuits is configured to receive a respective non-polarized optical signal among the plurality of non-polarized optical signals. In addition, each of the plurality of optical amplification circuits is configured to amplify a respective non-polarized optical signal according to the PDG curve, and output a respective amplified non-polarized optical signal among the plurality of amplified non-polarized optical signals. The optical combiner is configured to receive a plurality of amplified non-polarized optical signals. In addition, the optical combiner is configured to combine a plurality of amplified non-polarized optical signals, and output an amplified version of the non-polarized input optical signal according to the combination of the plurality of amplified non-polarized optical signals.

[0022] In some embodiments, the set of characteristics corresponds to at least one of a plurality of wavelength bands of the unpolarized input optical signal or a power level of the unpolarized input optical signal.

[0023] In some embodiments, each of the plurality of unpolarized optical signals has a specific wavelength band among the multiple wavelength bands of the unpolarized input optical signal.

[0024] In some embodiments, each of the plurality of unpolarized optical signals has a specific power ratio relative to a power level of the unpolarized input optical signal.

[0025] In another aspect, an optical communication method for amplifying a non-polarized optical signal is provided. The optical communication method is implemented by an optical amplification circuit including a pair of optical amplifiers, wherein the pair of optical amplifiers has a PDG curve. The optical communication method includes receiving a non-polarized optical signal and obtaining a first polarization component and a second polarization component based on the non-polarized optical signal. In addition, the optical communication method also includes amplifying the first polarization component and the second polarization component according to the PDG curve. In addition, the optical communication method also includes outputting an amplified version of the non-polarized optical signal based on the amplified first polarization component and the amplified second polarization component.

[0026] Some embodiments are based on the recognition that an optical amplifier should be polarization-independent in order to effectively amplify non-polarized optical signals. To this end, some embodiments of the present disclosure provide an optical amplifier circuit using a pair of optical amplifiers having a PDG curve. Using this pair of optical amplifiers can enable the optical amplifier circuit to be used as a polarization-independent amplifier circuit (or a low polarization-dependent amplifier circuit). As described herein, a polarization-independent amplifier circuit can correspond to an optical amplifier circuit that can amplify an input non-polarized optical signal without distinguishing its TE and TM mode components. In further embodiments, an optical circuit using multiple optical amplifier circuits can be provided. Using these optical amplifier circuits, each optical amplifier circuit can be customized to a different wavelength band, which in turn enables the optical circuit to be used in an optical communication system operating in a wide wavelength band.

[0027] Other purposes, advantages, novel features and further applicable scopes of the present disclosure will be partially described in the detailed description below, and those skilled in the art will understand some of the contents after reading the following, or can understand some of the contents through the practice of the present disclosure. Although the above description contains many specific details, these details should not be understood as limiting the scope of the present disclosure, but are merely some of the currently preferred embodiments of the present disclosure. Therefore, there may be other various embodiments within its scope. Therefore, the scope of the present disclosure should not be determined by the described embodiments, but by the attached claims and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various embodiments of the present disclosure are illustrated by way of example and not limitation in the accompanying drawings, in which like reference numerals designate similar parts and in which:

[0029] Figure 1 is a schematic diagram showing a photonic device according to various embodiments of the present disclosure;

[0030] Figure 2 is a schematic diagram showing an optical amplification circuit according to various embodiments of the present disclosure;

[0031] Figure 3 is a schematic diagram showing another optical amplification circuit according to various embodiments of the present disclosure;

[0032] Figure 4 is a schematic diagram showing yet another optical amplification circuit according to various embodiments of the present disclosure;

[0033] Figure 5 is a schematic diagram showing an optical circuit according to various embodiments of the present disclosure; and

[0034] Figure 6 is a flow chart illustrating a method of light amplification according to various embodiments of the present disclosure. DETAILED DESCRIPTION

[0035] The present disclosure may be better understood with reference to the detailed drawings and descriptions herein. Various embodiments will be discussed below with reference to the drawings. However, it will be readily appreciated by those skilled in the art that the detailed descriptions given herein with respect to the drawings are only for the purpose of explanation, as the methods and systems may be extended beyond the described embodiments. In one example, the teachings presented and the needs of a particular application may produce a variety of alternative and suitable methods to implement the functions of any detail described herein. Therefore, any method may be selected beyond the specific implementation in the embodiments described and shown below.

[0036] References such as "one embodiment", "another embodiment", "yet another embodiment", "one example", "another example", "yet another example", "for example", etc. indicate that the described embodiment or example may include certain features, structures, characteristics, attributes, elements, or limitations, but not every embodiment or example necessarily includes the certain features, structures, characteristics, attributes, elements, or limitations. In addition, repeated use of the phrase "in one embodiment" does not necessarily refer to the same embodiment.

[0037] Reference Figure 1 , FIG. 100 shows a photonic device 102 according to various embodiments of the present disclosure. In various embodiments, the photonic device 102 may include an optical integrated circuit (IC) 104, a first waveguide 106, a second waveguide 108, and a control circuit 110. In addition, the photonic device 102 may include an optical signal generating circuit 112 and / or an optical signal receiving circuit 114. As described herein, the optical signal generating circuit 112 may be a circuit (or device) that converts an electrical signal into an optical signal for various applications such as optical communication and data processing. In one example, the optical signal generating circuit 112 may include one or more light sources and a driving circuit. The driving circuit may generate and provide a driving signal to the light source to drive (or control) the light source. The light source may convert the electrical signal into an optical signal according to the driving signal. For example, the light source may include a laser diode (LD), a light emitting diode (LED), a vertical cavity surface emitting laser (VCSEL), and the like.

[0038] As used herein, the optical signal receiving circuit 114 may be a circuit (or device) that converts an optical signal into an electrical signal for further processing or analysis. In one example, the optical signal receiving circuit 114 may include at least one photodetector and at least one application processor. The photodetector may convert an optical signal into an electrical signal. For example, the photodetector may include a PIN photodiode, an avalanche photodiode, a phototransistor, a quantum dot photodetector, a charge coupled device (CCD), etc. The application processor may perform various applications related thereto according to the electrical signal. Although the optical signal generating circuit 112 and / or the optical signal receiving circuit 114 are shown as being in the photonic device 102, the scope of the present disclosure is not limited thereto. In some example embodiments, the optical signal generating circuit 112 and / or the optical signal receiving circuit 114 may be located outside the photonic device 102 without departing from the scope of the present disclosure.

[0039] In many embodiments, the first waveguide 106 and the second waveguide 108 may be coupled to the optical signal generating circuit 112 and the optical signal receiving circuit 114, respectively. In addition, the first waveguide 106 and the second waveguide 108 may be coupled to the optical IC 104. For example, the first waveguide 106 may include a first end coupled to the optical signal generating circuit 112 and a second end coupled to the optical IC 104. Similarly, the second waveguide 108 may include a first end coupled to the optical signal receiving circuit 114 and a second end coupled to the optical IC 104.

[0040] In other embodiments, the first waveguide 106 may be configured to receive the first optical signal 116 from the optical signal generating circuit 112. In addition, the first waveguide 106 may be configured to output the first optical signal 116 to the optical IC 104. The second waveguide 108 may be configured to receive the second optical signal 118 from the optical IC 104. In addition, the second waveguide 108 may be configured to output the second optical signal 118 to the optical signal receiving circuit 114. In one example, the second optical signal 118 may be an amplified version of the first optical signal 116. As used herein, the first waveguide 106 and the second waveguide 108 may correspond to an optical fiber, a planar waveguide, or a similar device. For example, the first waveguide 106 and the second waveguide 108 may be configured to allow the first optical signal 116 and the second optical signal 118 to pass through, respectively. In one example, each of the first waveguide 106 and the second waveguide 108 may include a single-mode optical fiber (SMF), a multi-mode optical fiber (MMF), etc. Although the first waveguide 106 and the second waveguide 108 are shown as being directly coupled to the optical IC 104, the scope of the present disclosure is not limited thereto. In some example embodiments, the first waveguide 106 and the second waveguide 108 may be coupled to the optical IC 104 through first and second lenses, respectively, without departing from the scope of the present disclosure. For example, the first and second lenses may correspond to microlenses, gradient refractive index (GRIN) lenses, or similar lenses.

[0041] In many embodiments, the control circuit 110 can be coupled to the optical IC 104. The control circuit 110 can be configured to generate a drive current 120 and inject it into the optical IC 104. The injected drive current 120 can cause the optical IC 104 to output a second optical signal 118 based on the first optical signal 116. In one example, the drive current 120 can be a bias current, a modulation signal, or the like. Although the control circuit 110 is shown as being implemented in the photonic device 102, the scope of the present disclosure is not limited thereto. In some example embodiments, the control circuit 110 can be located outside the photonic device 102 without departing from the scope of the present disclosure.

[0042] In further embodiments, the optical IC 104 may be coupled to each of the first waveguide 106, the second waveguide 108, and / or the control circuit 110. The optical IC 104 may be configured to receive a first optical signal 116 from the first waveguide 106. In one embodiment, the optical IC 104 may include one or more input ports and one or more output ports. The first optical signal 116 may be received through one input port of the plurality of input ports. In addition, the optical IC 104 may be configured to output a second optical signal 118 to the second waveguide 108. In one example, the second optical signal 118 may be output through one output port of the plurality of output ports. In various embodiments, in order to output the second optical signal 118, the optical IC 104 may be configured to amplify the first optical signal 116 according to a drive current 120 provided by the control circuit 110. The second optical signal 118 may correspond to an amplified version of the first optical signal 116. The optical IC 104 may correspond to a gain chip, a tunable laser, and the like.

[0043] Certain embodiments are based on the recognition that the first optical signal 116 received by the optical IC 104 may correspond to an unpolarized optical signal. For example, the optical signal generation circuit 112 may generate and output an unpolarized optical signal as the first optical signal 116. Alternatively, the first optical signal 116 may become an unpolarized optical signal after propagating through the first waveguide 106. As used herein, an unpolarized optical signal may correspond to an optical signal that includes a time-varying mixture of polarization mode components (e.g., a transverse electric (TE) mode component and a transverse magnetic (TM) mode component) without one polarization mode component being dominant over another polarization mode component.

[0044] Some embodiments are based on the recognition that the optical IC 104 should be polarization-independent in order to effectively amplify unpolarized optical signals. To this end, the optical IC 104 may be equipped with an optical amplifier circuit 122. In various embodiments, the optical amplifier circuit 122 may include a plurality of polarization-dependent gain optical amplifiers, which together enable the optical amplifier circuit 122 to function as a polarization-independent amplifier circuit (or a low polarization-dependent amplifier circuit). As described herein, the polarization-independent amplifier circuit may correspond to an optical amplifier circuit that can amplify an input unpolarized optical signal without distinguishing between TE and TM mode components. The optical amplifier circuit 122 will be combined with Figures 2 to 5 Provide detailed explanation.

[0045] See also Figure 2 , Figure 2 An optical amplification circuit 202 is shown according to some example embodiments of the present disclosure. Figure 2 Will combine Figure 1 The optical amplifier circuit 202 may correspond to Figure 1 The optical amplifier circuit 122 shown in FIG. Figure 2 In the illustrated embodiment, the optical amplifier circuit 202 may include an input interface 204, a pair of optical amplifiers 206A and 206B, and an output interface 208. In various embodiments, the input interface 204 may be configured to receive an unpolarized optical signal 210. In one embodiment, the optical amplifier circuit 202 may include at least one input port and at least one output port. In an example embodiment, the input port may be coupled to an optical fiber to allow the unpolarized optical signal 210 to pass through. In this example embodiment, the input interface 204 may receive the unpolarized optical signal 210 through the input port. In one example, the received unpolarized optical signal 210 may include a mixture of TE and TM mode components. In some embodiments, the input interface 204 may be further configured to output a first polarization component 212 and a second polarization component 216 based on the unpolarized optical signal 210. In order to output the first polarization component 212 and the second polarization component 216, the input interface 204 may include a polarization splitter 204A, an optical mirror 204B, and a polarization converter 204C.

[0046] In many embodiments, the polarization splitter 204A can be disposed within the input interface 204 (or the optical amplifier circuit 202) so that the polarization splitter 204A faces the input port of the optical amplifier circuit 202. The polarization splitter 204A can be configured to split the unpolarized optical signal 210 into a first polarization component 212 and a third polarization component 214. The third polarization component 214 can be orthogonal to the first polarization component 212. For example, the first polarization component 212 and the third polarization component 214 can correspond to the TE and TM mode components of the unpolarized optical signal 210, respectively. In one embodiment, the polarization splitter 204A can correspond to a polarization splitter (e.g., a cube polarization splitter, a flat plate polarization splitter, or a similar device). The polarization splitter 204A can be further configured to allow the third polarization component 214 corresponding to the TM mode component to pass through the polarization splitter 204A and move toward the polarization converter 204C. In addition, the polarization splitter 204A can also be configured to reflect the first polarization component 212 corresponding to the TE mode component toward the optical mirror 204B.

[0047] In many embodiments, the polarization converter 204C can be disposed adjacent to the polarization splitter 204A so that the polarization converter 204C receives the third polarization component 214. The polarization converter 204C can be configured to convert the third polarization component 214 into a second polarization component 216. For example, the polarization converter 204C can rotate the polarization plane of the third polarization component 214 and output the polarization component after the polarization plane is rotated as the second polarization component 216. In one example, the polarization converter 204C can rotate the polarization plane of the third polarization component 214 so that the second polarization component 216 is orthogonal to the third polarization component 214. For example, if the third polarization component 214 corresponds to a TM mode component, the second polarization component 216 can correspond to a TE mode component. In one embodiment, the polarization converter 204C can correspond to a wave plate, a Faraday rotator, or a similar device. In one example, the wave plate can correspond to a half-wave plate, a combination of two quarter-wave plates, or a similar device. Polarization converter 204C may be further configured to direct second polarization component 216 toward first optical amplifier 206A of a pair of optical amplifiers 206A and 206B.

[0048] In a further embodiment, the optical mirror 204B may be positioned below the polarization splitter 204A so that the optical mirror 204B receives the first polarization component 212 reflected by the polarization splitter 204A. The optical mirror 204B may be configured to direct the first polarization component 212 to the second optical amplifier 206B in the pair of optical amplifiers 206A and 206B. For example, the optical mirror 204B may reflect the received first polarization component 212 by 90° so as to direct the first polarization component 212 to the second optical amplifier 206B. In one embodiment, the optical mirror 204B may correspond to a right angle prism, a mirror assembly having a single plane mirror positioned at a 45° angle to the first polarization component 212, or the like.

[0049] In further embodiments, the pair of optical amplifiers 206A and 206B may be coupled to the input interface 204. For example, the pair of optical amplifiers 206A and 206B may be coupled to the input interface 204 via an optical fiber, a numerical aperture (NA) matching optical lens, etc. The pair of optical amplifiers 206A and 206B may be disposed between the input interface 204 and the output interface 208. Specifically, the first optical amplifier 206A may be positioned such that the first optical amplifier 206A faces the polarization converter 204C for receiving the second polarization component 216. Similarly, the second optical amplifier 206B may be positioned to face the optical mirror 204B for receiving the first polarization component 212. The first optical amplifier 206A and the second optical amplifier 206B may be configured to amplify the second polarization component 216 and the first polarization component 212, respectively. For example, to amplify the second polarization component 216, the first optical amplifier 206A may increase the optical signal strength and / or power level of the second polarization component 216. Likewise, to amplify the first polarization component 212 , the second optical amplifier 206B may increase the optical signal strength and / or power level of the first polarization component 212 .

[0050] In further embodiments, the pair of optical amplifiers 206A and 206B may correspond to a pair of semiconductor optical amplifiers (SOAs). Hereinafter, the pair of optical amplifiers 206A and 206B may be referred to as a pair of SOAs 206A and 206B. In various embodiments, the optical amplification circuit 202 may further include (or may be further coupled to) at least one amplification control circuit. In one example, the amplification control circuit may correspond to Figure 1. In one embodiment, the amplification control circuit may be configured to control the amplification of each SOA in the pair of SOAs 206A and 206B to obtain a specific optical gain from each SOA in the pair of SOAs 206A and 206B. For example, the amplification control circuit may control the amplification of each SOA in the pair of SOAs 206A and 206B to increase the optical signal intensity (or power level) of the first polarization component 212 and the second polarization component 216 to a specific optical signal intensity (or a specific power level). To control the amplification, the amplification control circuit may generate a drive current for each SOA in the pair of SOAs 206A and 206B and inject the generated drive current into each SOA in the pair of SOAs 206A and 206B. For example, the generated drive current may correspond to a bias current, a modulation signal, or the like.

[0051] In further embodiments, each SOA of a pair of SOAs 206A and 206B may include an optical gain waveguide having a plurality of quantum well structures. In further embodiments, by designing the quantum well structure, the optical gain of each SOA of a pair of SOAs 206A and 206B may be customized for one of the TE or TM mode components of a given drive current. For example, by changing the number of quantum well structures, the size of the quantum well structures, and / or the strain design of the quantum well structures, the optical gain of each SOA in a pair of SOAs 206A and 206B may be customized for one of the TE or TM mode components. Therefore, in these embodiments, a pair of SOAs 206A and 206B may correspond to a pair of polarization dependent gain (PDG) optical amplifiers having PDG curves. For example, each PDG curve of the PDG curves may include the PDG of each SOA in a pair of SOAs 206A and 206B for a given drive current. In one example, the PDG of a particular SOA (e.g., SOA 206A or 206B) may correspond to the optical gain ratio of the TE and TM mode components obtained by the particular SOA. The PDG of a particular SOA can indicate whether the optical gain of the particular SOA is dominated by the TE mode component or the TM mode component. Figure 2 In the illustrated embodiment, the optical gain of the pair of SOAs 206A and 206B can be tailored for the TE mode component. Therefore, the PDG curve of the pair of SOAs 206A and 206B can show that the optical gain of the pair of SOAs 206A and 206B is dominated by the TE mode component.

[0052] In various embodiments, the optical gain waveguide included in each SOA of the pair of SOAs 206A and 206B may include a waveguide input port and a waveguide output port. In some embodiments, the first SOA 206A may receive a second polarization component 216 corresponding to a TE mode component through the waveguide input port. In addition, the first SOA 206A may amplify the second polarization component 216 according to the PDG curve of the first SOA 206A. In addition, the first SOA 206A may output the amplified second polarization component 218 through the waveguide output port according to the amplification result. Similarly, the second SOA 206B may output the amplified first polarization component 220 by amplifying the first polarization component 212 using the PDG curve of the second SOA 206B. In some embodiments, the optical surfaces of the waveguide input port and the output port may be coated with an anti-reflection (AR) optical film to suppress back reflection, light reflection, or the like.

[0053] In various embodiments, the output interface 208 can be coupled to a pair of SOAs 206A and 206B. For example, the output interface 208 can be coupled to the pair of SOAs 206A and 206B using optical fibers. The output interface 208 can be configured to output a non-polarized optical signal 224 based on the amplified first polarization component 220 and the amplified second polarization component 218. For example, the non-polarized optical signal 224 can correspond to an amplified version of the non-polarized optical signal 210. To output the non-polarized optical signal 224, the output interface 208 can include a polarization combiner 208A, an optical mirror 208B, and a polarization converter 208C.

[0054] In several embodiments, the optical mirror 208B may be positioned within the output interface 208 (or the optical amplification circuit 202) such that the optical mirror 208B faces the first SOA 206A to receive the amplified second polarization component 218. The optical mirror 208B may be configured to direct the amplified second polarization component 218 toward the polarization combiner 208A. For example, the optical mirror 208B may reflect the amplified second polarization component 218 by 90° so as to direct the amplified second polarization component 218 toward the polarization combiner 208A. In one embodiment, the optical mirror 208B may correspond to a right angle prism, a reflector assembly, and the like.

[0055] In many embodiments, the polarization converter 208C can be positioned within the output interface 208 (or the optical amplification circuit 202) so that the polarization converter 208C faces the second SOA 206B to receive the amplified first polarization component 220. The polarization converter 208C can be configured to convert the amplified first polarization component 220 into an amplified third polarization component 222. In one example, the amplified third polarization component 222 can be orthogonal to the amplified first polarization component 220. For example, if the amplified first polarization component 220 corresponds to a TE mode component, the amplified third polarization component 222 can correspond to a TM mode component. In one embodiment, the polarization converter 208C can correspond to a wave plate, a Faraday rotator, or a similar device. The polarization converter 208C can be further configured to direct the amplified third polarization component 222 to the polarization combiner 208A.

[0056] In many embodiments, the polarization combiner 208A can be positioned below the optical mirror 208B and adjacent to the polarization converter 208C, so that the polarization combiner 208A receives the amplified second polarization component 218 and the amplified third polarization component 222. In one embodiment, the polarization combiner 208A can be a polarization beam combiner configured to combine the amplified second polarization component 218 corresponding to the TE mode component with the amplified third polarization component 222 corresponding to the TM mode component. In addition, the polarization combiner 208A can output a non-polarized optical signal 224 based on the combination of the amplified second polarization component 218 and the amplified third polarization component 222. In one example, the polarization combiner 208A can output the non-polarized optical signal 224 through the output port of the optical amplification circuit 202. For example, the non-polarized optical signal 224 can correspond to an amplified version of the non-polarized optical signal 210.

[0057] Thus, the pair of SOAs 206A and 206B and the input interface 204 and the output interface 208 enable the optical amplifier circuit 202 to function as a polarization-independent amplifier circuit to amplify the non-polarized optical signal 210. Since the optical amplifier circuit 202 does not use bulky optical devices (such as pump laser sources used in conventional devices), the optical amplifier circuit 202 can be very small and its use in compact optical communication systems will not be limited. For example, the optical amplifier circuit 202 can be used in optical communication systems such as continuous wave drive systems and power modulation drive systems. In addition, by using a pair of SOAs 206A and 206B, the optical amplifier circuit 202 can independently control the optical gain of the TE and TM mode components by independently tuning the drive currents of the pair of SOAs 206A and 206B. This independent control of the optical gain enables the optical amplifier circuit 202 to encode the input optical signal (e.g., the non-polarized optical signal 210) according to its TE and TM mode components. Therefore, the optical amplifier circuit 202 can be used in various secure optical communication systems.

[0058] Some embodiments are based on the recognition that the use of optical mirrors 204B and 208B and polarization converters 204C and 208C may result in light loss. Figure 2 In the illustrated embodiment, the TE and TM mode components input to the pair of SOAs 206A and 206B are interchanged at the output of the optical amplifier circuit 202 to provide symmetrical optical losses. For example, to interchange the TE and TM mode components, the optical mirror 208B and the polarization converter 208C may be disposed diagonally relative to the optical mirror 204B and the polarization converter 204C, respectively, within the output interface 208. In some embodiments, the symmetrical optical losses may be compensated by adjusting the optical gains of the pair of SOAs 206A and 206B.

[0059] Although the polarization converter 208C is shown to be located between the second SOA 206B and the polarization combiner 208A, the scope of the present disclosure is not limited thereto. In some example embodiments, the polarization converter 208C may be disposed between the first SOA 206A and the optical mirror 208B. In these embodiments, the optical loss may be compensated by independently adjusting the optical gain of a pair of SOAs 206A and 206B.

[0060] Although the figure shows that the polarization converter 204C is located between the polarization splitter 204A and the first SOA 206A, the scope of the present disclosure is not limited to this. In some more embodiments, if the PDG curves of a pair of SOAs 206A and 206B indicate that the optical gain of a pair of SOAs 206A and 206B is dominated by the TM mode component, the polarization converter 204C can be disposed between the optical mirror 204B and the second SOA 206B. Alternatively, if the polarization splitter 204A allows the first polarization component 212 corresponding to the TE mode component to pass toward the first SOA 206A and reflects the third polarization component 214 corresponding to the TM mode component, the polarization converter 204C can be disposed between the optical mirror 204B and the second SOA 206B. The optical amplifier circuit 202 has the polarization converter 204C located between the optical mirror 204B and the second SOA 206B, which will be combined with Figure 3 Provide detailed explanation.

[0061] See also Figure 3 , diagram 300 shows an optical amplification circuit 302 according to various embodiments of the present disclosure. Figure 3 Will combine Figure 1 and Figure 2 The optical amplifier circuit 302 may correspond to Figure 1 The optical amplifier circuit 122 shown in FIG. Figure 3In the illustrated embodiment, the optical amplification circuit 302 may include an input interface 304, a pair of optical amplifiers 306A and 306B, and an output interface 308. In various embodiments, the input interface 304 may be configured to receive an unpolarized optical signal 310. In one example, the unpolarized optical signal 310 may include TE and TM mode components. The input interface 304 may be further configured to output a first polarization component 312 and a second polarization component 316 based on the unpolarized optical signal 310. In order to output the first polarization component 312 and the second polarization component 316, the input interface 304 may include a polarization splitter 304A, an optical mirror 304B, and a polarization converter 304C.

[0062] In many embodiments, the polarization splitter 304A can be arranged within the input interface 304 in a manner that the polarization splitter 304A receives the unpolarized optical signal 310. The polarization splitter 304A can be configured to split the unpolarized optical signal 310 into a first polarization component 312 and a third polarization component 314. The third polarization component 314 can be orthogonal to the first polarization component 312. For example, the first polarization component 312 and the third polarization component 314 can correspond to TM and TE mode components, respectively. The polarization splitter 304A can be further configured to allow the first polarization component 312 corresponding to the TM mode component to pass through it toward the first optical amplifier 306A in a pair of optical amplifiers 306A and 306B. In addition, the polarization splitter 304A can be configured to reflect the third polarization component 314 corresponding to the TE mode component toward the optical mirror 304B.

[0063] In a further embodiment, the optical mirror 304B may be positioned below the polarization splitter 304A so that the optical mirror 304B receives the third polarization component 314 reflected by the polarization splitter 304A. The optical mirror 304B may be configured to direct the third polarization component 314 toward the polarization converter 304C. For example, the optical mirror 304B may reflect the received third polarization component 314 by 90° so as to direct the third polarization component 314 toward the polarization converter 304C.

[0064] In many embodiments, the polarization converter 304C can be positioned adjacent to the optical mirror 304B so that the polarization converter 304C receives the third polarization component 314. The polarization converter 304C can be configured to convert the third polarization component 314 to a second polarization component 316. In one example, the second polarization component 316 can be orthogonal to the third polarization component 314. For example, if the third polarization component 314 corresponds to a TE mode component, the second polarization component 316 can correspond to a TM mode component. The polarization converter 304C can be further configured to direct the second polarization component 316 to the second optical amplifier 306B in the pair of optical amplifiers 306A and 306B.

[0065] In further embodiments, a pair of optical amplifiers 306A and 306B may be disposed between the input interface 304 and the output interface 308. Specifically, the first optical amplifier 306A may be positioned such that the first optical amplifier 306A faces the polarization splitter 304A for receiving the first polarization component 312. In addition, the second optical amplifier 306B may be positioned such that the second optical amplifier 306B faces the polarization converter 304C for receiving the second polarization component 316. The first optical amplifier 306A and the second optical amplifier 306B may be configured to amplify the first polarization component 312 and the second polarization component 316, respectively.

[0066] In further embodiments, a pair of optical amplifiers 306A and 306B may correspond to a pair of SOAs having PDG curves. Figure 3 In the illustrated embodiment, each of the PDG curves may indicate that the optical gain of the respective optical amplifier of the pair of optical amplifiers 306A and 306B is dominant for the TM mode component. In various embodiments, the pair of optical amplifiers 306A and 306B may amplify the first polarization component 312 and the second polarization component 316 according to the PDG curves. For example, the first optical amplifier 306A may amplify the first polarization component 312 according to the PDG curve of the first optical amplifier 306A. In addition, the first optical amplifier 306A may output the amplified first polarization component 318 according to the amplified first polarization component 312. Similarly, the second optical amplifier 306B may output the amplified second polarization component 320 by amplifying the second polarization component 316 using the PDG curve of the second optical amplifier 306B.

[0067] In various embodiments, the output interface 308 may be configured to receive the amplified first polarization component 318 and the amplified second polarization component 320 and output a non-polarized optical signal 324. For example, the non-polarized optical signal 324 may correspond to an amplified version of the non-polarized optical signal 310. To output the non-polarized optical signal 324, the output interface 308 may include a polarization combiner 308A, an optical mirror 308B, and a polarization converter 308C.

[0068] In various embodiments, the polarization converter 308C can be positioned within the output interface 308 so that the polarization converter 308C faces the first optical amplifier 306A to receive the amplified first polarization component 318. The polarization converter 308C can be configured to convert the amplified first polarization component 318 into an amplified third polarization component 322. In one example, the amplified third polarization component 322 can be orthogonal to the amplified first polarization component 318. For example, if the amplified first polarization component 318 corresponds to a TM mode component, the amplified third polarization component 322 can correspond to a TE mode component. The polarization converter 308C can be further configured to direct the amplified third polarization component 322 to the optical mirror 308B.

[0069] In several embodiments, the optical mirror 308B can be positioned adjacent to the polarization converter 308C so that the optical mirror 308B receives the amplified third polarization component 322. The optical mirror 308B can be configured to direct the amplified third polarization component 322 toward the polarization combiner 308A. For example, the optical mirror 308B can reflect the amplified third polarization component 322 by 90° so as to direct the amplified third polarization component 322 toward the polarization combiner 308A.

[0070] In several other embodiments, the polarization combiner 308A may be disposed below the optical mirror 308B in a manner that the polarization combiner 308A faces the second optical amplifier 306B. The polarization combiner 308A may be configured to receive the amplified second polarization component 320 and the amplified third polarization component 322. In addition, the polarization combiner 308A may be configured to combine the amplified second polarization component 320 corresponding to the TM mode component with the amplified third polarization component 322 corresponding to the TE mode component. In addition, the polarization combiner 308A may output a non-polarized optical signal 324 based on the combination of the amplified second polarization component 320 and the amplified third polarization component 322. For example, the non-polarized optical signal 324 may correspond to an amplified version of the non-polarized optical signal 310.

[0071] Thus, a pair of optical amplifiers 306A and 306B and input interface 304 and output interface 308 can enable optical amplifier circuit 302 to amplify non-polarized optical signal 310 as a polarization-independent amplifier circuit. Although the input interface 304 and output interface 308 are shown to include polarization converters 304C and 308C, respectively, the scope of the present disclosure is not limited thereto. In some further embodiments, such as Figure 4 As shown, input interface 304 and output interface 308 may not include polarization converters 304C and 308C.

[0072] refer to Figure 4 , a schematic diagram 400 of an optical amplification circuit 402 according to various embodiments of the present disclosure is shown. Figure 4 Will combine Figure 1-Figure 3 The optical amplifier circuit 402 may correspond to Figure 1 The optical amplifier circuit 122 shown in FIG. Figure 4In the illustrated embodiment, the optical amplification circuit 402 may include an input interface 404, a pair of optical amplifiers 406A and 406B, and an output interface 408. In various embodiments, the input interface 404 may be configured to receive an unpolarized optical signal 410. In one example, the unpolarized optical signal 410 may include TE and TM mode components. The input interface 404 may be further configured to output a first polarization component 412 and a second polarization component 414 based on the unpolarized optical signal 410. In order to output the first polarization component 412 and the second polarization component 414, the input interface 404 may include a polarization splitter 404A and an optical mirror 404B.

[0073] In many embodiments, the polarization splitter 404A can be positioned within the input interface 404 in a manner that the polarization splitter 404A receives the unpolarized optical signal 410. The polarization splitter 404A can be configured to split the unpolarized optical signal 410 into a first polarization component 412 and a second polarization component 414. For example, the second polarization component 414 can be orthogonal to the first polarization component 412. For example, the first polarization component 412 and the second polarization component 414 can correspond to TM and TE mode components, respectively. The polarization splitter 404A can be further configured to allow the first polarization component 412 corresponding to the TM mode component to pass through it toward the first optical amplifier 406A in a pair of optical amplifiers 406A and 406B. In addition, the polarization splitter 404A can be configured to reflect the second polarization component 414 corresponding to the TE mode component toward the optical mirror 404B.

[0074] In many embodiments, optical mirror 404B can be positioned below polarization splitter 404A so that optical mirror 404B receives second polarization component 414 reflected by polarization splitter 404A. Optical mirror 404B can be configured to direct second polarization component 414 toward second optical amplifier 406B in a pair of optical amplifiers 406A and 406B. For example, optical mirror 404B can reflect received second polarization component 414 by 90° so as to direct second polarization component 414 toward second optical amplifier 406B.

[0075] In further embodiments, a pair of optical amplifiers 406A and 406B may be disposed between the input interface 404 and the output interface 408. Specifically, the first optical amplifier 406A may be positioned such that the first optical amplifier 406A faces the polarization splitter 404A for receiving the first polarization component 412. In addition, the second optical amplifier 406B may be positioned such that the second optical amplifier 406B faces the optical mirror 404B for receiving the second polarization component 414. The first optical amplifier 406A and the second optical amplifier 406B may be configured to amplify the first polarization component 412 and the second polarization component 414, respectively.

[0076] In further embodiments, a pair of optical amplifiers 406A and 406B may correspond to a pair of SOAs having PDG curves. The PDG curves may include a first PDG curve for the first optical amplifier 406A and a second PDG curve for the second optical amplifier 406B. Figure 4 In the illustrated embodiment, the first PDG curve may indicate that the optical gain of the first optical amplifier 406A is dominant over the TM mode component, and the second PDG curve may indicate that the optical gain of the second optical amplifier 406B is dominant over the TE mode component. In various embodiments, a pair of optical amplifiers 406A and 406B may amplify the first polarization component 412 and the second polarization component 414 according to the PDG curve. For example, the first optical amplifier 406A may amplify the first polarization component 412 according to the first PDG curve. In addition, the first optical amplifier 406A may output the amplified first polarization component 416 according to the amplification result of the first polarization component 412. Similarly, the second optical amplifier 406B may output the amplified second polarization component 418 by amplifying the second polarization component 414 using the second PDG curve.

[0077] In various embodiments, the output interface 408 may be configured to receive the amplified first polarization component 416 and the amplified second polarization component 418 and output an unpolarized light signal 420. For example, the unpolarized light signal 420 may correspond to an amplified version of the unpolarized light signal 410. To output the unpolarized light signal 420, the output interface 408 may include a polarization combiner 408A and an optical mirror 408B.

[0078] In several embodiments, the optical mirror 408B may be disposed in the output interface 408 in a manner that the optical mirror 408B faces the second optical amplifier 406B so as to receive the amplified second polarization component 418. The optical mirror 408B may be configured to direct the amplified second polarization component 418 toward the polarization combiner 408A. For example, the optical mirror 408B may reflect the amplified second polarization component 418 by 90° so as to direct the amplified second polarization component 418 toward the polarization combiner 408A.

[0079] In several other embodiments, the polarization combiner 408A may be disposed above the optical mirror 408B in a manner that the polarization combiner 408A faces the first optical amplifier 406A. The polarization combiner 408A may receive the amplified first polarization component 416 and the amplified second polarization component 418. In addition, the polarization combiner 408A may be configured to combine the amplified first polarization component 416 corresponding to the TM mode component with the amplified second polarization component 418 corresponding to the TE mode component. In addition, the polarization combiner 408A may output a non-polarized light signal 420 according to the combination of the amplified first polarization component 416 and the amplified second polarization component 418. For example, the non-polarized light signal 420 may correspond to an amplified version of the non-polarized light signal 410.

[0080] In this way, a pair of optical amplifiers 406A and 406B, together with the input interface 404 and the output interface 408, can enable the optical amplification circuit 402 to act as a polarization-independent amplification circuit for amplifying the non-polarized optical signal 410. Although the polarization combiner 408A and the optical mirror 408B are shown facing the first and second optical amplifiers 406A and 406B, respectively, the scope of the present disclosure is not limited to this. In some examples, if the positions of the polarization splitter 404A and the optical mirror 404B are correspondingly swapped in the input interface 404, the positions of the polarization combiner 408A and the optical mirror 408B can be swapped without departing from the scope of the present disclosure. In more examples, the positions of the polarization combiner 408A and the optical mirror 408B can be swapped without departing from the scope of the present disclosure to provide symmetrical optical losses at least relative to the optical mirrors 404B and 408B.

[0081] Some embodiments are based on the recognition that the optical amplifier circuit 402 can provide optimal optical gain if it operates in a specific wavelength band. For example, the specific wavelength band may correspond to one of the C-band (traditional band), the L-band (long-wave band), or similar bands. Therefore, in order to achieve optimal optical gain in a wide band, the present disclosure provides an optical path. For example, the optical path can be designed to utilize multiple optical amplifier circuits, each of which is customized for a different wavelength band of the wide band. Figure 5 This optical circuit will be described in detail.

[0082] refer to Figure 5 , diagram 500 shows an optical circuit 502 according to various embodiments of the present disclosure. Figure 5 Will combine Figure 1-Figure 4 In various embodiments, the optical circuit 502 may be embodied in Figure 1 The optical IC 104 is shown. Figure 5 In the illustrated embodiment, optical circuit 502 may include optical splitter 504, optical amplification circuits 506A and 506B, optical combiner 508, and waveguides 510A and 510B. In many embodiments, optical splitter 504 may be configured to receive unpolarized input optical signal 512. In one embodiment, optical splitter 504 may include at least one input port and a plurality of output ports. Optical splitter 504 may receive unpolarized input optical signal 512 through its input port. In one example, unpolarized input optical signal 512 may have a set of characteristics. For example, the set of characteristics may correspond to at least one of a multi-wavelength band of unpolarized input optical signal 512 or a specific power level of unpolarized input optical signal 512.

[0083] In further embodiments, the optical splitter 504 may be configured to split the non-polarized input optical signal 512 into the non-polarized optical signals 514 and 516 according to a set of characteristics. In some embodiments, the optical splitter 504 may correspond to a wavelength division multiplexer (WDM Demux) that splits the non-polarized input optical signal 512 into the non-polarized optical signals 514 and 516 according to the multi-wavelength bands of the non-polarized input optical signal 512. In one example, the wavelength division multiplexer may split the non-polarized input optical signal 512 into the non-polarized optical signals 514 and 516 such that each of the non-polarized optical signals 514 and 516 has a different wavelength band in the multi-wavelength bands of the non-polarized input optical signal 512. For example, if the unpolarized input optical signal 512 corresponds to a composite optical signal having at least one wavelength in the C-band and at least one wavelength in the L-band, the wavelength division multiplexer may split the unpolarized input optical signal 512 into an unpolarized optical signal 514 having a wavelength in the C-band and an unpolarized optical signal 516 having a wavelength in the L-band.

[0084] In some further embodiments, the optical splitter 504 may correspond to a power divider that divides the non-polarized input optical signal 512 into non-polarized optical signals 514 and 516 based on a specific power level of the non-polarized input optical signal 512. In one example, the power divider may divide the non-polarized input optical signal 512 into the non-polarized optical signals 514 and 516 so that each of the non-polarized optical signals 514 and 516 has a specific power ratio relative to the power level of the non-polarized input optical signal 512. For example, the specific power ratio of each of the non-polarized optical signals 514 and 516 may be 0.5. After dividing the non-polarized input optical signal 512, the optical splitter 504 may output the non-polarized optical signals 514 and 516 to the optical amplification circuits 506A and 506B through its multiple output ports.

[0085] In many embodiments, optical amplification circuits 506A and 506B may be coupled to optical splitter 504. In one example, optical amplification circuits 506A and 506B may be coupled to optical splitter 504 via waveguide 510A. For example, waveguide 510A may correspond to Figure 1 In one embodiment, the optical amplifier circuits 506A and 506B can be customized to operate in the C-band and L-band, respectively, to amplify the unpolarized optical signals 514 and 516.

[0086] In many embodiments, each of the optical amplifier circuits 506A and 506B may include an input interface, a pair of optical amplifiers having a PDG curve, and an output interface. In these embodiments, each of the optical amplifier circuits 506A and 506B may be configured to receive a respective non-polarized optical signal in the non-polarized optical signals 514 and 516. For example, the optical amplifier circuits 506A and 506B may receive the non-polarized optical signals 514 and 516, respectively. In addition, each of the optical amplifier circuits 506A and 506B may be configured to amplify the respective non-polarized optical signal according to its corresponding PDG curve. In addition, each of the optical amplifier circuits 506A and 506B may be configured to output the respective amplified non-polarized optical signal according to the amplification result. For example, the optical amplifier circuits 506A and 506B may output the amplified non-polarized optical signals 518 and 520, respectively. In one example, the amplified non-polarized optical signals 518 and 520 may correspond to amplified versions of the non-polarized optical signals 514 and 516, respectively. For example, each of the optical amplifier circuits 506A and 506B may correspond to Figure 2-Figure 4 One of the optical amplification circuits 202, 302 or 402 described in the detailed description of FIG.

[0087] In further embodiments, the optical amplifier circuits 506A and 506B may be further coupled to the optical combiner 508 via the waveguide 510B. For example, the waveguide 510B may correspond to Figure 1 The optical combiner 508 may include a plurality of input ports and at least one output port. In various embodiments, the optical combiner 508 may be configured to receive the amplified unpolarized optical signals 518 and 520. For example, the optical combiner 508 may receive the amplified unpolarized optical signals 518 and 520 from the optical amplification circuits 506A and 506B through its plurality of input ports. In addition, the optical combiner 508 may be configured to output an unpolarized output optical signal 522 by combining the amplified unpolarized optical signals 518 and 520. In some embodiments, the optical combiner 508 may correspond to a wavelength division multiplexer (WDM) that combines the amplified unpolarized optical signals 518 and 520 according to their wavelengths to output the unpolarized output optical signal 522. In some other embodiments, the optical combiner 508 may correspond to a power combiner that combines the amplified unpolarized optical signals 518 and 520 according to their power levels to output the unpolarized output optical signal 522. In one example, the unpolarized output optical signal 522 may correspond to an amplified version of the unpolarized input optical signal 512 .

[0088] Thus, the optical amplifier circuits 506A and 506B can be used in the optical circuit 502 to provide optimal optical gain for a wide band. Although the optical circuit 502 is shown to include two optical amplifier circuits 506A and 506B for providing optimal optical gain for a wide band, the scope of the present disclosure is not limited thereto. In some embodiments, if the input unpolarized optical signal (e.g., the unpolarized input optical signal 512) has wavelengths of multiple wavelength bands, the optical circuit 502 may include multiple optical amplifier circuits.

[0089] refer to Figure 6 , a flowchart of a light amplification method 600 according to various embodiments of the present disclosure is shown. Figure 6 Will combine Figure 2-Figure 4 For example, the optical amplification method 600 may be Figure 2-Figure 4 The optical amplification method 600 may be implemented in one or more optical amplification circuits 202, 302, or 402 described in the detailed description of the optical amplification method 600. Starting from block 602, the optical amplification method 600 may include receiving an unpolarized optical signal. In one example, the optical amplification circuit 202, 302, or 402 may receive the unpolarized optical signal through at least one waveguide. For example, the received unpolarized optical signal may include TE and TM mode components.

[0090] At block 604, the optical amplification method 600 may include obtaining a first polarization component and a second polarization component according to the unpolarized optical signal. In one example, the first polarization component and the second polarization component may be obtained by one or more input interfaces 204, 304, or 404 by branching the unpolarized optical signal. In some embodiments, each of the first polarization component and the second polarization component may correspond to a TE mode component. In more embodiments, each of the first polarization component and the second polarization component may correspond to a TM mode component. In some further embodiments, the first polarization component and the second polarization component may correspond to TE and TM mode components.

[0091] At block 606, the optical amplification method 600 may include amplifying the first polarization component and the second polarization component. For example, the amplification of the first polarization component and the second polarization component may include increasing the signal strength and / or power level of the first polarization component and the second polarization component. In one example, the first polarization component and the second polarization component may be respectively Figure 2-Figure 4 Amplification is performed by one or more of a pair of optical amplifiers 206A and 206B, 306A and 306B, or 406A and 406B described in the detailed description.

[0092] At block 608, the optical amplification method 600 may include outputting an amplified version of the unpolarized optical signal based on the amplified first polarization component and the amplified second polarization component. For example, the amplified version of the unpolarized optical signal may be output by one or more output interfaces 208, 308, or 408. In one example, the amplified version of the unpolarized optical signal may have a greater signal strength and / or power level than the signal strength and / or power level of the received unpolarized optical signal.

[0093] Among other features, technology consistent with the present disclosure provides optical circuits, optical amplifier circuits, and optical amplification methods for amplifying unpolarized optical signals. Although various exemplary embodiments of the disclosed optical circuits, optical amplifier circuits, and optical amplification methods have been described above, it should be understood that these embodiments are for illustrative purposes only and not limiting. It is not exhaustive and does not limit the present disclosure to the precise form disclosed. Modifications and variations may be made based on the above teachings and may be obtained from the practice of the present disclosure without departing from the breadth or scope of the present disclosure.

[0094] Although various embodiments of the present disclosure have been illustrated and described, it is apparent that the present disclosure is not limited to these embodiments. For those skilled in the art, many modifications, changes, variations, substitutions and equivalents will be apparent without departing from the spirit and scope of the present disclosure described in the claims.

Claims

1. An optical amplifier circuit, characterized in that: include Input interface, configured as: receiving an unpolarized light signal; and Outputting a first polarization component and a second polarization component according to the unpolarized light signal; a pair of optical amplifiers, coupled to the input interface, wherein The pair of optical amplifiers has a polarization dependent gain (PDG) curve; and The pair of optical amplifiers is configured to amplify the first polarization component and the second polarization component according to the PDG curve; as well as An output interface is coupled to the pair of optical amplifiers, wherein the output interface is configured to output an amplified version of the unpolarized optical signal based on the amplified first polarization component and the amplified second polarization component.

2. The optical amplifier circuit according to claim 1, characterized in that: The input interface comprises: a polarization splitter configured to separate the unpolarized optical signal into the first polarization component and a third polarization component, wherein the third polarization component is orthogonal to the first polarization component; and A polarization converter is configured to convert the third polarization component into the second polarization component.

3. The optical amplifier circuit according to claim 2, characterized in that: Each of the first polarization component and the second polarization component corresponds to a transverse electric TE mode component; and The third polarization component corresponds to a transverse magnetic TM mode component.

4. The optical amplifier circuit according to claim 3, characterized in that: Each of the PDG curves indicates that the optical gain of the respective optical amplifier in the pair of optical amplifiers is dominated by the TE mode component.

5. The optical amplifier circuit according to claim 3, characterized in that: The pair of optical amplifiers includes a first optical amplifier and a second optical amplifier; The input interface further comprises an optical mirror; The polarization splitter is further configured as: allowing the third polarization component to pass toward the polarization converter; and reflecting the first polarization component to the optical mirror; The polarization converter is further configured to output the second polarization component to the first optical amplifier according to the conversion of the third polarization component; and The optical mirror is configured to direct the first polarization component toward the second optical amplifier.

6. The optical amplifier circuit according to claim 2, characterized in that: Each of the first polarization component and the second polarization component corresponds to a transverse magnetic TM mode component; and The third polarization component corresponds to the transverse electric TE mode component.

7. The optical amplifier circuit according to claim 6, characterized in that: Each of the PDG curves indicates that the optical gain of the respective optical amplifier in the pair of optical amplifiers is dominated by the TM mode component.

8. The optical amplifier circuit according to claim 6, characterized in that: The pair of optical amplifiers includes a first optical amplifier and a second optical amplifier; The input interface also includes an optical mirror; The polarization splitter is configured as: allowing the first polarization component to pass toward the first optical amplifier; and reflecting the third polarization component to the optical mirror; The optical mirror is configured to direct the third polarization component to the polarization converter; as well as The polarization converter is configured to output the second polarization component to the second optical amplifier according to conversion of the third polarization component.

9. The optical amplifier circuit according to claim 1, characterized in that: The output interface includes an optical mirror and a polarization combiner; The optical mirror is configured to direct the amplified first polarization component to the polarization combiner; and The polarization combiner is configured as: combining the amplified first polarization component and the amplified second polarization component; and An amplified version of the unpolarized light signal is output based on a combination of the amplified first polarization component and the amplified second polarization component.

10. The optical amplifier circuit according to claim 9, characterized in that: The pair of optical amplifiers includes a first optical amplifier and a second optical amplifier, The output interface further comprises a polarization converter; and The polarization converter is located between the first optical amplifier and the optical mirror or between the second optical amplifier and the polarization combiner.

11. The optical amplifier circuit according to claim 1, characterized in that: The first polarization component corresponds to a transverse magnetic TM mode component, and the second polarization component corresponds to a transverse electric TE mode component.

12. The optical amplifier circuit according to claim 11, characterized in that: The pair of optical amplifiers includes a first optical amplifier and a second optical amplifier; The input interface includes a polarization splitter and an optical mirror; The polarization splitter is configured as: Splitting the unpolarized light signal into the first polarization component and the second polarization component; allowing the first polarization component to pass toward the first optical amplifier; and reflecting the second polarization component to the optical mirror; and The optical mirror is configured to direct the second polarization component toward the second optical amplifier.

13. The optical amplifier circuit according to claim 12, characterized in that: The PDG curves include a first PDG curve associated with the first optical amplifier and a second PDG curve associated with the second optical amplifier; The first PDG curve indicates that the optical gain of the first optical amplifier plays a dominant role in the TM mode component; and The second PDG curve indicates that the optical gain of the second optical amplifier dominates the TE mode component.

14. The optical amplifier circuit according to claim 1, characterized in that: The pair of optical amplifiers includes a pair of semiconductor optical amplifiers SOA.

15. The optical amplifier circuit according to claim 14, characterized in that: Also included is an amplification control circuit configured to: generating a drive current for each SOA in the pair of SOAs; and Based on the generated drive current, the amplification of each SOA in the pair of SOAs is controlled.

16. An optical circuit comprising: Optical splitter, configured as: receiving an unpolarized input optical signal having a set of characteristics; as well as splitting the unpolarized input optical signal into a plurality of unpolarized optical signals according to the set of characteristics; A plurality of optical amplification circuits are coupled to the optical splitter, wherein Each of the plurality of optical amplification circuits includes a pair of optical amplifiers having a polarization dependent gain (PDG) curve; and Each of the plurality of optical amplification circuits is configured as: receiving a respective unpolarized light signal among the plurality of unpolarized light signals; amplifying the respective unpolarized light signals according to the PDG curve; and outputting a respective amplified unpolarized light signal among a plurality of amplified unpolarized light signals; as well as An optical combiner coupled to the plurality of optical amplification circuits, wherein the optical combiner is configured as follows: receiving a plurality of amplified unpolarized optical signals; combining the plurality of amplified unpolarized optical signals; and Based on the combination of the plurality of amplified unpolarized optical signals, an amplified version of the unpolarized input optical signal is output.

17. The optical circuit according to claim 16, characterized in that The set of characteristics corresponds to at least one of a plurality of wavelength bands of the unpolarized input optical signal or a power level of the unpolarized input optical signal.

18. The optical circuit according to claim 17, characterized in that Each of the plurality of unpolarized optical signals has a specific wavelength band among the multiple wavelength bands of the unpolarized input optical signal.

19. The optical circuit according to claim 17, characterized in that Each of the plurality of unpolarized optical signals has a specific power ratio relative to a power level of the unpolarized input optical signal.

20. A light amplification method, characterized in that: include: In an optical amplification circuit including a pair of optical amplifiers having polarization dependent gain (PDG) curves: receiving an unpolarized optical signal; Acquire a first polarization component and a second polarization component according to the unpolarized light signal; amplifying the first polarization component and the second polarization component according to the PDG curve; as well as An amplified version of the unpolarized optical signal is outputted based on the amplified first polarization component and the amplified second polarization component.

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