Transmissive optical repeaters for satellites and communications satellites equipped with transmissive optical repeaters for satellites
The transmissive optical repeater optimizes satellite communication by independently amplifying orthogonal polarizations, addressing mass, power, and volume challenges, enabling efficient data transfer and flexible operation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- THALES SA
- Filing Date
- 2025-12-17
- Publication Date
- 2026-06-29
AI Technical Summary
Existing optical repeaters for satellite communication systems face challenges with high mass, power consumption, and volume due to complex hardware configurations, especially when using polarization-dependent amplifiers, which also require higher power and compromise signal quality.
A transmissive optical repeater design that separates and amplifies orthogonal polarizations independently, using a polarization separator and controller to optimize power usage and maintain signal quality without regenerating the signal, integrated with optional external processing for enhanced flexibility.
The design achieves efficient large-scale data transfer between ground stations with reduced mass, power, and volume, while maintaining link budget and capacity, allowing for flexible operation in both transparent and regenerative modes.
Smart Images
Figure 2026106451000001_ABST
Abstract
Description
Technical Field
[0001] This patent application claims the benefit of French Patent Application No. 24 / 14329, filed on December 17, 2024, and is incorporated herein by reference.
Background Art
[0002] The present invention relates to the field of satellite communication systems. More specifically, as shown in FIG. 1, it relates to a free space optical link, abbreviated as "FSO", for transferring large amounts of data, or "trunking", between remote optical ground stations SSO1 and SSO2 via a communication satellite SAT equipped with an optical repeater.
[0003] The present invention can also be implemented in links between optical stations that do not exist on the ground, such as optical ground stations, satellites equipped with transparent repeaters, and "optical stations" of other satellites, or in links between the "optical stations" of satellites, satellites equipped with transparent repeaters, and "optical stations" of other satellites. A regenerative optical repeater as shown in FIG. 2 is already known, and this solution includes means for optical / electrical (O / E) detection and decoding, ultra-high-speed digital processing, and electrical / optical (E / O) re-emission by a laser source and a modulator, in addition to conventional optical elements (amplifiers, demultiplexers, multiplexers, etc.) of the terminal.
[0004] The above-mentioned high-speed digital processing means are integrated in the form of a digital processor (abbreviated as "onboard processor": OBP, external processor) mounted on the satellite.
[0005] The regenerative optical repeater has a very complex hardware configuration when mounted on a satellite, thus having a significant impact on mass, power consumption, and mounting volume. In addition to problems related to the feasibility of high-speed digital technology and compatibility with the space environment, the above-mentioned specifications such as mass involve high additional costs. Furthermore, the above-mentioned solution depends on the modulation method (waveform).
[0006] In the example shown in Figure 2, the regenerative optical repeater has the following configuration: • A set of optical fiber FOs for transferring optical signals between the repeater's optical element and the digital connection CN at the input and output of the digital processor OBP. • First optical head OHU1 configured to collect and focus optical signals with two orthogonally polarized fields and orthogonal defects of less than 10°. • Low-noise optical amplifier LNOA configured to amplify the optical signal transmitted at the output of the first optical head OHU1 with less than 6dB of noise. • A WDM optical demultiplexer configured to separate the signal transmitted at the output of a low-noise optical amplifier (LNOA) by wavelength and transmit the wavelength-separated signals to multiple output channels corresponding to each wavelength. • Optical / electrical converter (O / E) that converts signals from the output channel of an optical demultiplexer (WDM). The OBP digital processor demodulates the output signal of the optical / electrical converter (O / E), performs digital processing, and then modulates the output signal. • Electrical / optical converter E / O that converts signals from the output channels of the digital processor OBP. • One high-power optical amplifier (HPOA) per output channel of the electrical / optical converter E / O. • High-power optical multiplexer (HPWDM) that multiplexes the output signal of the high-power optical amplifier (HPOA). • Second optical head OHU2 configured to transmit the output optical signal of the high-power optical multiplexer HPWDM. It is composed of.
[0007] As shown in Figure 3, transmissive optical repeaters with polarization-independent HPOAs are also known. Such solutions, i.e., the aforementioned transmissive optical repeaters, include only conventional optical means and elements (amplifiers, demultiplexers, filters, power amplifiers, multiplexers, etc.) and do not include demodulation means or ultrafast digital processing or E / O re-emission using a laser source and modulator. All-optical repeaters require significantly higher power (typically +3dB) than state-of-the-art technology to ensure the link budget for the target speed, and it is necessary that the signal quality is not regenerated on the board.
[0008] In the example shown in Figure 3, the transmissive optical repeater has the following configuration: • A set of optical fiber FOs for transferring optical signals between the optical elements of a repeater. • A first optical head OHU1 configured to collect and focus optical signals having two orthogonally polarized signals with orthogonal defects of less than 10°. • Low-noise optical amplifier LNOA configured to amplify the optical signal transmitted at the output of the first optical head OHU1 with less than 6dB of noise. • A WDM optical demultiplexer configured to separate the signal transmitted at the output of a low-noise optical amplifier (LNOA) by wavelength and transmit the wavelength-separated signals to multiple output channels corresponding to each wavelength. • LOFA (Low-Output Optical Amplifier) for each wavelength of the output channel of the WDM optical demultiplexer. • Optical bandpass filter (BPF) configured to filter noise from the output channel of the second optical amplifier (LOFA). • Third high-power optical amplifier (HPOA) for each output channel of the optical bandpass filter (BPF) • High-power optical multiplexer (HPWDM) that multiplexes signals from the third high-power optical amplifier (HPOA). • Second optical head OHU2 configured to transmit the output optical signal of the high-power optical multiplexer HPWDM. It is composed of.
[0009] However, the highest optical power is usually obtained by using a polarization-dependent amplifier, that is, by amplifying only one polarization state.
[0010] Using polarization-dependent amplifiers is advantageous in order to close the link budget and / or maximize the link capacity (speed).
[0011] In fact, when the output power is fixed, if each polarization is amplified individually by a dedicated power amplifier, the total power increases by approximately 3 dB.
[0012] Furthermore, the use of polarization-dependent amplifiers may be necessary for performance reasons (such as facilitating gain balancing) or for availability reasons.
[0013] Furthermore, transmissive optical repeaters equipped with an upstream polarization maintenance function that maintains the polarization state throughout the entire optical repeater mounted on the satellite are also known. [Overview of the project]
[0014] Therefore, an object of the present invention is to propose an optical repeater that can create a free-space optical link compatible with signals in one or two orthogonal polarization states without compromising budget or performance in terms of mass, consumption, and volume (MCV), enabling large-scale data transfer between two geostationary ground stations and configured for integration into a satellite. [Means for solving the problem]
[0015] For the purposes described above, the present invention relates to a transmissive optical repeater configured to be mounted on a satellite, and has the following configuration; • A set of optical fibers for transferring optical signals between elements of an optical repeater. • A first optical head configured to collect and focus two orthogonal polarizations of optical signals, with an orthogonality defect of less than 10°. · A low-noise optical amplifier configured to amplify an optical signal transmitted in the output of the first optical head with an additional noise of less than 6 dB · A polarization separator and controller disposed downstream of the low-noise optical amplifier, comprising a channel polarization separator and a controller for each input channel, configured to separate signals according to two orthogonal polarizations, control the polarization of the signals, and send the separated polarization signals to two respective outputs · A third high-output optical amplifier (high-output optical amplifier) for each output channel of the polarization separator and controller · A polarization coupler disposed downstream of the polarization separator and controller, configured to recombine signals from two input channels · A second optical head configured to transmit the output optical signal of the orthogonally polarized wave coupler It comprises.
[0016] In one embodiment, the transparent optical repeater has the following configuration; · An optical demultiplexer disposed between the low-noise optical amplifier and the polarization separator and controller, configured to separate the signal transmitted at the output of the low-noise optical amplifier for each wavelength and send the signals separated for each wavelength to a plurality of output channels corresponding to each wavelength · An optical multiplexer disposed between the third high-output optical amplifier and the orthogonally polarized wave coupler with a set of output channels of the same polarization It comprises.
[0017] According to one embodiment, the transparent optical repeater comprises a second optical amplifier for the wavelength of each input channel of the polarization separator and controller.
[0018] In one embodiment, the transparent optical repeater comprises an optical bandpass filter configured to filter the noise from the input channels of the polarization separator and controller.
[0019] According to one embodiment, the transmissive optical repeater includes an optical switch for each input channel of a polarization beam splitter and a controller, and is configured to transfer an optical signal to an external satellite processing device via another optical fiber and to be able to retransmit it to the polarization beam splitter and the controller after being processed by the external satellite processing device.
[0020] In one embodiment, the external satellite processing device includes an external processor.
[0021] According to one embodiment, the channel polarization beam splitter and the controller have the following configuration; · A polarization controller configured to change the polarization of an optical signal according to a command · A polarization beam splitter configured to separate signals according to two orthogonal polarizations in each of two channels · One (polarization tracking control module by a polarization feedback loop) for each output channel of the channel polarization beam splitter and the controller It includes.
[0022] According to one embodiment, the channel polarization beam splitter and the controller are configured to use low-frequency RF tone detection, and the polarization tracking control module includes a polarization tracking control module and a module for minimizing one polarization or maximizing the other orthogonal polarization. Another polarization tracking control module includes a polarization tracking control module and a module for minimizing the other polarization or maximizing the other polarization.
[0023] In one embodiment, the channel polarization beam splitter and the controller include a polarization tracking module configured to use optical power detection to maximize the power of a useful output channel and minimize the power of other output channels when the received signal has only one polarization.
[0024] According to one embodiment, the channel polarization separator and controller comprises a polarization tracking module configured to detect a portion of the optical flow of a single polarization channel using a coherent receiver, and a digital processor configured to quantify the ratio of two polarizations and feed back to the polarization controller such that the polarization channel containing the tracking module contains only one polarization.
[0025] In one embodiment, the channel polarization separator and controller include a polarization tracking module configured to use interference detection of signals from two polarization channels.
[0026] According to one embodiment, interference detection of signals from two polarization channels is performed using Hansch-Couillaud (HC) detection.
[0027] In one embodiment, interference detection of signals from two polarization channels is heterodyne detection.
[0028] According to another aspect of the present invention, a communications satellite equipped with a transmissive optical repeater as described above has also been proposed.
[0029] The present invention is described as a non-limiting example and can be more preferably understood by considering several embodiments illustrated in the accompanying drawings. [Brief explanation of the drawing]
[0030] [Figure 1] This schematic diagram illustrates the transfer of large amounts of data between remote optical ground stations via a communications satellite, based on the latest technology. [Figure 2] This is a schematic diagram of a regenerative optical repeater for communications satellites, and it is a diagram based on the latest technology. [Figure 3] This is a schematic diagram of a transmissive optical repeater for communications satellites using the latest technology. [Figure 4A] This is a schematic diagram of a transmissive optical repeater for a communications satellite according to one aspect of the present invention. [Figure 4B]This is a schematic diagram of a transmissive optical repeater for a communications satellite according to various embodiments of the present invention. [Figure 5] Figure 4A is a schematic diagram of a transmissive optical repeater for a communications satellite that can operate in regeneration mode. [Figure 6] This is a schematic diagram of an embodiment of a channel polarization separator and controller according to one aspect of the present invention. [Figure 7] Figure 6 is a schematic diagram showing an embodiment of the channel polarization separator and controller according to an aspect of the present invention. [Figure 8] Figure 6 is a schematic diagram showing an embodiment of the channel polarization separator and controller according to an aspect of the present invention. [Figure 9] Figure 6 is a schematic diagram showing an embodiment of the channel polarization separator and controller according to an aspect of the present invention. [Figure 10] Figure 6 is a schematic diagram showing an embodiment of the channel polarization separator and controller according to an aspect of the present invention. [Modes for carrying out the invention]
[0031] In all figures, the same reference numerals indicate the same components.
[0032] Figure 4A schematically shows a transmissive optical repeater for a communications satellite according to one aspect of the present invention.
[0033] A transmissive optical repeater configured for installation on a satellite has the following configuration: • A set of optical fiber FOs for transferring optical signals between elements of an optical repeater. • A first optical head OHU1 configured to collect and focus two optical signals with orthogonal polarizations having orthogonal defects of less than 10°. The low-noise optical amplifier LNOA is configured to amplify the optical signal transmitted at the output of the first optical head OHU1 with less than 6 dB of noise. • A low-noise optical amplifier (LNOA) is positioned downstream of the low-noise optical amplifier (LNOA), and each input channel is equipped with one channel polarization separation controller (C-PCS), configured to separate signals according to two orthogonalizable polarizations, control the polarization of the signals, and transmit separate polarized signals to their respective outputs. • Polarization separation controller PCS has a third high-power optical amplifier (HPOA) for each output channel. • A quadrature polarization coupler (PBC) located downstream of the polarization separation controller (PCS) and configured to recombine signals from the two input channels. • Second optical head OHU2 configured to transmit the output optical signal of the orthogonal polarization coupler PBC. It is composed of.
[0034] The terms upstream and downstream can be understood in relation to the direction of signal transmission.
[0035] The present invention includes a series of optical elements (such as amplifiers, demultiplexers, and multiplexers) that maintain the continuity of light throughout the entire path of a communication signal.
[0036] Furthermore, a more central stage following channeling (i.e., optical multiplexing) after the fiber input section includes polarization separation by an active control device and channel PCS.
[0037] Optical signals are processed by polarization. That is, in the case of bipolarization, they are separated into two orthogonal components, and in the case of single polarization, they are perfectly projected onto one of two orthogonal states.
[0038] The output stage consists of a polarization-dependent third high-power optical amplifier, which ensures that all available output is supplied to only one polarization state.
[0039] Next, the different channels are recombined by the high-power optical multiplexers HPWDM1 and HPWDM2, for each set of output channels with the same polarization. The orthogonal polarization channels are finally recombined by the orthogonal polarization coupler PBC. Advantageously, the orthogonal polarization coupler PBC is a separate device from the polarization separation controller PCS.
[0040] Inserting the aforementioned polarization separation controller PCS allows each polarization to be amplified by the HPOA according to its dedicated polarization, typically resulting in a 3dB gain in output power after recombination, which can, under better conditions, close the double-coupled link budget for a particular rate or increase the total rate.
[0041] Alternatively, the above methods can be used to optimize the capacity (speed) of the transfer link.
[0042] Figure 4B schematically shows a transmissive optical repeater for a communications satellite according to another aspect of the present invention, further comprising optional elements shown by dashed lines, which can be added individually or in combination with the elements of Figure 4A.
[0043] The aforementioned optional elements are, A set including an optical demultiplexer WDM positioned between a low-noise optical amplifier LNOA and a polarization separation controller PCS, configured to separate the signal transmitted at the output of the low-noise optical amplifier LNOA by wavelength and transmit the wavelength-separated signals to multiple output channels corresponding to each wavelength; and high-power optical multiplexers HPWDM1, HPWDM2 positioned between a third high-power optical amplifier HPOA and an orthogonal polarization coupler PBC, comprising a set of output channels with the same polarization. • A set including a WDM optical demultiplexer and a PCS polarization separation controller, each with a wavelength-based LOFA second optical amplifier for each input channel. • Optical bandpass filter (BPF) configured to filter noise from the input channel of the polarization separation controller (PCS). That is the case.
[0044] Figure 5 schematically shows the embodiment of Figure 4B, further comprising optical switches OADS for each output channel of the optical bandpass filter BPF, and configured to transfer the optical signal via another optical fiber to an external satellite processing device (EPD), and to retransmit it to a polarization separation controller PCS after processing by the EPD.
[0045] Using an optical switch OADS, the signal can be routed directly to a polarization separation controller PCS or to an external satellite processing unit EPD.
[0046] For example, an external satellite processing unit (EPD) could be a processor mounted on a communications satellite that functions as a regenerative relay.
[0047] Optical switches (OADS) enable the routing of optical signals for transparent or regenerative operation of the payload, thereby allowing transparent optical repeaters to operate in regenerative mode.
[0048] In the diagram, solid arrows represent the transmission type path, and dashed arrows represent the regenerative type path. In the transmission type, the signal is sent from the optical bandpass filter (BPF) to the polarization separation controller (PCS).
[0049] In playback mode, the uplink signal, or the signal arriving via the first optical head OHU1, is passed from the optical bandpass filter BPF to the external satellite processing unit EPD, where the optical signal is processed.
[0050] When an OBP is used, the optical signal is demodulated. The data from the demodulated signal can be used in the payload and retransmitted as a new optical signal. Such a new downlink optical signal, or signal output from the second optical head OHU2, has the same wavelength but transmits either the same data as the uplink signal or new data. The aforementioned signal output from the OBP is sent to the polarization separation controller PCS via the optical switch OADS.
[0051] Figure 6 schematically shows an embodiment of a channel polarization separation controller C-PCS according to one aspect of the present invention.
[0052] SMF is an abbreviation for "Single Mode Fiber," and it refers to a single-mode optical fiber whose polarization changes freely in response to fiber constraints (temperature, mechanical constraints, etc.).
[0053] PMF stands for "Polarization Maintaining Fiber," and it refers to a single-mode optical fiber that maintains the polarization of light according to two orthogonal intrinsic axes (slow axis and fast axis).
[0054] The channel polarization separation controller C-PCS is, • Polarization controller PC configured to change the polarization of optical signals in response to commands. • A polarizing beam splitter (PBS), where PBS is an abbreviation for "Polarization Beam Splitter," is configured to separate a signal into two paths according to two orthogonal polarizations (polarization1, polarization2), projecting each component onto the eigenaxis of the component's basis, and each output signal contains one of two components (the inverse function of PBC, which is an abbreviation for "Polarization Beam Combiner"). • For each output channel of the channel polarization separation controller C-PCS, polarization tracking control modules PMC1 and PMC2 are involved in the polarization feedback loop. It is equipped with the polarization tracking control modules PMC1 and PMC2. • Sampling and analysis of light polarization • Calculation and generation of control signals applied to the polarization controller PC according to the desired polarization value. To do so.
[0055] Figure 7 schematically shows one embodiment of the channel polarization separation controller C-PCS of Figure 6, which is configured to use low-frequency RF tone detection. The polarization tracking control module PMC1 consists of the polarization tracking control module PMC and module M1 which minimizes polarization (polarization 2) or maximizes polarization (polarization 1). The polarization tracking control module PMC2 consists of the polarization tracking control module PMC and module M2 which minimizes polarization (polarization 1) or maximizes polarization (polarization 2).
[0056] It can be assumed that there is one RF tone or one RF tone per polarization (in the case of a dual-polarization signal, tone fX is inherent in polarization 1 and tone fY is inherent in polarization 2). By analyzing the tone of the output channel signal from polarization 1, the cyclical polarization in this channel can be inferred. Tone analysis is performed with a photodiode.
[0057] If the powers of tone fX and tone fY are measured to be equal, the power distribution of each signal at the base of the polarization state {polarization 1; polarization 2} can be inferred. On the other hand, if the powers of tone and fX are measured to be zero, it can be inferred that only polarization 2 is circulating in this output channel.
[0058] If it is necessary to include all polarization 1 in polarization output channel polarization 1 (and thus include polarization 2 in polarization output channel polarization 2, since the two polarizations are orthogonal), then the polarization controller PC needs to be controlled to minimize the tone f2 of polarization channel polarization 1 (or minimize f1 of polarization channel polarization 2).
[0059] Figure 8 schematically shows one embodiment of the channel polarization separation controller C-PCS of Figure 6, which includes a polarization tracking module PMC configured to use optical power detection when the received signal has only one polarization, thereby maximizing the power of the useful output channel and minimizing the power of the other output channels.
[0060] Polarization tracking control module PMC1 comprises a polarization tracking control module PMC configured to minimize the power of polarization channel; polarization 1 (or to maximize polarization channel; polarization 2), and an output tracking module PM1 for polarization channel; polarization 1. Polarization tracking and control module PMC2 comprises a polarization tracking control module PMC configured to minimize the power of polarization channel; polarization 2 (or to maximize polarization channel; polarization 2), and an output tracking module PM2 for polarization channel; polarization 2.
[0061] Figure 9 schematically shows one embodiment of the channel polarization separation controller C-PCS of Figure 6. The embodiment shown in Figure 9 comprises a polarization tracking module PMC configured to detect a portion of the optical flow of a single polarization channel (in this case, polarization channel; polarization 1) using a coherent receiver RC, and a digital processor DSP configured to quantify the ratio of two polarizations (polarization 1, polarization 2) and feed it back to the polarization controller PC so that only one polarization is contained in the polarization channel including the tracking module.
[0062] Figure 10 schematically shows an embodiment of the channel polarization separation controller C-PCS of Figure 6. The embodiment shown in Figure 10 includes a polarization tracking module PMC configured to use interference detection of signals from two polarization channels; polarization 1 and polarization 2, for example, by Hensch-Quayau detection (DHC).
[0063] Heterodyne detection can be used as a variation of Hensch-Quoyau detection (DHC).
Claims
1. A transmissive optical repeater configured to be mounted on a satellite, A set of optical fibers (FOs) for transferring optical signals between elements of an optical repeater, A first optical head (OHU1) is configured to collect and focus optical signals having two orthogonally polarized (polarization 1, polarization 2) with an orthogonality defect of less than 10°, A low-noise optical amplifier (LNOA) configured to amplify the optical signal transmitted at the output of the first optical head (OHU1) with less than 6 dB of noise, A polarization separation controller (PCS) including a channel polarization separation controller (C-PCS) positioned downstream of a low-noise optical amplifier (LNOA) and configured to separate signals according to two orthogonally adjustable polarizations for each input channel, control the polarization of the signals, and send the polarization-separated signals to their respective outputs, A high-power optical amplifier (HPOA) for each output channel of the polarization separation controller (PCS), A quadrature polarization coupler (PBC) is located downstream of the polarization separation controller (PCS) and configured to recombine signals from the two input channels, A second optical head (OHU2) configured to transmit the output optical signal of a quadrature polarization coupler (PBC), A transmissive optical repeater equipped with the following features.
2. An optical demultiplexer (WDM) is positioned between a low-noise optical amplifier (LNOA) and a polarization separation controller (PCS), configured to separate the signal transmitted at the output of the LNOA by wavelength and transmit the wavelength-separated signals to multiple output channels corresponding to each wavelength. The transmissive optical repeater according to claim 1, comprising one high-power optical multiplexer (HPWDM1, HPWDM2) positioned between a high-power optical amplifier (HPOA) and an orthogonal polarization coupler (PBC) for each set of output channels of the same polarization.
3. The transmissive optical repeater according to claim 1, further comprising an optical amplifier (LOFA) of the wavelength for each input channel of the polarization separation controller (PCS).
4. The transmissive optical repeater according to claim 1, comprising an optical bandpass filter (BPF) configured to filter noise from the input channel of a polarization separation controller (PCS).
5. The transmissive optical repeater according to claim 1, further comprising optical switches (OADS) for each input channel of a polarization decoupling controller (PCS) configured to transfer optical signals to an external satellite processing unit (EPD) via optical fiber, process them in the EPD, and then retransmit them to the PCS.
6. The transmissive optical repeater according to claim 5, comprising an external satellite processing unit (EPD) composed of an external processor (OBP).
7. A channel polarization separation controller (C-PCS), A polarization controller (PC) configured to change the polarization of an optical signal in response to a command, A polarization separator (PBS) configured to separate signals according to two orthogonally selectable polarizations (polarization 1, polarization 2) in each of the two channels, A polarization tracking control module (PMC1, PMC2) with one polarization feedback loop for each output channel of the channel polarization separation controller (C-PCS), The transmissive optical repeater according to claim 1, comprising a channel polarization separation controller (C-PCS) having the following:
8. The channel polarization separation controller (C-PCS) is configured to use low-frequency RF tone detection. A polarization tracking control module (PMC1) includes a polarization tracking control module (PMC) and a module (M1) for minimizing one polarization or maximizing the other orthogonal polarization, The transmissive optical repeater according to claim 7, comprising a polarization tracking control module (PMC) and another polarization tracking control module (PMC2) including a module (M2) for minimizing or maximizing the other polarization.
9. The transmissive optical repeater according to claim 7, comprising a channel polarization separation controller (C-PCS) configured to use optical power detection to maximize the power of a useful output channel and minimize the power of other output channels when the received signal has only one polarization.
10. The transmissive optical repeater according to claim 7, comprising: a channel polarization separation controller (C-PCS) configured to detect a portion of the optical flow of a single polarization channel using a coherent receiver (RC); and a digital processor (DSP) configured to quantify the ratio of two polarizations and feed back to the polarization controller (PMC) so that the polarization channel containing the tracking module has only one polarization.
11. The transmissive optical repeater according to claim 7, comprising a channel polarization separation controller (C-PCS) and a polarization tracking module (PMC) configured to use interference detection of signals from two polarization channels.
12. The transmissive optical repeater according to claim 11, wherein interference detection of signals from two polarization channels is performed by Hensch-Quay detection (DHC).
13. The transmissive optical repeater according to claim 11, wherein interference detection of signals from two polarization channels is heterodyne detection.
14. A communications satellite comprising a transmissive optical repeater according to any one of claims 1 to 13.