Optical signal processing apparatus, methods and coherent receivers

Abstract

This application relates to an optical signal processing apparatus, method, and coherent receiver. The apparatus includes: a first coupler outputting local oscillator light; a second coupler coupling one signal light; a polarization rotating beam splitter connected to the output of the second coupler; a mixer connected to the output of the first coupler; a balanced detector connected to the output of the mixer; and an intensity modulator whose input is connected to the output of the polarization rotating beam splitter and whose output is connected to the input of the mixer. The second coupler couples one signal light and outputs it to the polarization rotating beam splitter. The intensity modulator couples two signal lights with the same polarization state output from the polarization rotating beam splitter to obtain a target signal light, which is then output to the mixer. The mixer mixes the target signal light and the local oscillator light output from the first coupler to obtain two beat frequency lights. The balanced detector converts the two beat frequency lights into electrical signals and outputs them. The technical solution of this application can reduce the consumption of system resources and the cost of equipment.

Description

Technical Field

[0001] This application relates to the fields of optical signal processing and optical devices, and more particularly to an optical signal processing apparatus, method and coherent receiver. Background Technology

[0002] Coherent detection can increase the sensitivity of coherent receivers by increasing the power of the local oscillator light, allowing devices such as lidar to operate at lower transmit power. The coherent receiver is a crucial component in lidar and other devices that use coherent detection. When processing signal light (e.g., the echo signal from lidar), it requires that the polarization states of the signal light and the local oscillator light be matched, meaning their polarization states are completely identical. Only when their polarization states are perfectly matched can the coherent receiver achieve maximum gain.

[0003] To achieve the maximum gain of the coherent receiver, one existing optical signal processing method employs polarization diversity technology to control the polarization states of the signal light and the local oscillator light. However, this existing method requires 2N balanced detectors and 2N analog-to-digital converters connected to these detectors when there are N signal light inputs. This not only increases the size of the equipment but also increases system resource consumption and equipment cost. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this application provides an optical signal processing apparatus, method, and coherent receiver, which can reduce the consumption of system resources and the cost of equipment.

[0005] The first aspect of this application provides an optical signal processing device, including a first coupler that outputs local oscillator light, a second coupler that couples a signal light, a polarization rotating beam splitter connected to the output end of the second coupler, a mixer connected to the output end of the first coupler, and a balanced detector connected to the output end of the mixer. The device also includes an optical intensity modulator whose input end is connected to the output end of the polarization rotating beam splitter and whose output end is connected to the input end of the mixer.

[0006] The second coupler is used to couple one signal beam and output it to the polarization rotating beam splitter;

[0007] The light intensity modulator is used to couple two polarization-state consistent signal lights output from the polarization rotating beam splitter to obtain a target signal light, which is then output to the mixer.

[0008] The mixer is used to mix the target signal light and the local oscillator light output from the first coupler to obtain two beat frequency lights.

[0009] The balanced detector is used to convert the two beat frequency lights into electrical signals and then output them.

[0010] A second aspect of this application provides an optical signal processing method applied to the optical signal processing apparatus provided in the first aspect above, the method comprising:

[0011] After coupling one signal beam, it is output to the polarization rotating beam splitter;

[0012] The two polarization-consistent signal beams output from the polarization rotating beam splitter are coupled together to obtain a target signal beam, which is then output.

[0013] The target signal light and the local oscillator light output from the first coupler are mixed to obtain two beat frequency lights;

[0014] The two beat frequency optical signals are converted into electrical signals and then output.

[0015] A third aspect of this application provides a coherent receiver that includes the optical signal processing apparatus provided in the first aspect.

[0016] The technical solution provided in this application can include the following beneficial effects: Each signal light is coupled by a second coupler and passes through a polarization rotation beam splitter. Although two signal lights with the same polarization state are output, only one balanced detector is ultimately required. This means that N signal lights only require N balanced detectors. After passing through these N balanced detectors, only N other devices such as analog-to-digital converters are needed. Therefore, compared with the prior art, which requires 2N balanced detectors and 2N other devices such as analog-to-digital converters for N signal lights, the technical solution of this application not only saves the required system devices, but also reduces the consumption of system resources and the cost of coherent receivers. This is conducive to the promotion and application of equipment such as lidar that require coherent receivers in the fields of autonomous driving, intelligent robots and other technologies.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0018] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0019] Figure 1 This is a schematic diagram of the structure of the optical signal processing device shown in the embodiments of this application;

[0020] Figure 2 This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0021] Figure 3aThis is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0022] Figure 3b This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0023] Figure 4 This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0024] Figure 5a This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0025] Figure 5b This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0026] Figure 5c This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0027] Figure 5d This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0028] Figure 5e This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0029] Figure 6a This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0030] Figure 6b This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0031] Figure 6c This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0032] Figure 6d This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0033] Figure 6e This is a schematic diagram of the structure of an optical signal processing device shown in another embodiment of this application;

[0034] Figure 7 This is a schematic flowchart illustrating the optical signal processing method in an embodiment of this application. Detailed Implementation

[0035] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of this application, and are therefore merely examples and should not be used to limit the scope of protection of this application. It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which this application pertains.

[0036] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "straight," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this application, "multiple" and "several" mean two or more (including two), unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0039] To achieve maximum gain in the coherent receiver described above, one existing optical signal processing method employs polarization diversity technology to control the polarization states of the signal light and the local oscillator light. Specifically, two polarization rotating beamsplitters are used to decompose the signal light and the local oscillator light into two beams with mutually orthogonal polarization states. That is, one of the two signal beams decomposed by one polarization rotating beamsplitter is mixed with one of the two local oscillator beams decomposed by the other polarization rotating beamsplitter in a mixer and then input into a balanced detector. The other signal beam is mixed with the other of the two local oscillator beams decomposed by the other polarization rotating beamsplitter in a mixer and then input into another balanced detector. The two time-domain signals output from each balanced detector are then subjected to Fast Fourier Transform (FFT) to obtain two frequency-domain signals. Finally, these two frequency-domain signals are superimposed. In this existing method, each signal light requires two balanced detectors before being processed into a time-domain signal, and after being processed into two frequency-domain signals by the balanced detectors, each frequency-domain signal requires a corresponding analog-to-digital converter or other device for further processing. Thus, when there are N signal beams, the existing method described above requires 2N balanced detectors and 2N analog-to-digital converters and other devices, which not only increases the size of the equipment but also increases the system's resource consumption and equipment cost.

[0040] To address the aforementioned issues, embodiments of this application provide an optical signal processing apparatus, method, and coherent receiver, which can reduce system resource consumption and equipment costs.

[0041] The technical solutions of the embodiments of this application are described in detail below with reference to the accompanying drawings.

[0042] See Figure 1 This is a schematic diagram of the optical signal processing device provided in an embodiment of this application. Only the parts relevant to the embodiments of this application are shown to illustrate the technical solution of this application. Figure 1The example optical signal processing device mainly includes a first coupler 101 that outputs local oscillator light, a second coupler 102 that couples one signal light, a polarization rotating beam splitter 103 connected to the output of the second coupler 102, a mixer 104 connected to the output of the first coupler 102, and a balanced detector 105 connected to the output of the mixer 104. In addition, it includes an optical intensity modulator 106 whose input is connected to the output of the polarization rotating beam splitter 103 and whose output is connected to the input of the mixer 104. It should be noted that both the first coupler 101 and the second coupler 102 serve the same function: to couple the incident light to other devices subsequently connected to them. For example, assuming the input to the first coupler 101 is local oscillator light, a coupler with a coupling degree and / or insertion loss corresponding to the actual needs can be selected to couple the incident local oscillator light to the mixer 104. Similarly, a second coupler 102 with a coupling degree and / or insertion loss corresponding to the actual needs can be selected to couple one incident signal light to the polarization rotating beam splitter 103. The polarization rotating beam splitter 103 splits the one signal light coupled from the second coupler 102 into two signal lights with the same polarization state. In one embodiment of this application, the two signal lights with the same polarization state can be two signal lights of the same transverse electric mode (TE mode). In another embodiment of this application, the two signal lights with the same polarization state can be two signal lights of the same transverse magnetic mode (TM mode). It should be noted that the above-mentioned signal light is relative to the local oscillator light and is an optical signal carrying information, such as the echo signal of the laser beam emitted by the lidar returning after encountering an object.

[0043] Figure 1 In the example optical signal processing device, the intensity modulator 106 can couple two polarization-consistent signal lights output from the polarization rotation beam splitter 103 to obtain a target signal light output to the mixer 104. The mixer 104 mixes the target signal light with the local oscillator light output from the first coupler 101 to obtain two beat frequency lights. The balanced detector 105 converts the two beat frequency lights into electrical signals and outputs them. The electrical signals are then processed by subsequent analog-to-digital converters and other devices.

[0044] from Figure 1As can be seen from the example optical signal processing device, each signal light is coupled by the second coupler 102 and passes through the polarization rotation beam splitter 103. Although two signal lights with the same polarization state are output, only one balanced detector 105 is ultimately required. This means that only N balanced detectors 105 are needed for N signal lights. After the output of these N balanced detectors 105, only N other devices such as analog-to-digital converters are needed. Therefore, compared with the prior art, which requires 2N balanced detectors and 2N other devices such as analog-to-digital converters for N signal lights, the technical solution of this application not only saves the required system devices, but also reduces the consumption of system resources and the cost of coherent receivers. This is conducive to the promotion and application of equipment such as lidar that require coherent receivers in the fields of autonomous driving, intelligent robots and other technologies.

[0045] In one embodiment of this application, Figure 1 Example light intensity modulator 106 may include power divider 201 and light intensity detector 202, such as Figure 2 An example of an optical signal processing device. Figure 2 In the example optical signal processing device, the input terminal of power divider 201 is connected to the output terminal of polarization rotating beam splitter 103, the first output terminal of power divider 201 is connected to the input terminal of mixer 104, and the second output terminal of power divider 201 is connected to light intensity detector 202. Light intensity detector 202 can monitor the monitoring signal light output by power divider 201. Under the monitoring of light intensity detector 202, power divider 201 can couple two polarization-consistent signal lights output by polarization rotating beam splitter 103 to obtain one monitoring signal light and one target signal light with an intensity exceeding a first threshold. Figure 2 In the example device, the target signal light with an intensity exceeding a first threshold, obtained by the power divider 201, is output to the mixer 104, while the monitoring signal light enters the light intensity detector 202. In this embodiment, the light intensity detector 202 monitors the monitoring signal light output from the power divider 201 by outputting a light intensity detector current value or voltage value. In other words, when the power divider 201 inputs a monitoring signal light of a certain intensity to the light intensity detector 202, the light intensity detector 202 will output a corresponding light intensity detector current value or voltage value. When a certain value of light intensity detector current value or voltage value is output, it is equivalent to knowing the intensity of the monitoring signal light output from the power divider 201. Since the sum of the intensities of the monitoring signal light and the target signal light output from the power divider 201 is fixed, knowing the intensity of the monitoring signal light output from the power divider 201 is equivalent to knowing the intensity of the target signal light output from the power divider 201. Alternatively, when the intensity of the monitoring signal light output from the power divider 201 is at its minimum, it means that the intensity of the target signal light output from the power divider 201 is at its maximum.

[0046] In another embodiment of this application, Figure 2 The example power divider 201 may include two phase shifters connected to the polarization rotating beam splitter 103 and a third 3dB coupler connected to the two phase shifters, or, in another embodiment of this application, Figure 2 The example power divider 201 may include a third phase shifter and two 3dB couplers connected to the third phase shifter. In the two embodiments described above, the phase shifter can be used to adjust the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter 103 until the light intensity detector current value corresponding to the monitoring signal light output from the power divider 201 is not greater than a second threshold, the light intensity detector voltage value is not greater than a third threshold, or the target signal light output by the power divider 201 has an intensity exceeding a first threshold.

[0047] Specifically, when Figure 2 In the example power divider 201, which includes two phase shifters connected to a polarization rotating beam splitter 103 and a third 3dB coupler 303 connected to the two phase shifters, one end of the first phase shifter 301 is connected to the first output terminal of the polarization rotating beam splitter 103, and the other end of the first phase shifter 301 is connected to the first input terminal of the third 3dB coupler 303. One end of the second phase shifter 302 is connected to the second output terminal of the polarization rotating beam splitter 103, and the other end of the first phase shifter 301 is connected to the second input terminal of the third 3dB coupler 303. The first output terminal of the third 3dB coupler 303 is connected to a mixer 104, and the second output terminal of the third 3dB coupler 303 is connected to a light intensity detector 202. Figure 3a An example of an optical signal processing device. Figure 3aIn the example optical signal processing device, the third 3dB coupler 303 can output a monitoring signal light to the light intensity detector 202 and output a target signal light with an intensity exceeding the first threshold to the mixer 104. The first phase shifter 301 and / or the second phase shifter 302 can adjust the phase of at least one of the two signal lights with the same polarization state output by the polarization rotating beam splitter 103 until the light intensity detector current corresponding to the monitoring signal light output by the third 3dB coupler 303 is not greater than the second threshold or the light intensity detector voltage is not greater than the third threshold. The light intensity detector 202 can be used to monitor the monitoring signal light output by the third 3dB coupler 303 and obtain the light intensity detector current value or voltage value corresponding to the monitoring signal light. Since the sum of the intensities of the monitoring signal light and the intensity target signal light output from the third 3dB coupler 303 is fixed, when the phase of at least one of the two polarization-consistent signal lights output from the polarization rotating beam splitter 103 is adjusted until the light intensity detector current value corresponding to the monitoring signal light output from the third 3dB coupler 303 is no greater than the second threshold, the light intensity detector voltage value is no greater than the third threshold, or the target signal light output from the third 3dB coupler 303 exceeds the first threshold, this embodiment, by setting two phase shifters 301 and 302 to adjust the phase of the two signal lights respectively, has a wider adjustment range and can further improve the ranging performance.

[0048] It should be noted that in some other embodiments of the optical signal processing apparatus, the two polarization-consistent signal beams output from the polarization rotating beam splitter 103 can also have their phase adjusted using only one phase shifter, such as... Figure 3b As shown, the phase of one of the two polarization-consistent signal beams output by the polarization rotating beam splitter 103 can be adjusted using only the phase shifter 304 (the phase shifter 304 is set in the other signal beam path, which is not shown in the figure).

[0049] In another embodiment of this application, when Figure 2 In the example power divider 201, which includes a third phase shifter 403 and two 3dB couplers connected to the third phase shifter 403, the two input terminals of the first 3dB coupler 401 are respectively connected to the two output terminals of the polarization rotating beam splitter 103; the first output terminal of the first 3dB coupler 401 is connected to the input terminal of the third phase shifter 403; the second output terminal of the first 3dB coupler 401 is connected to the first input terminal of the second 3dB coupler 402; the output terminal of the third phase shifter 403 is connected to the second input terminal of the second 3dB coupler 402; the first output terminal of the second 3dB coupler 402 is connected to the mixer 104; and the second output terminal of the second 3dB coupler 402 is connected to the light intensity detector 202. Figure 4An example of an optical signal processing device. Figure 4 In the example optical signal processing device, the third phase shifter 403 can adjust the phase of one of the two polarization-consistent signal lights output by the first 3dB coupler 401 until the light intensity detector current corresponding to the monitoring signal light output by the second 3dB coupler 402 is not greater than a second threshold or the light intensity detector voltage is not greater than a third threshold. The light intensity detector 202 can monitor the monitoring signal light output by the second 3dB coupler 402 and obtain the light intensity detector current value or light intensity detector voltage value corresponding to the monitoring signal light. The second 3dB coupler can be used to output a monitoring signal light to the light intensity detector 202 and output a target signal light with an intensity exceeding the first threshold to the mixer 104. In other embodiments, the third phase shifter 403 can also adjust the phase of the other signal light (not shown in the figure) among the two polarization-consistent signal lights output by the first 3dB coupler 401 until the light intensity detector current value corresponding to the monitoring signal light output by the second 3dB coupler 402 is not greater than the second threshold or the light intensity detector voltage value is not greater than the third threshold.

[0050] It should be noted that the above Figures 3a to 4 The example phase shifter (including the first phase shifter 301, the second phase shifter 302, and the third phase shifter 403) can be an electro-optical phase shifter based on electro-optics, or a thermo-optical phase shifter based on thermo-optics. Since the graphene electro-optical phase shifter without a wave-like periodic structure can significantly reduce the half-wave voltage-length product and optical loss compared to traditional electro-optical phase shifters, therefore, when... Figures 3a to 4 When using an electro-optic phase shifter, a graphene electro-optic phase shifter without a wave-like periodic structure can be selected. As for a thermo-optic phase shifter, one approach is to use a thermo-optic phase shifter with heat-insulating grooves added to both sides of the waveguide or a cantilever beam structure, which can improve the heating efficiency of the heating unit, thereby improving the phase-shifting efficiency of the thermo-optic phase shifter. Another approach is to use a thermo-optic phase shifter comprising a waveguide, at least one grating, and a heating unit thermally coupled to the waveguide. The waveguide can be used to transmit light, and the heating unit can be used to heat at least a portion of the waveguide to change the phase of the light passing through it. The grating is formed on the inner wall or outer surface of the transmission waveguide and can be used to reflect the light in the waveguide at least once, causing the light to pass through the heated waveguide at least twice. Compared to the first approach, this type of thermo-optic phase shifter can repeatedly heat the light without increasing the size of the phase shifter, thereby effectively improving the phase-shifting efficiency.

[0051] As for Figures 3a to 4 The first, second, and third 3dB couplers in the example can be selected from 2×2 multimode interference couplers or / and 2×2 directional couplers, etc. This application does not limit the 3dB couplers.

[0052] exist Figures 1 to 4 In any example of the optical signal processing apparatus, the local oscillator light can be either the local oscillator light split from the local oscillator source by a beam splitter connected before the first coupler 101, or the local oscillator light split from the local oscillator light coupled by the first coupler 101 by a beam splitter connected after the first coupler 101, that is, Figures 1 to 4 Any example optical signal processing apparatus may further include a beam splitter 501 connected to the output of the first coupler 101. The beam splitter 501 can be used to split the local oscillator light output from the first coupler 101 into at least two local oscillator beams, which are then input into at least two mixers 104 respectively. Figures 5a to 5e The optical signal processing device shown; or, Figures 1 to 4 The optical signal processing apparatus of any example may further include a beam splitter 601 connected to the input of the first coupler 101. The beam splitter 601 can be used to split the local oscillator light from the local oscillator source into at least two local oscillator beams, which are then input into at least two first couplers 101 respectively. Figures 6a to 6e The optical signal processing device shown.

[0053] To reduce the coupling loss of devices and / or reduce the power loss of the entire device, in Figures 1 to 4 In any example of an optical signal processing device, the first coupler 101, the second coupler 102, the polarization rotating beam splitter 203, the mixer 104, the balanced detector 105, and the intensity modulator 106 can be integrated on a single chip, or... Figures 5a to 5e In any example of an optical signal processing device, the first coupler 101, the second coupler 102, the polarization rotating beam splitter 203, the mixer 104, the balanced detector 105, the intensity modulator 106, and the beam splitter 501 can be integrated on a single chip.

[0054] Please see Figure 7 This is a schematic flowchart illustrating the optical signal processing method in an embodiment of this application. Figure 7 The example optical signal processing method can be applied to Figures 1 to 6e An optical signal processing apparatus of any example includes a first coupler that outputs local oscillator light, a second coupler that couples a signal light, a polarization rotating beam splitter connected to the output of the second coupler, a mixer connected to the output of the first coupler, and a balanced detector connected to the output of the mixer. It also includes an optical intensity modulator whose input is connected to the output of the polarization rotating beam splitter and whose output is connected to the input of the mixer. Figure 7 The example method mainly includes steps S701 to S704, as explained below:

[0055] Step S701: After coupling one signal beam, output it to the polarization rotating beam splitter.

[0056] It can be done through Figures 1 to 6eIn any example optical signal processing device, the second coupler couples in a signal beam and outputs it to a polarization rotating beam splitter.

[0057] Step S702: The two polarization-consistent signal beams output by the coupled polarization rotating beam splitter are used to obtain a single target signal beam output.

[0058] Optionally, Figure 7 In the example method, the intensity modulator of the corresponding optical signal processing device may include a power divider and an intensity detector. The input of the power divider is connected to the output of the polarization rotating beam splitter, the first output of the power divider is connected to the input of the mixer, and the second output of the power divider is connected to the intensity detector. Coupled with two consistent polarization signal lights output from the polarization rotating beam splitter to obtain a target signal light output, specifically: monitoring the monitoring signal light output from the power divider; and under the monitoring of the intensity detector, coupling the two consistent polarization signal lights output from the polarization rotating beam splitter to obtain a monitoring signal light and a target signal light with an intensity exceeding a first threshold.

[0059] Optionally, Figure 7 In the example method, the power divider of the corresponding optical signal processing device may include two phase shifters connected to the polarization rotating beam splitter and a third 3dB coupler connected to the two phase shifters. Alternatively, the power divider may include a third phase shifter and two 3dB couplers connected to the third phase shifter. Under the monitoring of the light intensity detector, the power divider couples two polarization-consistent signal lights output by the polarization rotating beam splitter to obtain a monitoring signal light and a target signal light with an intensity exceeding a first threshold. This can be achieved by adjusting the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter using the phase shifter until the light intensity detector current corresponding to the monitoring signal light is not greater than a second threshold, the light intensity detector voltage is not greater than a third threshold, or the power divider outputs a target signal light with an intensity exceeding the first threshold.

[0060] Optionally, Figure 7In the example method, when the power divider of the corresponding optical signal processing device includes two phase shifters connected to a polarization rotating beam splitter and a third 3dB coupler connected to the two phase shifters, one end of the first phase shifter is connected to the first output terminal of the polarization rotating beam splitter, and the other end of the first phase shifter is connected to the first input terminal of the third 3dB coupler. One end of the second phase shifter is connected to the second output terminal of the polarization rotating beam splitter, and the other end of the first phase shifter is connected to the second input terminal of the third 3dB coupler. The first output terminal of the third 3dB coupler is connected to a mixer, and the second output terminal of the third 3dB coupler is connected to a light intensity detector. The light intensity detector monitors the monitoring signal light output by the power divider, which can be: the light intensity detector monitors the third 3dB coupler... The monitoring signal light output by the dB coupler is used to obtain the current or voltage value of the light intensity detector corresponding to the monitoring signal light. Under the monitoring of the light intensity detector, the power divider couples two polarization-consistent signal lights output by the polarization rotating beam splitter to obtain a monitoring signal light and a target signal light with an intensity exceeding the first threshold. This can be achieved by adjusting the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter using the first phase shifter and / or the second phase shifter, until the current value of the light intensity detector corresponding to the monitoring signal light output by the third 3dB coupler is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold. The third 3dB coupler outputs the monitoring signal light to the light intensity detector and outputs the target signal light with an intensity exceeding the first threshold to the mixer.

[0061] Optionally, Figure 7 In the example method, when the power divider of the corresponding optical signal processing device includes a third phase shifter and two 3dB couplers connected to the third phase shifter, the two input terminals of the first 3dB coupler are respectively connected to the two output terminals of the polarization rotating beam splitter; the first output terminal of the first 3dB coupler is connected to the input terminal of the third phase shifter; the second output terminal of the first 3dB coupler is connected to the first input terminal of the second 3dB coupler; the output terminal of the third phase shifter is connected to the second input terminal of the second 3dB coupler; the first output terminal of the second 3dB coupler is connected to the mixer; and the second output terminal of the second 3dB coupler is connected to the light intensity detector. The light intensity detector monitors the monitoring signal light output by the power divider, which can be achieved by: the light intensity detector monitoring the monitoring signal light output by the second 3dB coupler to obtain the corresponding light intensity detector current value or voltage value; the power divider, under the monitoring of the light intensity detector, couples two polarization-state consistent signal lights output by the polarization rotating beam splitter to obtain one monitoring signal light and one target signal light with an intensity exceeding a first threshold, which can be achieved by:

[0062] The third phase shifter adjusts the phase of one of the two polarization-consistent signal lights output from the first 3dB coupler until the current value of the light intensity detector corresponding to the monitoring signal light output from the second 3dB coupler is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold; the second 3dB coupler outputs the monitoring signal light to the light intensity detector and outputs a target signal light with an intensity exceeding the first threshold to the mixer.

[0063] Step S703: Mix the target signal light and the local oscillator light output from the first coupler to obtain two beat frequency lights.

[0064] Step S704: Convert the two beat frequency beams into electrical signals and output them.

[0065] Optionally, Figure 7 In the example method, the two polarization-consistent signal lights include two signal lights that are both in the transverse electric mode or two signal lights that are both in the transverse magnetic mode.

[0066] Optionally, Figure 7 In the example method, the corresponding optical signal processing device may further include a beam splitter connected to the output of the first coupler, through which the local oscillator light output from the first coupler can be split into at least two local oscillator lights and then input into at least two mixers respectively.

[0067] Optionally, Figure 7 In the example method, the corresponding optical signal processing device may further include a beam splitter connected to the input end of the first coupler, through which the beam splitter can split the local oscillator light from the local oscillator light source into at least two local oscillator lights, which are then input into at least two first couplers respectively.

[0068] from Figure 7 As can be seen from the example optical signal processing method, each signal light is coupled by the second coupler and passes through the polarization rotation beam splitter. Although two signal lights with the same polarization state are output, only one balanced detector is ultimately required. This means that N signal lights only require N balanced detectors. After passing through these N balanced detectors, only N other devices such as analog-to-digital converters are needed. Therefore, compared with the prior art, which requires 2N balanced detectors and 2N other devices such as analog-to-digital converters for N signal lights, the technical solution of this application not only saves the required system devices, but also reduces the consumption of system resources and the cost of coherent receivers. This is conducive to the promotion and application of equipment such as lidar that require coherent receivers in the fields of autonomous driving, intelligent robots and other technologies.

[0069] This application also provides a coherent receiver, which may include the above-described components. Figures 1 to 6e An optical signal processing device of any example.

[0070] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An optical signal processing device, comprising a first coupler outputting local oscillator light, a second coupler coupling a signal light path, a polarization rotating beam splitter connected to the output terminal of the second coupler, a mixer connected to the output terminal of the first coupler, and a balanced detector connected to the output terminal of the mixer, characterized in that, The device also includes an optical intensity modulator whose input is connected to the two outputs of the polarization rotating beam splitter and whose output is connected to the input of the mixer; The second coupler is used to couple one signal beam and output it to the polarization rotating beam splitter; The light intensity modulator is used to couple two polarization-state consistent signal lights output from the polarization rotating beam splitter to obtain a target signal light, which is then output to the mixer. The mixer is used to mix the target signal light and the local oscillator light output from the first coupler to obtain two beat frequency lights. The balanced detector is used to convert the two beat frequency beams into electrical signals and output them; wherein, each mixer corresponds to one balanced detector; The light intensity modulator includes a power divider and a light intensity detector. The input terminal of the power divider is connected to the output terminal of the polarization rotating beam splitter, the first output terminal of the power divider is connected to the input terminal of the mixer, and the second output terminal of the power divider is connected to the light intensity detector. The light intensity detector is used to monitor the monitoring signal light output by the power divider; The power divider is used to couple two polarization-consistent signal lights output by the polarization rotating beam splitter under the monitoring of the light intensity detector, to obtain a monitoring signal light and a target signal light with an intensity exceeding a first threshold. The power divider includes two phase shifters connected to the polarization rotating beam splitter and a third 3dB coupler connected to the two phase shifters; or, the power divider includes a third phase shifter and two 3dB couplers connected to the third phase shifter. The phase shifter is used to adjust the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter until the current value of the light intensity detector corresponding to the monitoring signal light is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold, or the intensity of the target signal light output by the power divider exceeds the first threshold.

2. The optical signal processing device according to claim 1, characterized in that, When the power divider includes two phase shifters connected to the polarization rotating beam splitter and a third 3dB coupler connected to the two phase shifters, one end of the first phase shifter is connected to the first output terminal of the polarization rotating beam splitter, and the other end of the first phase shifter is connected to the first input terminal of the third 3dB coupler. One end of the second phase shifter is connected to the second output terminal of the polarization rotating beam splitter, and the other end of the first phase shifter is connected to the second input terminal of the third 3dB coupler. The first output terminal of the third 3dB coupler is connected to the mixer, and the second output terminal of the third 3dB coupler is connected to the light intensity detector. The first phase shifter and / or the second phase shifter are used to adjust the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter until the current value of the light intensity detector corresponding to the monitoring signal light output by the third 3dB coupler is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold. The light intensity detector is used to monitor the monitoring signal light output by the third 3dB coupler and obtain the light intensity detector current value or voltage value corresponding to the monitoring signal light. The third 3dB coupler is used to output one monitoring signal light to the light intensity detector and to output one target signal light with an intensity exceeding the first threshold to the mixer.

3. The optical signal processing apparatus according to claim 1, characterized in that, When the power divider includes a third phase shifter and two 3dB couplers connected to the third phase shifter, the two input terminals of the first 3dB coupler are respectively connected to the two output terminals of the polarization rotating beam splitter, the first output terminal of the first 3dB coupler is connected to the input terminal of the third phase shifter, the second output terminal of the first 3dB coupler is connected to the first input terminal of the second 3dB coupler, the output terminal of the third phase shifter is connected to the second input terminal of the second 3dB coupler, the first output terminal of the second 3dB coupler is connected to the mixer, and the second output terminal of the second 3dB coupler is connected to the light intensity detector. The third phase shifter is used to adjust the phase of one of the two polarization-consistent signal lights output by the first 3dB coupler until the current value of the light intensity detector corresponding to the monitoring signal light output by the second 3dB coupler is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold. The light intensity detector is used to monitor the monitoring signal light output by the second 3dB coupler and obtain the light intensity detector current value or voltage value corresponding to the monitoring signal light. The second 3dB coupler is used to output one monitoring signal light to the light intensity detector and to output one target signal light with an intensity exceeding the first threshold to the mixer.

4. The optical signal processing device according to claim 1, characterized in that, The two polarization-consistent signal lights include two signal lights that are both in the transverse electric mode or two signal lights that are both in the transverse magnetic mode.

5. The optical signal processing apparatus according to any one of claims 1 to 4, characterized in that, The device further includes a beam splitter connected to the output end of the first coupler. The beam splitter is used to split the local oscillator light output by the first coupler into at least two local oscillator lights, which are then input into at least two mixers respectively.

6. The optical signal processing apparatus according to any one of claims 1 to 4, characterized in that, The device further includes a beam splitter connected to the input end of the first coupler, the beam splitter being used to split the local oscillator light from the local oscillator source into at least two local oscillator lights, which are then input into at least two of the first couplers respectively.

7. The optical signal processing apparatus according to any one of claims 1 to 5, characterized in that, The first coupler, the second coupler, the polarization rotating beam splitter, the mixer, the balance detector, and the intensity modulator are integrated into a chip, or the first coupler, the second coupler, the polarization rotating beam splitter, the mixer, the balance detector, the intensity modulator, and the beam splitter are integrated into a chip.

8. An optical signal processing method, applied to the optical signal processing apparatus according to any one of claims 1 to 7, characterized in that, The method includes: After a signal light is coupled through the second coupler, it is output to the polarization rotating beam splitter. Two polarization-consistent signal beams output from the polarization rotating beam splitter are coupled by the intensity modulator to obtain a single target signal beam output; the input of the intensity modulator is connected to the two outputs of the polarization rotating beam splitter, and the output is connected to the input of the mixer; The target signal light and the local oscillator light output from the first coupler are mixed by the mixer to obtain two beat frequency lights; The two beat frequency beams are converted into electrical signals by the balanced detector and then output; wherein, each mixer corresponds to one balanced detector; The light intensity modulator includes a power divider and a light intensity detector. The input terminal of the power divider is connected to the output terminal of the polarization rotating beam splitter, the first output terminal of the power divider is connected to the input terminal of the mixer, and the second output terminal of the power divider is connected to the light intensity detector. The light intensity detector is used to monitor the monitoring signal light output by the power divider; The power divider is used to couple two polarization-consistent signal lights output by the polarization rotating beam splitter under the monitoring of the light intensity detector, to obtain a monitoring signal light and a target signal light with an intensity exceeding a first threshold. The power divider includes two phase shifters connected to the polarization rotating beam splitter and a third 3dB coupler connected to the two phase shifters; or, the power divider includes a third phase shifter and two 3dB couplers connected to the third phase shifter. The phase shifter is used to adjust the phase of at least one of the two polarization-consistent signal lights output by the polarization rotating beam splitter until the current value of the light intensity detector corresponding to the monitoring signal light is not greater than the second threshold or the voltage value of the light intensity detector is not greater than the third threshold, or the intensity of the target signal light output by the power divider exceeds the first threshold.

9. A coherent receiver, characterized in that, The coherent receiver includes the optical signal processing apparatus according to any one of claims 1 to 7.

Images