This application relates to the field of coherent optical communications technologies, and in particular, to a coherent optical receiving apparatus and an optical signal demodulation apparatus.
A coherent optical transmission technology is widely used due to a large transmission capacity and a long transmission distance. At a receive end of a coherent optical communications system, local oscillator light and signal light are input to a frequency mixing apparatus for frequency mixing, mixed output light is converted into an electrical signal, and amplitude and phase information of the signal light may be obtained through sampling, analog-to-digital conversion, and digital signal processing, to implement a decoding function.
Currently, a frequency mixing apparatus (for example, a conventional coherent optical frequency mixing unit or a frequency mixer) used in the industry needs to input local oscillator light in a fixed polarization state. Because such a special requirement for a polarization state of local oscillator light cannot be met in a network, for example, a data center network (DCN), the frequency mixing apparatus currently used in the industry cannot work normally. Consequently, the coherent optical transmission technology cannot be applied to a network application scenario, for example, the DCN, and universal adaptability of the coherent optical transmission technology is poor.
To overcome the foregoing disadvantages in the background, embodiments of this application provide a coherent optical receiving apparatus and an optical signal demodulation apparatus, to ensure that when local oscillator light in any polarization state is input to the coherent optical receiving apparatus, the coherent optical receiving apparatus can work normally. Thus, embodiments of this application are provided to implement a frequency mixing function, eliminate a special requirement that a polarization state of the local oscillator light that is input to the coherent optical receiving apparatus needs to be fixed, and improve universal adaptability of a coherent optical transmission technology.
To achieve the foregoing technical objectives, an embodiment of this application provides a coherent optical receiving apparatus, including a polarization beam splitting unit, an optical frequency mixing unit, and a combining unit. The polarization beam splitting unit is connected to an input end of the optical frequency mixing unit, and the combining unit is connected to an output end of the optical frequency mixing unit. The polarization beam splitting unit is configured to receive local oscillator light in any polarization state, and perform polarization state split on the received local oscillator light to obtain first polarized light in a linear polarization state, in order to input the first polarized light to the optical frequency mixing unit. The optical frequency mixing unit is configured to perform frequency mixing on the first polarized light and second polarized light, and output mixed light to the combining unit. The second polarized light is polarized light in a linear polarization state obtained by splitting signal light. The combining unit is configured to combine every two paths of light output by the optical frequency mixing unit into one path for output. Optionally, the combining unit may combine every two paths of mixed optical signals in a same polarization state output by the optical frequency mixing unit into one path.
It can be learned from the foregoing technical solutions that this embodiment of this application has the following advantages: Compared with a conventional frequency mixing apparatus, the polarization beam splitting unit is added to the coherent optical receiving apparatus in this embodiment of this application to perform polarization state split on the local oscillator light in any polarization state, in order to obtain polarized light in a corresponding linear polarized state. Through the foregoing improvement on the conventional frequency mixing apparatus, when the local oscillator light in any polarization state is input to the coherent optical receiving apparatus, the coherent optical receiving apparatus in this embodiment of this application can work normally, in order to implement a frequency mixing function, eliminate a special requirement that a polarization state of the local oscillator light that is input to the coherent optical receiving apparatus needs to be fixed, and improve universal adaptability of a coherent optical transmission technology.
Further, the combining unit is newly designed for the foregoing coherent optical receiving apparatus. The combining unit may combine and output light output by the optical frequency mixing unit. For example, the combining unit combines every two paths of light into one path for output, to reduce output optical paths in the coherent optical receiving apparatus.
In a possible implementation of the first aspect, the optical frequency mixing unit may be a conventional coherent optical frequency mixing unit or a frequency mixer, and the conventional coherent optical frequency mixing unit is obtained by integrating the frequency mixer.
In a possible implementation of the first aspect, if the optical frequency mixing unit is the conventional coherent optical frequency mixing unit, the polarization beam splitting unit may be a polarization beam splitter or a polarization rotator-splitter, and the combining unit is a polarization rotator-combiner.
In a possible implementation of the first aspect, if the optical frequency mixing unit is the frequency mixer, the polarization beam splitting unit may include a power beam splitter and a polarization beam splitter, or the polarization beam splitting unit includes a power beam splitter and a polarization rotator-splitter, and the combining unit is a polarization rotator-combiner.
It should be noted that, the foregoing polarization beam splitting unit and the foregoing combining unit both use a waveguide optical component such as a power beam splitter, a polarization beam splitter, a polarization rotator-splitter, or a polarization rotator-combiner. Compared with a spatial optical component, for example, a lens, a reflection mirror, or a wave plate, the waveguide optical component has a low precision requirement on manufacture, is easy to manufacture and integrate, and facilitates large-scale production.
In a possible implementation of the first aspect, the optical frequency mixing unit includes two conventional coherent optical frequency mixing units, namely, a first conventional coherent optical frequency mixing unit and a second conventional coherent optical frequency mixing unit. The polarization beam splitting unit is a first polarization beam splitter. The combining unit is an array including at least two polarization rotator-combiners, and the array is referred to as a first array. The first polarization beam splitter is configured to split the local oscillator light in any polarization state into first X-polarized light and first Y-polarized light, and respectively input the first X-polarized light and the first Y-polarized light to the first conventional coherent optical frequency mixing unit and the second conventional coherent optical frequency mixing unit after splitting for frequency mixing. The first array is configured to combine light from an xth port in the first conventional coherent optical frequency mixing unit and light from an (x+a/2)th port in the second conventional coherent optical frequency mixing unit into one path, and combine light from an (x+a/2)th port in the first conventional coherent optical frequency mixing unit and light from an xth port in the second conventional coherent optical frequency mixing unit into one path, where x is a positive integer less than or equal to (a/2), where a is a total quantity of polarization rotator-combiners, where a value of a is an even number greater than or equal to 0, and where a total quantity of ports in the first conventional coherent optical frequency mixing unit and a total quantity of ports in the second conventional coherent optical frequency mixing unit are both equal to a.
For example, a total quantity of ports in the first conventional coherent optical frequency mixing unit and a total quantity of ports in the second conventional coherent optical frequency mixing unit are 8. In other words, a is equal to 8, and a value of x is 1, 2, 3 or 4. In this case, the first array is an array including eight polarization rotator-combiners. A manner of combining optical paths is as follows: A first polarization rotator-combiner combines light from a port 1 in the first conventional coherent optical frequency mixing unit and light from a port 5 in the second conventional coherent optical frequency mixing unit into one path. A second polarization rotator-combiner combines light from a port 2 in the first conventional coherent optical frequency mixing unit and light from a port 6 in the second conventional coherent optical frequency mixing unit into one path. A third polarization rotator-combiner combines light from a port 3 in the first conventional coherent optical frequency mixing unit and light from a port 7 in the second conventional coherent optical frequency mixing unit into one path. A fourth polarization rotator-combiner combines light from a port 4 in the first conventional coherent optical frequency mixing unit and light from a port 8 in the second conventional coherent optical frequency mixing unit into one path. A fifth polarization rotator-combiner combines light from a port 5 in the first conventional coherent optical frequency mixing unit and light from a port 1 in the second conventional coherent optical frequency mixing unit into one path. A sixth polarization rotator-combiner combines light from a port 6 in the first conventional coherent optical frequency mixing unit and light from a port 2 in the second conventional coherent optical frequency mixing unit into one path. A seventh polarization rotator-combiner combines light from a port 7 in the first conventional coherent optical frequency mixing unit and light from a port 3 in the second conventional coherent optical frequency mixing unit into one path. An eighth polarization rotator-combiner combines light from a port 8 in the first conventional coherent optical frequency mixing unit and light from a port 4 in the second conventional coherent optical frequency mixing unit into one path. Therefore, output optical paths in the coherent optical receiving apparatus changes from eight optical paths into four output optical paths in the conventional coherent optical frequency mixing unit.
It should be noted that the first polarization beam splitter in this implementation may be replaced with a first polarization rotator-splitter, and details are not described herein again.
In a possible implementation of the first aspect, the optical frequency mixing unit includes a first frequency mixer, a second frequency mixer, a third frequency mixer, and a fourth frequency mixer. The combining unit is an array including at least two polarization rotator-combiners, and the array is referred to as a second array. The second array is configured to combine light from a yth port in the first frequency mixer and light from a yth port in the third frequency mixer into one path, and combine light from a yth port in the second frequency mixer and light from a yth port in the fourth frequency mixer into one path, where y is a port number of the frequency mixer, where a value of y is a positive integer less than or equal to b, where b is a total quantity of ports in the frequency mixer, and where a value of b is an even number greater than or equal to 0. In other words, the second array is configured to combine light corresponding to ports that have a same port number and that are in the first frequency mixer and the third frequency mixer, and combine light from ports that have a same port number and that are in the second frequency mixer and the fourth frequency mixer.
For example, a total quantity of ports in the frequency mixer b is equal to 4, and the combining unit is a second array including eight polarization rotator-combiners. A first polarization rotator-combiner combines light from a port 1 in the first frequency mixer and light from a port 1 in the third frequency mixer into one path. A second polarization rotator-combiner combines light from a port 2 in the first frequency mixer and light from a port 2 in the third frequency mixer into one path. A third polarization rotator-combiner combines light from a port 3 in the first frequency mixer and light from a port 3 in the third frequency mixer into one path. A fourth polarization rotator-combiner combines light from a port 4 in the first frequency mixer and light from a port 4 in the third frequency mixer into one path. A fifth polarization rotator-combiner combines light from a port 1 in the second frequency mixer and light from a port 1 in the fourth frequency mixer into one path. A sixth polarization rotator-combiner combines light from a port 2 in the second frequency mixer and light from a port 2 in the fourth frequency mixer into one path. A seventh polarization rotator-combiner combines light from a port 3 in the second frequency mixer and light from a port 3 in the fourth frequency mixer into one path. An eighth polarization rotator-combiner combines light from a port 4 in the second frequency mixer and light from a port 4 in the fourth frequency mixer into one path.
In the foregoing implementation that the optical frequency mixing unit includes the first frequency mixer, the second frequency mixer, the third frequency mixer, and the fourth frequency mixer, and the combining unit is the array including the at least two polarization rotator-combiners, the polarization beam splitting unit may be implemented in the following two manners.
In a first implementation, the polarization beam splitting unit includes a polarization beam splitter (namely, a second polarization beam splitter), and two power beam splitters (namely, a first power beam splitter and a second power beam splitter). The second polarization beam splitter is configured to split the local oscillator light in any polarization state into second X-polarized light and second Y-polarized light, and respectively input the second X-polarized light and the second Y-polarized light to the first power beam splitter and the second power beam splitter. Further, the first power beam splitter and the second power beam splitter respectively split the second X-polarized light and the second Y-polarized light into two parts and input the four parts to four frequency mixers. In other words, the first power beam splitter splits the second X-polarized light into two parts and respectively inputs the two parts to the first frequency mixer and the second frequency mixer, and the second power beam splitter the second Y-polarized light into two parts, and respectively input the two parts to the third frequency mixer and the fourth frequency mixer.
In a second implementation, the polarization beam splitting unit includes a power beam splitter (namely, a third power beam splitter), and two polarization beam splitters (namely, a third polarization beam splitter and a fourth polarization beam splitter). The third power beam splitter is configured to split the local oscillator light in any polarization state into two parts, and respectively input the two parts to the third polarization beam splitter and the fourth polarization beam splitter. The third polarization beam splitter is configured to split one part of the input local oscillator light into third X-polarized light and third Y-polarized light, and respectively input the third X-polarized light and the third Y-polarized light to the first frequency mixer and the second frequency mixer. The fourth polarization beam splitter is configured to split the other part of the input local oscillator light into fourth X-polarized light and fourth Y-polarized light, and respectively input the fourth X-polarized light and the fourth Y-polarized light to the third frequency mixer and the fourth frequency mixer.
In a possible implementation of the first aspect, the polarization beam splitting unit further includes at least one of the following: a phase shifter and a half-wave plate. The phase shifter is configured to adjust a phase of light, before the light is input to a local oscillator light port in the first frequency mixer, the second frequency mixer, the third frequency mixer, or the fourth frequency mixer. The half-wave plate is configured to rotate a polarization state of polarized light obtained by splitting the local oscillator light.
In a possible implementation of the first aspect, the coherent optical receiving apparatus may further include at least one of the following: an optical anti-reflective coating, an optical waveguide, a lens, an optical monitor, or a photoelectric detector.
According to a second aspect, an embodiment of this application further provides an optical signal demodulation apparatus. The optical signal demodulation apparatus includes the coherent optical receiving apparatus in the first aspect and any one of the implementations of the first aspect.
In a possible implementation of the second aspect, the optical signal demodulation apparatus further includes at least one of the following: a direct current filter, a trans-impedance amplifier, an analog-to-digital converter, or a digital signal processor.
The following describes embodiments of this application with reference to the accompanying drawings. It is clear that the described embodiments are merely a part rather than all of the embodiments of this application. A person of ordinary skill in the art may learn that as a technology evolves and a new scenario emerges, technical solutions provided in the embodiments of this application are also applicable to a similar technical problem.
The embodiments of this application provide a coherent optical receiving apparatus and an optical signal demodulation apparatus, to eliminate a special requirement that a polarization state of local oscillator light that is input to the coherent optical receiving apparatus needs to be fixed, and improve universal adaptability of a coherent optical transmission technology.
The term “and/or” appeared in this application describes only an association relationship for describing associated objects and represents that three relationships may exist. For example, A and/or B may represent the following three cases: Only A exists, both A and B exist, and only B exists. In addition, the character “/” in this application generally indicates an “or” relationship between the associated objects.
In the specification, claims, and the accompanying drawings of this application, the terms “first”, “second”, and the like are intended to distinguish similar objects but do not necessarily indicate a specific order or sequence. It should be understood that data used in such a way is interchangeable in a proper circumstance, such that the embodiments described herein can be implemented in an order other than the order illustrated or described herein. In addition, the terms “include”, “contain” and any other variants mean to cover the non-exclusive inclusion, for example, a process, method, system, product, or device that includes a list of steps or modules is not necessarily limited to those steps or modules, but may include other steps or modules not expressly listed or inherent to such a process, method, system, product, or device. Naming or numbering of steps in this application does not mean that the steps in the method procedures need to be performed in a time/logical order indicated by the naming or numbering. An execution order of the steps in the procedures that have been named or numbered can be changed based on a technical objective to be achieved, as long as same or similar technical effects can be achieved. Division into modules in this application is logical division and may be another division in an actual implementation. For example, a plurality of modules may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces. The indirect couplings or communication connections between the modules may be implemented in electronic or other similar forms. This is not limited in this application. In addition, modules or sub-modules described as separate components may be or may not be physically separated, may be or may not be physical modules, or may be distributed into a plurality of circuit modules. Objectives of the solutions of this application may be achieved by selecting some or all of the modules based on an actual requirement.
For ease of understanding the coherent optical receiving apparatus provided in the embodiments of this application, the following describes in detail the coherent optical receiving apparatus in the embodiments of this application with reference to example embodiments. Details are as follows.
As shown in
In an implementation, the optical frequency mixing unit 102 may be a conventional coherent optical frequency mixing unit or a frequency mixer, and the conventional coherent optical frequency mixing unit is obtained by integrating the frequency mixer. The following separately describes in detail structures of the conventional coherent optical frequency mixing unit and the frequency mixer.
As shown in
It should be noted that both a polarization state X and the polarization state Y are linear polarization states. The local oscillator light in the fixed polarization state is substantially polarized light, in other words, the local oscillator light in the polarization state Y is equivalent to Y-polarized light, and local oscillator light in the polarization state X is equivalent to X-polarized light. That the Y-polarized light and the X-polarized light are respectively referred to as the local oscillator light in the polarization state Y and the local oscillator light in the polarization state X is intended to be distinguished from signal light. The coupling lens is merely a common lens, and is referred to as a coupling lens because the lens is used for optical coupling herein. A meaning of the coupling lens mentioned below is similar to the coupling lens herein, and details are not described again below.
It should be further noted that the polarization beam splitter may be a polarization beam splitter (PBS). The power beam splitter is a functional description to distinguish the power beam splitter from the polarization beam splitter, and refers to a beam splitter (BS) that directly splits light into two parts without changing a polarization state of the light. A structure of the frequency mixer in
As shown in
In an implementation, the optical frequency mixing unit includes two conventional coherent optical frequency mixing units, namely, a first conventional coherent optical frequency mixing unit and a second conventional coherent optical frequency mixing unit. The combining unit 103 may be an array including at least two polarization rotator-combiners, and the array is referred to as a first array. The first array is configured to combine light from an xth port in the first conventional coherent optical frequency mixing unit and light from an (x+a/2)th port in the second conventional coherent optical frequency mixing unit into one path, and combine light from an (x+a/2)th port in the first conventional coherent optical frequency mixing unit and light from an xth port in the second conventional coherent optical frequency mixing unit into one path, where x is a positive integer less than or equal to (a/2), where a is a total quantity of polarization rotator-combiners, where a value of a is an even number greater than or equal to 0, and where a total quantity of ports in the first conventional coherent optical frequency mixing unit and a total quantity of ports in the second conventional coherent optical frequency mixing unit are both equal to a. For descriptions of this implementation, refer to the following related descriptions in the embodiment corresponding to
In an implementation, the optical frequency mixing unit includes a first frequency mixer, a second frequency mixer, a third frequency mixer, and a fourth frequency mixer. The combining unit may be an array including at least two polarization rotator-combiners, and the array is referred to as a second array. The second array is configured to combine light from a yth port in the first frequency mixer and light from a yth port in the third frequency mixer into one path, and combine light from a yth port in the second frequency mixer and light from a yth port in the fourth frequency mixer into one path, where y is a port number of the frequency mixer, where a value of y is a positive integer less than or equal to b, where b is a total quantity of ports in the frequency mixer, and where a value of b is an even number greater than or equal to 0. In other words, the second array is configured to combine light corresponding to ports that have a same port number and that are in the first frequency mixer and the third frequency mixer. For descriptions of this implementation, refer to the following related descriptions in the embodiment corresponding to
It can be learned from the foregoing implementations that the optical frequency mixing unit in the coherent optical receiving apparatus provided in the embodiments of this application may be implemented using the following two implementations. The following separately describes the foregoing implementations.
In a first implementation, the optical frequency mixing unit includes conventional coherent optical frequency mixing units. In the first implementation, the optical frequency mixing unit may include two or more conventional coherent optical frequency mixing units. The conventional coherent optical frequency mixing unit may use the conventional 2×8 coherent optical frequency mixing unit with two input optical ports and eight output optical ports shown in
The following describes in detail the optical frequency mixing unit provided in the embodiments of this application using an example in which an optical frequency mixing unit including two conventional 2×8 coherent optical frequency mixing units.
As shown in
In
The eight polarization rotator-combiners in the first array 407 are configured to couple output of the first conventional 2×8 coherent optical frequency mixing unit 405 and output of the second conventional 2×8 coherent optical frequency mixing unit 406, to reduce a quantity of output optical paths.
For example, as shown in
Optionally, as shown in
It should be understood that the PD in the detector array 408 may convert an optical signal into an electrical signal, to perform subsequent operations such as sampling, analog-to-digital conversion, and digital signal processing on the electrical signal as described in the background, in order to implement a decoding function. The coupling lens 401 may implement a coupling connection between an optical signal (signal light and local oscillator light) transmitter and the coherent optical receiving apparatus described in
The waveguide optical component means that optical components are connected to each other using a waveguide, to transmit an optical signal. The waveguide optical component is different from a spatial optical component, for example, a lens, a reflection mirror, or a wave plate. As the name implies, the spatial optical component is an optical component in which an optical signal is propagated in space instead of in a waveguide. Compared with the spatial optical component, in this embodiment of this application, the coherent optical receiving apparatus including the waveguide optical component has a low precision requirement for manufacture, is easy to manufacture and integrate, and facilitates large-scale production.
A total of 16 output waveguides of the first conventional 2×8 coherent optical frequency mixing unit 405 and the second conventional 2×8 coherent optical frequency mixing unit 406 are polarization-maintaining waveguides. The polarization-maintaining waveguide is briefly referred to as a polarization-maintaining fiber (PMF). It should be noted that the waveguide in this embodiment of this application may be made of a material, for example, silicon, germanium, silicon dioxide, silicon nitride, or III-V. This is not limited in this application.
Signal light in any polarization state is output from an optical fiber, and enters the polarization-maintaining optical waveguide through the coupling lens 401. The power beam splitter 403 splits the signal light into two parts, and the two parts respectively enter the first conventional 2×8 coherent optical frequency mixing unit 405 and the second conventional 2×8 coherent optical frequency mixing unit 406. Local oscillator light in any polarization state is output from an optical fiber, and enters the polarization-maintaining optical waveguide through the coupling lens 401. The polarization beam splitter or the polarization rotator-splitter 404 splits the local oscillator light into a polarization state X and a polarization state Y. Light in the polarization state X and light in the polarization state Y enters local oscillator light ports in the first conventional 2×8 coherent optical frequency mixing unit 405 and the second conventional 2×8 coherent optical frequency mixing unit 406.
Optionally, in this embodiment of this application, a typical value of a split ratio of the power beam splitter 403 is 50:50. Polarization-dependent losses of each of the polarization beam splitter, the polarization rotator-splitter, and the polarization rotator-combiner are less than 3 decibels (dB).
Compared with
Similarly, the combining unit 103 in
In a second implementation, the optical frequency mixing unit directly includes frequency mixers.
In the second implementation, the optical frequency mixing unit may directly include two or more frequency mixers, and the frequency mixer may be the 2×4 frequency mixer shown in
The following describes in detail the coherent optical receiving apparatus provided in the embodiments of this application using an example of four 2×4 frequency mixers.
As shown in
The second array 511 is configured to combine light from a yth port in the first frequency mixer 507 and light from a yth port in the third frequency mixer 508 into one path, and combine light from a yth port in the second frequency mixer 509 and light from a yth port in the fourth frequency mixer 510 into one path, where y is a port number of the frequency mixer, where a value of y is a positive integer less than or equal to b, where b is a total quantity of ports in the frequency mixer, and where a value of b is an even number greater than or equal to 0. In other words, the second array 511 is configured to combine light from ports that have a same port number and that are in the first frequency mixer 507 and the third frequency mixer 508, and combine light from ports that have a same port number and that are in the second frequency mixer 509 and the fourth frequency mixer 510.
For example, in
Similar to the foregoing embodiment corresponding to
In this embodiment of this application, obtaining a plurality of paths of polarized light from local oscillator light in any polarization state may be implemented by first performing polarization state split, and then performing beam splitting processing, which corresponds to the first implementation described in the foregoing embodiments. Alternatively, it may be implemented by first performing beam splitting processing, and then performing polarization state split, which corresponds to the second implementation described in the foregoing embodiments. The following separately describes the two implementations. In a first implementation, polarization state split is first performed on local oscillator light, and then beam splitting processing is performed.
For example, the polarization beam splitting unit 101 in
In this implementation, a manner of processing local oscillator light may be as follows: The polarization beam splitter 503 splits the local oscillator light (denoted as LO) in any polarization state into second X-polarized light and second Y-polarized light, and respectively inputs the second X-polarized light and the second Y-polarized light to the power beam splitter 504 and the power beam splitter 505. The second X-polarized light and the second Y-polarized light are respectively marked as LOx and LOy. The power beam splitter 504 splits the second X-polarized light LOx into two beams of polarized light, namely, LOx1 and LOx2, and respectively inputs the two beams of polarized light to local oscillator light ports in the third frequency mixer 508 and the fourth frequency mixer 510. Similarly, the power beam splitter 505 splits the second Y-polarized light LOy into two beams of polarized light, namely, LOy1 and LOy2, and respectively inputs the two beams of polarized light to local oscillator light ports in the first frequency mixer 507 and the second frequency mixer 509.
Corresponding to the foregoing manner of processing the local oscillator light, the polarization beam splitting unit 101 in
In a second implementation, local oscillator light is split first, and then a polarization state is split.
In the foregoing first implementation, local oscillator light is processed in the manner of first splitting a polarization state and then splitting the light. However, signal light is processed in the manner of first splitting the light and then splitting a polarization state. In this embodiment of this application, a polarization state of local oscillator light does not need to be a linear polarization state. Therefore, the manner of processing signal light is also applicable to local oscillator light processing. In other words, in this embodiment of this application, a local oscillator light input port and a signal light input port are equivalent and may be interchanged.
For example, in
Based on the foregoing two manners of processing local oscillator light and signal light, a structure of another polarization beam splitting unit that may be further obtained fall within the protection scope of the embodiments of this application. This is not limited in this application.
Optionally, in an implementation, the polarization beam splitting unit may further include a phase shifter 506. The phase shifter 506 is configured to adjust a phase of one path of polarized light obtained by splitting local oscillator light, and a phase shift value is not equal to N times of 2π, and N=0, 1, 2, 3, . . . .
Optionally, in an implementation, the coherent optical receiving apparatus may further include at least one of a coupling lens 501, an optical anti-reflective coating 502, or a photoelectric detector array 512. Functions and descriptions of the coupling lens 501, the optical anti-reflective coating 502, and the photoelectric detector array 512 in this embodiment of this application are similar to functions and descriptions of the coupling lens 401, the optical anti-reflective coating 402, and the photoelectric detector array 412 in the embodiment corresponding to
A difference between the coherent optical receiving apparatus shown in
The HWP 616 is configured to rotate polarization states of beams B1 to B3 (namely, the polarized light Sy1, LOy2, and Sx2) by 90 degrees, and the six newly-added coupling lenses are configured to output the six beams of light from output ports in a spatial optical component to input ports in a waveguide optical component. It should be understood that, because the half-wave plate 616 is a spatial optical component, the half-wave plate 616 is different from the coherent optical receiving apparatus corresponding to
A structure shown in
As shown in
The first PD 704 and the second PD 705 are configured to: respectively perform photoelectric detection on optical power of X-polarized light LOx and Y-polarized light LOy that are obtained after the PBS/PRS 701 splits local oscillator light (denoted as LO in
The control unit 708 is configured to perform automatic power control based on a difference between the optical power values detected by the first PD 704 and the second PD 705, to control power values of the X-polarized light LOx and the Y-polarized light LOy.
The first optical monitoring unit 702 is configured to control power of the X-polarized light within a power range that is of the X-polarized light LOx and that is fed back by the control unit 708.
The second optical monitoring unit 703 is configured to control power of the Y-polarized light within a power range that is of the Y-polarized light LOy and that is fed back by the control unit 708.
The first driver 706 and the second driver 707 are respectively configured to drive the second optical monitoring unit 703 and the first optical monitoring unit 702.
An embodiment of this application further provides an optical signal demodulation apparatus based on a coherent optical receiving apparatus. A schematic diagram of the optical signal demodulation apparatus is shown in
The coherent optical receiving apparatus in
Based on the optical signal demodulation apparatus of the coherent optical receiving apparatus in this embodiment of this application, compared with a conventional receiving apparatus, the coherent optical receiving apparatus in this embodiment of this application outputs fewer signals, such that quantities of the differential operator, the direct current filter, the trans-impedance amplifier, and the analog-to-digital converter in the optical signal demodulation apparatus are reduced by half during usage, thereby reducing device costs of the optical signal demodulation apparatus.
It should be noted that, in this application, because polarization states of signal light and local oscillator light that are input into the coherent optical receiving apparatus are both random, the coherent optical receiving apparatus in the embodiments of this application is a polarization-independent optical receiving apparatus. It should be further noted that the optical signal demodulation apparatus shown in
For a structure and a function of the coherent optical receiving apparatus shown in
The coherent optical receiving apparatus and the optical signal demodulation apparatus provided in the embodiments of this application are described in detail above. The principle and implementations of this application are described in this specification using examples. The descriptions about the embodiments are merely provided to help understand the method and core ideas of this application. In addition, a person of ordinary skill in the art can make changes to this application in terms of the implementations and application scopes according to the ideas of this application. In conclusion, the content of the specification shall not be construed as a limit to this application.
Number | Date | Country | Kind |
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201910305380.2 | Apr 2019 | CN | national |
This application is a continuation of International Patent Application No. PCT/CN2019/122376, filed on Dec. 2, 2019, which claims priority to Chinese Patent Application No. 201910305380.2, filed on Apr. 16, 2019. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties.
Number | Date | Country | |
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Parent | PCT/CN2019/122376 | Dec 2019 | US |
Child | 17397260 | US |