Expanded bandwidth heterodyne coherent receiving mechanism without optical filter

Abstract

The utility model relates to the technical field of optical communication, in particular to an expanded bandwidth heterodyne coherent receiving mechanism without an optical filter. Comprising a first optical splitter module and a second optical splitter module, the first optical splitter module is connected with a first polarization beam splitter module and a second polarization beam splitter module, the second optical splitter module is connected with a third optical splitter module and a fourth optical splitter module, and an optical delay line module is arranged between the output end of the second optical splitter module and the fourth optical splitter module. The output ends of the first polarization beam splitter module, the second polarization beam splitter module, the third optical splitter module and the fourth optical splitter module are all connected with an optical coupler module, and the optical coupler module is connected with an electric signal recombination module through a balanced photoelectric detector module. The receiving mechanism provided by the utility model not only saves an optical filter and a 90-degree optical mixer, but also can realize heterodyne coherent detection with low hardware complexity and an internal difference detection coherent receiver with spectral efficiency approaching a standard by only needing half of signal optical bandwidth.

Description

Technical Field

[0001] The utility model relates to the technical field of optical communication, in particular to an extended bandwidth heterodyne coherent receiving mechanism without an optical filter. Background Art

[0002] Through the linear beat frequency of the signal light and the local oscillator light, the coherent optical receiver can simultaneously detect the in-phase and orthogonal signal components of the dual-polarization light field, achieving optical and electrical spectrum efficiencies four times that of the intensity modulation direct detection scheme. At the same time, since the signal is linearly mapped from the optical domain to the electrical domain, it is possible to effectively compensate for channel impairments such as fiber dispersion, random polarization rotation, polarization mode dispersion, and Kerr effect through digital domain signal processing, supporting backbone networks and transoceanic transmission. For transmission scenarios such as metropolitan area networks, core networks, and power communication private networks with a length of hundreds of kilometers, the cost of optical fiber is relatively low, so it is necessary to simplify the hardware complexity of coherent optical receivers.

[0003] According to the relative frequency relationship between the signal light and the local oscillator light, coherent optical receivers can be divided into two categories: intradyne detection and heterodyne detection. For intradyne detection, a dual-polarization 90-degree optical mixer and four pairs of balanced photodetectors are required to complete the reception, among which the implementation of the 90-degree optical mixer is relatively complex. Since the local oscillator light frequency is close to the center of the signal light frequency, the electrical bandwidth requirement of the balanced photodetector is about half of the signal light bandwidth. In contrast, heterodyne detection only requires a dual-polarization 2×2 optical coupler and two pairs of balanced photodetectors to complete the reception, without the need for a 90-degree optical mixer, which can reduce complexity. However, since the local oscillator light frequency is outside the spectrum range of the signal light, the electrical bandwidth requirement of the balanced photodetector is greater than or equal to the signal light bandwidth, which is twice that of intradyne detection.

[0004] In order to reduce the electrical bandwidth requirements of heterodyne detection receivers, there is a solution to design a pair of optical filters to perform spectrum segmentation on the signal light or local oscillator light, and then perform spectrum synthesis in the electrical domain / digital domain. However, the structure of the optical filter with steep edges is relatively complex. Therefore, how to reduce the electrical bandwidth requirements of heterodyne detection coherent receivers without using complex structures such as optical filters and maintaining the advantages of the simple heterodyne detection coherent receiving mechanism is a problem to be solved. Utility Model Content

[0005] Problem to be solved: How to reduce the electrical bandwidth requirement of heterodyne detection coherent receiver without using complex structures such as optical filters

[0006] In order to achieve the above-mentioned purpose, the utility model provides the following technical solutions: spectrum decomposition and recombination are realized through an optical delay line module, that is, an extended bandwidth heterodyne coherent receiving mechanism without an optical filter is provided. It includes a first optical splitter module and a second optical splitter module, the output end of the first optical splitter module is respectively connected to a first polarization beam splitter module and a second polarization beam splitter module, the output end of the second optical splitter module is respectively connected to a third optical splitter module and a fourth optical splitter module, an optical delay line module is arranged between the output end of the second optical splitter module and the fourth optical splitter module, the output ends of the first polarization beam splitter module, the second polarization beam splitter module, the third optical splitter module and the fourth optical splitter module are all connected to an optical coupler module, and the optical coupler module is connected to an electrical signal recombination module through a balanced photodetector module.

[0007] Preferably, there are a plurality of optical coupler modules and a plurality of balanced photodetector modules, and the plurality of optical coupler modules correspond one to one with the plurality of balanced photodetector modules.

[0008] Preferably, the plurality of optical coupler modules are four optical coupler modules, the plurality of balanced photodetector modules are four balanced photodetector modules, and the four optical coupler modules are connected to the four balanced photodetector modules in a one-to-one correspondence.

[0009] Compared with the prior art, the utility model provides an extended bandwidth heterodyne coherent receiving mechanism without an optical filter, which has the following beneficial effects: reducing the electrical bandwidth requirements of the heterodyne detection coherent receiver and maintaining the advantage of its simple structure. Therefore, the utility model provides an extended bandwidth heterodyne detection coherent receiving mechanism without an optical filter, which includes four optical splitters, two polarization beam splitters, an optical delay line module, four optical couplers, four pairs of balanced photodetectors, and an electrical signal decomposition and recombination module. The optical delay line module is used to adjust the relative phase of the local oscillator light of the dual-frequency component, and the in-phase and anti-phase superposition of the left and right spectral components of the signal is achieved in the photoelectric conversion process, and finally the signal recovery is completed based on the electrical signal recombination module.

[0010] The utility model fully combines the low complexity advantage of heterodyne detection and the low bandwidth requirement advantage of intradyne detection, and provides an extended bandwidth heterodyne coherent receiving mechanism that does not require an optical filter. The linear superposition and decomposition reconstruction of the left and right spectral components of the signal are realized through the optical delay line module. Only half of the signal optical bandwidth is required to complete heterodyne detection, providing a potential solution for application scenarios such as metropolitan area networks, core networks, and power communication networks. This receiving mechanism not only saves optical filters and 90-degree optical mixers, but also only half of the signal optical bandwidth is required to achieve low hardware complexity heterodyne coherent detection, and the spectrum efficiency is close to that of a standard intradyne detection coherent receiver. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1This is a system structure diagram of the utility model. DETAILED DESCRIPTION

[0012] The technical scheme in the embodiment of the present invention will be described below in conjunction with the accompanying drawings in the embodiment of the present invention:

[0013] like Figure 1 As shown, an extended bandwidth heterodyne coherent receiving mechanism without an optical filter comprises a first optical splitter module and a second optical splitter module. The first optical splitter module mainly functions to receive a signal light input and then split the input signal light into two beams. Two output ends of the first optical splitter module are respectively connected to a first polarization beam splitter module and a second polarization beam splitter module.

[0014] The main function of the second optical splitter module is to receive the local oscillator light input. The input local oscillator light contains dual frequency components, and the interval between the two frequency components is greater than the signal light bandwidth. The second optical splitter module divides the input local oscillator light into two beams. The two output ends of the second optical splitter module are respectively connected to the third optical splitter module and the optical delay line module. The delay amount of the optical delay line module is equal to half of the reciprocal of the interval between the two frequency components of the local oscillator light. The output end of the optical delay line module is connected to the fourth optical splitter module; the input end of the first polarization beam splitter module is connected to the first optical splitter module, which is used to split the input signal light into a first X-polarization signal light and a first Y-polarized signal light; an input end of the third optical splitter module is connected to the second optical splitter module, and is used to split the input local oscillation light into a first local oscillation light and a second local oscillation light; an input end of the second polarization beam splitter module is connected to the first optical splitter module, and is used to split the input signal light into a second X-polarized signal light and a second Y-polarized signal light; an input end of the optical delay line module is connected to the second optical splitter module, and is used to delay the input local oscillation light, and transmit it to the fourth optical splitter module after the delay; an input end of the fourth optical splitter module is connected to an output end of the optical delay line module, and is used to split the input local oscillation light into a third local oscillation light and a fourth local oscillation light;

[0015] The electrical domain / digital domain includes four optical coupler modules and four balanced photodetector modules. The four optical coupler modules and the four balanced photodetector modules are connected one by one. The four balanced photodetector modules transmit their respective output electrical signals to the electrical signal recombination module. After receiving the electrical signals, the electrical signal recombination module outputs an X-polarization digital signal and a Y-polarization digital signal.

[0016] The four optical couplers are respectively a first optical coupler module, a second optical coupler module, a third optical coupler module and a fourth optical coupler module; the first optical coupler module is connected to the first polarization beam splitter module and the third optical splitter module, and is used to achieve mixing of the first X polarized light and the first local oscillation light; the second optical coupler module is connected to the first polarization beam splitter module and the third optical splitter module, and is used to achieve mixing of the first Y polarized light and the second local oscillation light; the third optical coupler module is connected to the second polarization beam splitter module and the fourth optical splitter module, and is used to achieve mixing of the second X polarized light and the third local oscillation light; the fourth optical coupler module is connected to the second polarization beam splitter module and the fourth optical splitter module, and is used to achieve mixing of the second Y polarized light and the fourth local oscillation light.

[0017] The four balanced photodetectors include a first balanced photodetector module, a second balanced photodetector module, a third balanced photodetector module and a fourth balanced photodetector module; the electrical bandwidths of the first, second, third and fourth balanced photodetector modules are only half of the signal light bandwidth; the first balanced photodetector module is connected to the first optical coupler module for converting the input into a first electrical signal; the second balanced photodetector module is connected to the second optical coupler module for converting the input into a second electrical signal; the third balanced photodetector module is connected to the third optical coupler module for converting the input into a third electrical signal; the fourth balanced photodetector module is connected to the fourth optical coupler module for converting the input into a fourth electrical signal;

[0018] The input end of the electrical signal recombination module is connected to the first balanced photodetector module, the second balanced photodetector module, the third balanced photodetector module and the fourth balanced photodetector module, and is used to convert the input first electrical signal, the second electrical signal, the third electrical signal and the fourth electrical signal into an X-polarized digital signal and a Y-polarized digital signal.

[0019] The above embodiments are only some embodiments of the utility model, not all embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

Claims

1. An extended bandwidth heterodyne coherent receiving mechanism without an optical filter, comprising a first optical splitter module and a second optical splitter module, wherein the output end of the first optical splitter module is respectively connected to the first polarization beam splitter module and the second polarization beam splitter module, and the output end of the second optical splitter module is respectively connected to the third optical splitter module and the fourth optical splitter module, characterized in that: An optical delay line module is arranged between the output end of the second splitter module and the fourth splitter module, and the output ends of the first polarization beam splitter module, the second polarization beam splitter module, the third splitter module and the fourth splitter module are all connected to optical coupler modules, and the optical coupler module is connected to the electrical signal recombination module through a balanced photodetector module.

2. The extended bandwidth heterodyne coherent receiving mechanism without an optical filter as claimed in claim 1, characterized in that: There are a plurality of optical coupler modules and a plurality of balanced photoelectric detector modules, and the plurality of optical coupler modules correspond one to one with the plurality of balanced photoelectric detector modules.

3. The extended bandwidth heterodyne coherent receiving mechanism without an optical filter as claimed in claim 2, characterized in that: The plurality of optical coupler modules are four optical coupler modules, the plurality of balanced photodetector modules are four balanced photodetector modules, and the four optical coupler modules are connected to the four balanced photodetector modules in a one-to-one correspondence.

Images