CN111865421B

CN111865421B - Optical fiber phase compensator of high-precision optical fiber interferometer

Info

Publication number: CN111865421B
Application number: CN202010777055.9A
Authority: CN
Inventors: 岳耀笠; 张首刚; 高帅和; 胡珍源; 刘鹏飞; 农定鹏; 张昕; 王航
Original assignee: CETC 34 Research Institute; National Time Service Center of CAS
Current assignee: CETC 34 Research Institute; National Time Service Center of CAS
Priority date: 2020-08-05
Filing date: 2020-08-05
Publication date: 2021-09-07
Anticipated expiration: 2040-08-05
Also published as: CN111865421A

Abstract

The invention discloses an optical fiber phase compensator of a high-precision optical fiber interferometer, which adopts an equal-length optical fiber substitution method, namely, the length of a non-common optical fiber segment in a measuring arm of the optical fiber interferometer at an input end or an output end is consistent with the length of a blind area optical fiber, so that the phase drift of the blind area optical fiber is equivalently measured, the phase drift detection error minimization of service optical signals transmitted in an optical fiber link is realized, and higher phase compensation precision is obtained. Experiments show that when the length error of the equal-length substituted optical fiber is 1cm, the long-term (24h) system phase drift detection error caused by the equal-length substituted optical fiber is less than 10fs, and the short-term (1s) system phase drift detection error can be ignored.

Description

Optical fiber phase compensator of high-precision optical fiber interferometer

Technical Field

The invention relates to the technical field of optical fiber phase-stabilizing transmission, in particular to an optical fiber phase compensator of a high-precision optical fiber interferometer.

Background

The optical fiber phase compensator is an optical fiber phase stabilization transmission device applied to optical fiber transmission radio frequency coherent signals, and is characterized in that an optical fiber transmission link is used as a measuring arm of an optical fiber interferometer to obtain the phase drift of the transmission link, and phase compensation is carried out on the change of optical fiber time delay according to the phase drift detection result; the service signal and the detection light signal of the optical fiber phase compensator are transmitted on the optical fiber transmission link after phase compensation through the wavelength division multiplexing technology, so that the stable phase transmission is realized.

The conventional optical fiber phase compensator, such as an optical fiber phase compensator and a use method thereof in chinese invention with application number CN201410173968, a cascaded optical fiber phase compensator and an optical fiber transmission system in chinese patent application number CN201710818733, an optical fiber phase compensator based on mach-zehnder optical fiber interferometer in chinese patent application number CN201810863552, and the like, realizes phase drift detection by arranging the optical fiber interferometer between an ROF signal transmitting end and an ROF signal receiving end. Although these fiber phase compensators can achieve phase compensation accuracy of ± λ/4 (λ is a wavelength of a detection light source of the fiber phase compensator) on a short fiber of the order of 100m, phase compensation accuracy of less than 0.1ps can be achieved on a long fiber of several tens of kilometers. However, when the existing optical fiber phase compensator performs phase drift detection, the problem that detection blind areas exist at positions of a signal transmitting end, a signal receiving end, a 1 × N distributor, a one-way relay optical path and the like is not considered, and the detection blind areas cause system errors of optical fiber phase-stable transmission due to the fact that corresponding phase compensation cannot be performed. Although these systematic errors are continuously acceptable phase noise for non-precision systems, they are not continuously acceptable phase noise for precision systems, especially over a wide temperature range and accumulation of multiple cascaded stages, which may cause phase noise outside the tolerance range of the system.

Disclosure of Invention

The invention aims to solve the problem that the phase compensation has errors due to the fact that the existing optical fiber phase compensator has a phase drift detection dead zone optical fiber section, and provides an optical fiber phase compensator of a high-precision optical fiber interferometer.

In order to solve the problems, the invention is realized by the following technical scheme:

an optical fiber phase compensator of a high-precision optical fiber interferometer is arranged on an optical fiber transmission link, wherein the optical fiber transmission link comprises 1 service signal transmitting end and 1 service signal receiving end; the optical fiber phase compensator comprises an input end optical fiber interferometer, an output end optical fiber interferometer, a control circuit and a phase compensation module; the input end optical fiber interferometer and the output end optical fiber interferometer have the same structure and are Michelson interferometers; each Michelson interferometer consists of a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler; the reflection end of the far-end wavelength division multiplexer of the input end optical fiber interferometer is connected with the service signal transmitting end; the reflection end of the far-end wavelength division multiplexer of the output end optical fiber interferometer is connected with the service signal receiving end; the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler; the reflection end of the local wavelength division multiplexer of the input end optical fiber interferometer is connected with the reflection end of the local wavelength division multiplexer of the output end optical fiber interferometer; 2 photoelectric detectors of the input end optical fiber interferometer and 2 photoelectric detectors of the output end optical fiber interferometer are connected with the input end of the control circuit; the output end of the control circuit is connected with the control end of the phase compensation module; the phase compensation module is arranged in a measuring arm between a common end of a far-end wavelength division multiplexer of the input end optical fiber interferometer and/or the output end optical fiber interferometer and a common end of a local wavelength division multiplexer.

In the scheme, the optical path from the far-end Faraday magnetic rotation reflector of the input-end optical fiber interferometer to the far-end wavelength division multiplexer of the input-end optical fiber interferometer is equal to the optical path from the service signal transmitting end to the far-end wavelength division multiplexer of the input-end optical fiber interferometer; the optical path from the far-end Faraday magnetic rotation reflector of the output-end optical fiber interferometer to the far-end wavelength division multiplexer of the output-end optical fiber interferometer is equal to the optical path from the service signal receiving end to the far-end wavelength division multiplexer of the output-end optical fiber interferometer; for an optical path L1 from the local wavelength division multiplexer of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer, an optical path L2 from the local Faraday magnetic rotation mirror of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer; an optical path L4 from the local wavelength division multiplexer of the output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer, and an optical path L5 from the local Faraday magnetic rotation reflector of the output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer; an optical path L3 from the local wavelength division multiplexer of the input end optical fiber interferometer to the local wavelength division multiplexer of the output end optical fiber interferometer; satisfies L3 ═ L1-L2+ L4-L5; or L3 ═ L1-L2 and L4 ═ L5; or L3-L4-L5 and L1-L2.

In the above scheme, the control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the output end optical fiber interferometer, and then controls the phase compensation module to perform phase compensation.

The optical fiber phase compensator of another high-precision optical fiber interferometer is arranged on an optical fiber transmission link, and the optical fiber transmission link comprises 1 service signal transmitting end, a 1 xN optical fiber branching unit and N service signal receiving ends; the optical fiber phase compensator comprises 1 input end optical fiber interferometer, N output end optical fiber interferometers, a control circuit and N phase compensation modules; the 1 input end optical fiber interferometer and the N output end optical fiber interferometers have the same structure and are Michelson interferometers; each Michelson interferometer consists of a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler; the reflection end of the far-end wavelength division multiplexer of the input end optical fiber interferometer is connected with the service signal transmitting end, and the reflection end of the far-end wavelength division multiplexer of each output end optical fiber interferometer is connected with the corresponding service signal receiving end; the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler; the reflecting end of a local wavelength division multiplexer of the input end optical fiber interferometer is connected with the input end of the 1 XN optical fiber branching unit; the reflection end of the local wavelength division multiplexer of the N output end optical fiber interferometers is connected with N output ends of the 1 XN optical fiber branching unit; the 2 photoelectric detectors of the input end optical fiber interferometer and the 2 photoelectric detectors of each output end optical fiber interferometer are respectively connected with the input end of the control circuit; the output end of the control circuit is connected with the control ends of the N phase compensation modules; the N phase compensation modules are arranged in a measurement arm between a common end of a far-end wavelength division multiplexer and a common end of a local wavelength division multiplexer of the N output-end optical fiber interferometers; n is a positive integer of 2 or more.

In the scheme, the optical path from the far-end Faraday magnetic rotation reflector of the input-end optical fiber interferometer to the far-end wavelength division multiplexer of the input-end optical fiber interferometer is equal to the optical path from the service signal transmitting end to the far-end wavelength division multiplexer of the input-end optical fiber interferometer; the optical path from the far-end Faraday magnetic rotation reflector of each output-end optical fiber interferometer to the far-end wavelength division multiplexer of the output-end optical fiber interferometer is equal to the optical path from the service signal receiving end to the far-end wavelength division multiplexer of the output-end optical fiber interferometer; for an optical path L1 from the local wavelength division multiplexer of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer, an optical path L2 from the local Faraday magnetic rotation mirror of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer; the optical path length from the local wavelength division multiplexer of each output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer is L41, L42, … … and L4N, and the optical path length from the local Faraday magnetic rotation mirror of each output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer is L51, L52, … … and L5N; optical paths L31, L32, … …, L3N from the local wavelength division multiplexer of the input end fiber optic interferometer to the local wavelength division multiplexer of each output end fiber optic interferometer; satisfies L3 i-L1-L2 + L4i-L5 i; or L3i ═ L1-L2 and L4i ═ L5 i; or L3i ═ L4i-L5i and L1 ═ L2; the above i ═ 1,2, … …, N; n is a positive integer greater than or equal to 2.

In the scheme, the control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the ith output end optical fiber interferometer to control the ith phase compensation module to perform phase compensation; the above i ═ 1,2, … …, N; n is a positive integer greater than or equal to 2.

The optical fiber phase compensator of the high-precision optical fiber interferometer is arranged on a relay optical fiber transmission link, the relay optical fiber transmission link comprises 1 relay service signal input end and 1 relay service signal output end, and a one-way relay amplifier is arranged between the relay service signal input end and the relay service signal output end; the optical fiber phase compensator comprises a relay end first optical fiber interferometer, a relay end second interferometer, a relay control circuit and a relay phase compensation module; the first optical fiber interferometer at the relay end is a Mach-Zehnder optical fiber interferometer; the Mach-Zehnder optical fiber interferometer consists of an input end optical fiber coupler, an input end wavelength division multiplexer, an output end demultiplexer, an output end optical fiber coupler, a reference arm depolarizer, a measurement arm depolarizer, 2 photoelectric detectors and a narrow line width laser; the input end optical fiber coupler at least comprises 3 ports, wherein 1 port is positioned at one side of the input end optical fiber coupler, and the other 2 ports are positioned at the other side of the input end optical fiber coupler; the outgoing end optical fiber coupler at least comprises 4 ports, wherein 2 ports are positioned on one side of the incoming end optical fiber coupler, and the other 2 ports are positioned on the other side of the incoming end optical fiber coupler; the second interferometer at the relay end is a Michelson interferometer; the Michelson interferometer comprises a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler; the reflection end of the incoming wavelength division multiplexer of the relay end first optical fiber interferometer is connected with the relay service signal input end, and the reflection end of the far-end wavelength division multiplexer of the relay end second optical fiber interferometer is connected with the service signal receiving end or the next-stage relay service signal input end; in the relay-end first optical fiber interferometer, the output end of the narrow-linewidth laser is connected with 1 port on one side of the input-end optical fiber coupler, and 2 ports on the other side of the input-end optical fiber coupler are respectively connected with the input end of the reference arm depolarizer and the transmission end of the input-end wavelength division multiplexer; the common end of the ingress wavelength division multiplexer is connected with the input end of a unidirectional relay amplifier of the relay optical fiber transmission link, and the output end of the unidirectional relay amplifier of the relay optical fiber transmission link is connected with the common end of the egress demultiplexer; the transmission end of the output end demultiplexer is connected with the input end of the measuring arm depolarizer; the output end of the reference arm depolarizer and the output end of the measurement arm depolarizer are respectively connected with 2 ports on one side of the output end optical fiber coupler; 2 ports on the other side of the output end optical fiber coupler are connected with 2 photoelectric detectors; the 2 photoelectric detectors are respectively connected with the input end of the relay control circuit; in the relay-end second interferometer, the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler; the reflection end of the outgoing end demultiplexer of the relay end first optical fiber interferometer is connected with the reflection end of the local wavelength division multiplexer of the relay end second interferometer; the 2 photoelectric detectors of the relay-end first optical fiber interferometer and the 2 photoelectric detectors of the relay-end second optical fiber interferometer are connected with the input end of a relay control circuit, the output end of the relay control circuit is connected with the control end of a relay phase compensation module, the relay phase compensation module is arranged in a measuring arm between the public end of a far-end wavelength division multiplexer of the relay-end second optical fiber interferometer and the public end of a local wavelength division multiplexer, or the relay phase compensation module is arranged in a measuring arm between an incoming-end wavelength division multiplexer and an outgoing-end demultiplexer of the relay-end first optical fiber interferometer.

In the scheme, the narrow linewidth laser of the relay-end first optical fiber interferometer can be replaced by a 1 × 2 optical fiber coupler and an erbium-doped optical fiber amplifier; wherein 1 input port of the 1 × 2 optical fiber coupler is connected with the transmission end of the far-end wavelength division multiplexer of the michelson interferometer of the first-stage optical fiber phase compensator, 2 output ports of the 1 × 2 optical fiber coupler are respectively connected with the erbium-doped optical fiber amplifier and the far-end faraday magnetic rotation reflector, and the output port of the erbium-doped optical fiber amplifier forms the output port of the narrow-linewidth laser light source.

In the above solution, the sum of the optical path length L3 from the output port 1 of the input optical fiber coupler of the first optical fiber interferometer at the relay end to the transmission end of the input wavelength division multiplexer of the first optical fiber interferometer at the relay end and the optical path length L5 from the transmission end of the output wavelength division multiplexer of the first optical fiber interferometer at the relay end to the input port 1 of the output optical fiber coupler of the first optical fiber interferometer at the relay end is equal to the optical path length L6 of the reference arm of the first optical fiber interferometer, that is, the optical path length L3+ L5 is L6; the optical path length L2 of the reflection end of the incoming wavelength division multiplexer of the relay-end first optical fiber interferometer at the reflection end of the michelson interferometer of the optical fiber phase compensator of the previous-stage relay is equal to the optical path length L1 of the transmission end of the remote wavelength division multiplexer of the michelson interferometer of the previous-stage optical fiber phase compensator at the far-end faraday magnetic rotating reflector of the michelson interferometer of the optical fiber phase compensator of the previous-stage relay, that is, L1 is L2; an optical path length L7 from the reflection end of the outgoing demultiplexer of the relay-end first optical fiber interferometer to the reflection end of the local wavelength division multiplexer of the relay-end second optical fiber interferometer is equal to an optical path length L8 from the transmission end of the local wavelength division multiplexer of the relay-end second optical fiber interferometer to the optical fiber coupler of the relay-end second optical fiber interferometer minus an optical path length L9 from the local faraday magnetic rotating mirror of the relay-end second optical fiber interferometer to the optical fiber coupler of the second optical fiber interferometer, namely, L7 is L8-L9; an optical path L10 from the transmission end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to the far-end faraday magnetic rotating reflector is equal to an optical path L11 from the reflection end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to a service signal receiving end detector or an optical fiber phase compensator of the next-stage relay to the input-end wavelength division multiplexer of the first optical fiber interferometer, namely L10 is equal to L11.

In the above scheme, when the relay phase compensation module is disposed in the measurement arm between the common end of the remote wavelength division multiplexer of the relay-end second interferometer and the common end of the local wavelength division multiplexer, the relay control circuit first multiplies a phase drift detection value detected by the relay-end first optical fiber interferometer by 2, and then sums the phase drift detection value with a phase drift detection value detected by the relay-end second interferometer to control the relay phase compensation module to perform phase compensation; when the relay phase compensation module is arranged in a measuring arm between the public end of the incoming-end wavelength division multiplexer and the public end of the outgoing-end demultiplexer of the relay-end first optical fiber interferometer, the relay control circuit divides a phase drift detection value detected by the relay-end second optical fiber interferometer by 2, sums the phase drift detection value detected by the relay-end first optical fiber interferometer and then controls the relay phase compensation module to perform phase compensation.

Compared with the prior art, the invention solves the problem that the phase compensation has errors due to the existence of the optical fiber sections of the optical fiber interferometer detection blind areas of the optical fiber phase compensator at the positions of a signal transmitting end, a signal receiving end, a 1 XN distributor, a one-way relay optical path and the like, and adopts an equal-length optical fiber substitution method, namely, the length of the non-public optical fiber section in the measuring arm of the optical fiber interferometer at the input end or the output end is consistent with the length of the blind area optical fiber, so that the phase drift of the blind area optical fiber is equivalently measured, the phase drift detection error minimization of the service optical signal transmitted in the optical fiber link is realized, and the higher phase compensation precision is obtained. Experiments show that when the length error of the equal-length substituted optical fiber is 1cm, the long-term (24h) system phase drift detection error caused by the equal-length substituted optical fiber is less than 10fs, and the short-term (1s) system phase drift detection error can be ignored.

Drawings

Fig. 1 is a schematic diagram of an optical structure of a fiber phase compensator (one-way output) of a first high-precision fiber interferometer.

Fig. 2 is a schematic diagram of ports and equal-length alternative optical fibers of an input remote wavelength division multiplexer and an output wavelength division multiplexer.

FIG. 3 is a schematic diagram of alternative optical fibers of equal length between the 2 fiber interferometers of FIG. 1.

Fig. 4 is an optical structure diagram of the fiber phase compensator (N-way output) of the second high-precision fiber interferometer.

FIG. 5 is a schematic diagram of equal length alternative optical fibers between the 2 fiber interferometers of FIG. 4.

Fig. 6 is a diagram illustrating an application of the present invention in long-distance transmission.

Fig. 7 is an optical structure diagram of a fiber phase compensator (with relay amplification and independent light source) of a third high-precision fiber interferometer.

Fig. 8 is a schematic diagram of the optical structure of the optical fiber phase compensator (with relay amplification and non-independent light source) of the fourth high-precision optical fiber interferometer.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to the accompanying drawings in conjunction with specific examples.

Example 1:

an optical fiber phase compensator of a high-precision optical fiber interferometer comprises 1 input end optical fiber interferometer, 1 output end optical fiber interferometer, 1 control circuit and 1 phase compensation module, as shown in figure 1. The optical fiber phase compensator is arranged on a 1 × 1 optical fiber transmission link, and the 1 × 1 optical fiber transmission link includes 1 service signal transmitting end and 1 service signal receiving end. The output end of the service signal transmitting end is connected with the input end of the service signal receiving end through an optical fiber cable.

The input end optical fiber interferometer is a Michelson optical fiber interferometer and comprises an input far-end wavelength division multiplexer, an input far-end Faraday magnetic rotation reflecting mirror, an input local wavelength division multiplexer, an input local Faraday magnetic rotation reflecting mirror, an input optical fiber coupler, 2 input photoelectric detectors (PD1 and PD2) and an input narrow linewidth laser. In the present invention, the input fiber coupler is a 3 × 3 fiber coupler, which includes 6 ports, wherein the first to third ports are located at one end of the fiber coupler; the third to sixth ports are located at the other end of the fiber coupler. The input remote wavelength division multiplexer includes three optical fiber ports, as shown in fig. 2, which are respectively a common port (port), a transmission port (port), and a reflection port (port), wherein the transmission port transmits phase drift detection laser, the reflection port transmits service signals, the common port transmits a combined wave signal of the two signals, and a starting point for calculating an optical path of the wavelength division multiplexer is a WDM wave plate.

And the reflection end of the input far-end wavelength division multiplexer is connected with the service signal transmitting end. And the transmission end of the input far-end wavelength division multiplexer is connected with the input far-end Faraday magnetic rotation reflector. And the common end of the input remote wavelength division multiplexer is connected with the common end of the input local wavelength division multiplexer through an optical fiber jumper or a transmission optical cable. The transmission end of the input local wavelength division multiplexer is connected with the fifth port of the input 3X 3 optical fiber coupler, the input local Faraday magnetic rotation reflector is connected with the sixth port of the input 3X 3 optical fiber coupler, and the input narrow linewidth laser is connected with the first port of the input 3X 3 optical fiber coupler. The second port and the third port of the input 3 × 3 fiber coupler are respectively connected to corresponding 2 input photodetectors (PD1 and PD2), and are connected to the input end of the control circuit.

The first port to the third port of the input 3 x 3 optical fiber coupler are input ports which are respectively connected with the input narrow linewidth laser and the two photoelectric detectors, and the connection sequence has no requirement; the fourth port to the sixth port of the input 3 x 3 optical fiber coupler are output ports which are respectively connected with the transmission end of the input local wavelength division multiplexer and the Faraday magnetic rotating reflector, and one port is vacant, and the connection sequence has no requirement; but the input port and the output port of the input 3 x 3 optical fiber coupler cannot be connected in a wrong way.

The output end optical fiber interferometer is a Michelson optical fiber interferometer and comprises an output far-end wavelength division multiplexer, an output far-end Faraday magnetic rotation reflecting mirror, an output local wavelength division multiplexer, an output local Faraday magnetic rotation reflecting mirror, an output optical fiber coupler, 2 output photoelectric detectors (PD3 and PD4) and an output narrow linewidth laser. In the present invention, the output fiber coupler is a 3 × 3 fiber coupler, which includes 6 ports, wherein the first to third ports are located at one end of the fiber coupler; the third to sixth ports are located at the other end of the fiber coupler. The output remote wavelength division multiplexer includes three optical fiber ports, as shown in fig. 2, which are respectively a common port (port), a transmission port (port), and a reflection port (port), wherein the transmission port transmits phase drift detection laser, the reflection port transmits service signals, the common port transmits a combined wave signal of the two signals, and a starting point for calculating an optical path of the wavelength division multiplexer is a WDM wave plate.

And the reflection end of the output remote wavelength division multiplexer is connected with a service signal receiving end. And the transmission end of the output far-end wavelength division multiplexer is connected with the output far-end Faraday magnetic rotation reflector. And the common end of the output remote wavelength division multiplexer is connected with the common end of the output local wavelength division multiplexer through an optical fiber jumper or a transmission optical cable. The transmission end of the output local wavelength division multiplexer is connected with the fifth port of the output 3 x 3 optical fiber coupler, the output local Faraday magnetic rotation reflector is connected with the sixth port of the output 3 x 3 optical fiber coupler, and the output narrow linewidth laser is connected with the first port of the output 3 x 3 optical fiber coupler. The second port and the third port of the output 3 × 3 fiber coupler are respectively connected to the corresponding 2 photodetectors (PD3 and PD4), and are connected to the input end of the control circuit.

Outputting a first port to a third port of the 3 x 3 optical fiber coupler, and respectively connecting an input narrow linewidth laser and two photoelectric detectors, wherein the connection sequence has no requirement; a fourth port of the output 3 multiplied by 3 optical fiber coupler is connected to a sixth connecting port, the fourth port is connected to the transmission end of the input local wavelength division multiplexer and the Faraday magnetic rotation reflector respectively, and a port is vacant, so that the connection sequence has no requirement; but the input port and the output port of the output 3 x 3 optical fiber coupler cannot be connected in a wrong way.

And the reflection end of the input local wavelength division multiplexer of the input end optical fiber interferometer is connected with the reflection end of the output local wavelength division multiplexer of the output end optical fiber interferometer. The output end of the control circuit is connected with the control end of the phase compensation module. And the control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the output end optical fiber interferometer and controls the phase compensation module to perform phase compensation.

In a preferred embodiment of the present invention, the input remote wavelength division multiplexer and the input remote faraday magnetic rotation mirror are disposed within a housing of the service signal transmitting apparatus. The output far-end wavelength division multiplexer and the output far-end Faraday magnetic rotation reflector are arranged in a shell of the service signal receiving device. The input local wavelength division multiplexer, the input local Faraday magnetic rotation reflector, the input optical fiber coupler, 2 input photoelectric detectors, the input narrow line width laser, the output local wavelength division multiplexer, the output local Faraday magnetic rotation reflector, the output optical fiber coupler, 2 output photoelectric detectors, the output narrow line width laser, the phase compensation module and the control circuit are arranged in a shell of an independent optical fiber phase compensation device. The input narrow linewidth laser of the input end optical fiber interferometer and the output narrow linewidth laser of the output end optical fiber interferometer can respectively adopt independent lasers or share the same laser. In a preferred embodiment of the invention, the input narrow linewidth laser and the output narrow linewidth laser are both narrow linewidth lasers.

The phase compensation module is arranged in a measuring arm of the input end fiber optic interferometer and/or the output end fiber optic interferometer. In the invention, the setting modes of the phase compensation module comprise three modes, and any one of the three modes can be selected to realize the phase compensation function:

when the phase compensation module is arranged in the measuring arm of the input end fiber interferometer: the phase compensation module is arranged between the common end of the local wavelength division multiplexer of the input end optical fiber interferometer and the common end of the far end wavelength division multiplexer of the input end optical fiber interferometer;

when the phase compensation module is arranged in the measuring arm of the output end fiber interferometer: the phase compensation module is arranged between the common end of the local wavelength division multiplexer of the output end optical fiber interferometer and the common end of the far end wavelength division multiplexer of the output end optical fiber interferometer;

when the phase compensation module is arranged in the measuring arms of the input end fiber interferometer and the output end fiber interferometer: the phase compensation module comprises 2 parts, one part of the phase compensation module is arranged between the common end of the local wavelength division multiplexer of the input end optical fiber interferometer and the common end of the remote wavelength division multiplexer of the input end optical fiber interferometer, and the other part of the phase compensation module is arranged between the common end of the local wavelength division multiplexer of the output end optical fiber interferometer and the common end of the remote wavelength division multiplexer of the output end optical fiber interferometer.

The invention adopts an equal-length optical fiber substitution method for the phase measurement blind area optical fibers of the ROF signal transmitting end and the ROF signal receiving end in the service signal optical fiber transmission link, namely, the length of the non-common optical fiber section in the measuring arms of the input end optical fiber interferometer and the output end optical fiber interferometer is consistent with the length of the blind area optical fiber, thereby equivalently measuring the phase drift of the blind area optical fiber. And then, the control circuit detects the sum of the phase drifts of the input end optical fiber interferometer and the output end optical fiber interferometer and controls the phase compensation module to perform phase compensation, so that the phase drift detection error minimization of service optical signals transmitted in an optical fiber link can be realized, and the phase compensation precision is improved. The equal-length optical fiber replacement method adopted by the invention, as shown in fig. 2 and 3, comprises three parts:

one is far end of input end fiber optic interferometer: the optical path from an input far-end Faraday magnetic rotation reflector of the input end optical fiber interferometer to the input far-end wavelength division multiplexer is equal to the optical path from a service signal transmitting end to the input far-end wavelength division multiplexer;

the second means the far end of the output end optical fiber interferometer: the optical path from the output far-end Faraday magnetic rotation reflector of the output end optical fiber interferometer to the output far-end wavelength division multiplexer is equal to the optical path from the service signal receiving end to the output far-end wavelength division multiplexer;

the third is between the input end fiber interferometer and the output end fiber interferometer: in the input end fiber interferometer, the optical path L1 between the local wavelength division multiplexer and the input fiber coupler is input, and the optical path L2 between the local Faraday magnetic rotation mirror and the input fiber coupler is input. In the output end fiber interferometer, an optical path L4 between the local wavelength division multiplexer and the output fiber coupler is output, and an optical path L5 between the local Faraday magnetic rotation mirror and the output fiber coupler is output. An optical path L3 between the input and output local wavelength division multiplexers between the input and output optical fibre interferometers. Satisfies L3 ═ L1-L2+ L4-L5; or L3 ═ L1-L2, and L4 ═ L5; or L3-L4-L5 and L1-L2.

Example 2:

an optical fiber phase compensator of a high-precision optical fiber interferometer comprises 1 input end optical fiber interferometer, N output end optical fiber interferometers, 1 control circuit and N phase compensation modules, as shown in figure 4. The optical fiber phase compensator is arranged on a 1 × N optical fiber transmission link, and the 1 × N optical fiber transmission link includes 1 service signal (ROF) transmitting end, 1 × N optical fiber splitter, and N service signal (ROF) receiving ends. The output end of the service signal transmitting end is connected with the input end of the 1 XN optical fiber branching unit through an optical fiber cable, and the N output ends of the 1 XN optical fiber branching unit are respectively connected with the N service signal receiving ends through optical fiber cables. N is a positive integer of 2 or more.

And the reflection end of the input far-end wavelength division multiplexer is connected with the service signal transmitting end. And the transmission end of the input far-end wavelength division multiplexer is connected with the input far-end Faraday magnetic rotation reflector. And the common end of the input far-end wavelength division multiplexer is connected with the common end of the local wavelength division multiplexer through an optical fiber jumper or a transmission optical cable. The transmission end of the input local wavelength division multiplexer is connected with the fifth port of the input 3X 3 optical fiber coupler, the input local Faraday magnetic rotation reflector is connected with the sixth port of the input 3X 3 optical fiber coupler, and the input narrow linewidth laser is connected with the first port of the input 3X 3 optical fiber coupler. The second port and the third port of the input 3 × 3 fiber coupler are respectively connected to corresponding 2 input photodetectors (PD1 and PD2), and are connected to the input end of the control circuit.

Inputting a first port to a third port of a 3 x 3 optical fiber coupler, and respectively connecting an input narrow linewidth laser and two photoelectric detectors, wherein the connection sequence has no requirement; the fourth port of the input 3X 3 optical fiber coupler is connected to the sixth connector, and the fourth port is connected to the transmission end of the input local wavelength division multiplexer and the Faraday magnetic rotating reflector respectively, and the fourth port is vacant, and the connection sequence has no requirement; but the ports on the two sides of the input 3X 3 fiber coupler can not be connected in a wrong way.

N output fiber optic interferometers's structure is the same, and every output fiber optic interferometer is Michelson fiber optic interferometer, including output distal end wavelength division multiplexer, output distal end Faraday magnetic rotation speculum, output local wavelength division multiplexer, output local Faraday magnetic rotation speculum, output fiber coupler, 2 output photoelectric detector (PD3i and PD4i, i 1,2 … N) and output narrow linewidth laser. In the present invention, the output fiber coupler is a 3 × 3 fiber coupler, which includes 6 ports, wherein the first to third ports are located at one end of the fiber coupler; the third to sixth ports are located at the other end of the fiber coupler. The output remote wavelength division multiplexer includes three optical fiber ports, as shown in fig. 2, which are respectively a common port (port), a transmission port (port), and a reflection port (port), wherein the transmission port transmits phase drift detection laser, the reflection port transmits service signals, the common port transmits a combined wave signal of the two signals, and a starting point for calculating an optical path of the wavelength division multiplexer is a WDM wave plate.

And the reflection end of the output remote wavelength division multiplexer is connected with a service signal receiving end. And the transmission end of the output far-end wavelength division multiplexer is connected with the output far-end Faraday magnetic rotation reflector. The public end of the output remote wavelength division multiplexer is directly connected with the public end of the output local wavelength division multiplexer; or the public end of the output far-end wavelength division multiplexer is connected with the output optical fiber cable of the optical fiber phase compensator and then connected with the public end of the output local wavelength division multiplexer through the output optical fiber cable. The transmission end of the output local wavelength division multiplexer is connected with the fifth port of the output 3 x 3 optical fiber coupler, the output local Faraday magnetic rotation reflector is connected with the sixth port of the output 3 x 3 optical fiber coupler, and the output narrow linewidth laser is connected with the first port of the output 3 x 3 optical fiber coupler. The second port and the third port of the output 3 × 3 fiber coupler are respectively connected to corresponding 2 output photodetectors (PD3i and PD4i, i is 1,2 … N), and are connected to the input end of the control circuit.

Outputting a first port to a third port of the 3 x 3 optical fiber coupler, and respectively connecting an input narrow linewidth laser and two photoelectric detectors, wherein the connection sequence has no requirement; a fourth port of the output 3 multiplied by 3 optical fiber coupler is connected to a sixth connecting port, the fourth port is connected to the transmission end of the input local wavelength division multiplexer and the Faraday magnetic rotation reflector respectively, and a port is vacant, so that the connection sequence has no requirement; but the ports on the two sides of the output 3X 3 fiber coupler can not be connected in a wrong way.

The reflection end of the input local wavelength division multiplexer is connected with the input end of the 1 XN optical fiber branching device, and each output end of the 1 XN optical fiber branching device is respectively connected with the reflection end of the output local wavelength division multiplexer of each output end optical fiber interferometer. The output end of the control circuit is connected with the control end of the phase compensation module. The control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the ith output end optical fiber interferometer to control the ith phase compensation module to perform phase compensation; the above i is 1,2, … …, N.

In a preferred embodiment of the present invention, the input remote wavelength division multiplexer and the input remote faraday magnetic rotation mirror are disposed within a housing of the service signal transmitting apparatus. The output far-end wavelength division multiplexer and the output far-end Faraday magnetic rotation reflector are arranged in a shell of the service signal connection receiving device. The input local wavelength division multiplexer, the input local Faraday magnetic rotation reflector, the input optical fiber coupler, 2 input optical detectors, the input narrow line width laser, the 1 XN optical fiber splitter, N output local wavelength division multiplexers, N output local Faraday magnetic rotation reflectors, N output optical fiber couplers, 2N output optical detectors, N output narrow line width lasers, N phase compensation modules and the control circuit are arranged in a shell of an independent optical fiber phase compensation device. The input narrow linewidth laser of the input end optical fiber interferometer and the output narrow linewidth lasers of the N output end optical fiber interferometers can respectively adopt independent lasers or share the same laser. In a preferred embodiment of the invention, the input narrow linewidth laser and the output narrow linewidth laser are both narrow linewidth lasers.

The N phase compensation modules are arranged in the measuring arms of the N output end optical fiber interferometers. In the invention, the setting mode of the phase compensation module comprises two modes, and any one of the two modes can be selected to realize the phase compensation function:

firstly, set up in every output fiber optic interferometer's measuring arm: the phase compensation module comprises N branch phase compensation modules, and each branch phase compensation module is arranged between the common end of the output local wavelength division multiplexer and the output optical fiber connector. At the moment, the phase compensation module compensates the sum of phase drifts detected by the input end interferometer and the output end interferometer of the branch, and the setting mode can carry out independent phase compensation on each output branch.

Secondly, the device is arranged in the input end fiber interferometer measuring arm and each output end interferometer measuring arm: the phase compensation module comprises two parts, namely a 1 main path phase compensation module and an N branch path phase compensation module; the main path phase compensation module is arranged between the optical fiber connector of the optical fiber phase compensator and the common end of the input local wavelength division multiplexer, and is generally provided with a wide-range phase compensation module which is used for compensating a wide-range part of phase drift detected by the input interferometer and each output interferometer; each branch phase compensation module is arranged between the common end of the output local wavelength division multiplexer and the output optical fiber connector of the optical fiber phase compensator, a high-precision phase compensation module is generally arranged in each branch phase compensation module, and the high-precision phase compensation module is used for compensating the residual phase drift part of the wide-range phase compensation module of the sum of the phase drifts detected by the input interferometer and the corresponding output interferometer.

The invention adopts an equal-length optical fiber substitution method for the phase measurement blind area optical fibers of the ROF signal transmitting end and the ROF signal receiving end in the service signal optical fiber transmission link, namely, the length of the non-common optical fiber section in the measuring arms of the input end optical fiber interferometer and the output end optical fiber interferometer is consistent with the length of the blind area optical fiber, thereby equivalently measuring the phase drift of the blind area optical fiber. And then, the control circuit detects the sum of the phase drifts of the input end optical fiber interferometer and all the output end optical fiber interferometers and controls the phase compensation module to perform phase compensation, so that the phase drift detection error minimization of service optical signals transmitted in an optical fiber link can be realized, and the phase compensation precision is improved. The equal-length optical fiber replacement method adopted by the invention is shown in fig. 2 and 5, and one of the equal-length optical fiber replacement methods comprises three parts:

one refers to the far end of the input end fiber optic interferometer: the optical path from an input far-end Faraday magnetic rotation reflector of the input end optical fiber interferometer to the input far-end wavelength division multiplexer is equal to the optical path from a service signal transmitting end to the input far-end wavelength division multiplexer;

second, refer to the distal end of each output end fiber optic interferometer: the optical path from the output far-end Faraday magnetic rotation reflector of the output end optical fiber interferometer to the corresponding output far-end wavelength division multiplexer is equal to the optical path from the service signal receiving end to the corresponding output far-end wavelength division multiplexer;

the third is between the input end fiber interferometer and the output end fiber interferometer: in the input end fiber interferometer, the optical path L1 between the local wavelength division multiplexer and the input fiber coupler is input, and the optical path L2 between the local Faraday magnetic rotation mirror and the input fiber coupler is input. In each output end fiber optic interferometer, optical paths L41, L42, … … and L4N between the local wavelength division multiplexer and the corresponding output fiber optic coupler are output, and optical paths L51, L52, L … … and L5N between the local Faraday magnetic rotation mirror and the corresponding output fiber optic coupler are output. Between the input end fiber interferometer and the output end fiber interferometer, the input local wavelength division multiplexer passes through the input end of the 1 XN fiber splitter, the N input ends of the 1 XN fiber splitter and the optical paths L31, L32, … … and L3N to the N output local wavelength division multiplexers. Satisfies L3 i-L1-L2 + L4i-L5 i; or L3i ═ L1-L2, and L4i ═ L5 i; or L3i ═ L4i-L5i and L1 ═ L2; where i is 1,2, … …, N.

Example 3

Considering that in practical applications, when the length of the optical fiber transmission link between the service signal transmitting end and the service signal receiving end is longer, for example, exceeds 50km, if the optical fiber phase compensator is only arranged at the service signal transmitting end (as in embodiments 1 and 2), the compensation effect on the whole optical fiber transmission link is still not good, and therefore, an optical fiber phase compensator of a trunk section needs to be additionally arranged in the trunk section (i.e., the trunk optical fiber transmission link) of the optical fiber transmission link. As shown in fig. 6, when the relay optical fiber transmission link is a normal non-unidirectional link, the optical fiber phase compensator of the relay segment may be formed by 2 relay michelson interferometers, a relay control circuit and a relay phase compensation module, which is similar to embodiment 1 and will not be described herein again. When the relay optical fiber transmission link is a unidirectional link provided with a unidirectional relay amplifier, the optical fiber phase compensator of the relay segment may be formed by 1 relay mach-zehnder optical fiber interferometer, 1 relay michelson interferometer, a relay control circuit, and a relay phase compensation module, and this manner is the key point described in this embodiment 3. By adopting the mode of mutually cascading the plurality of optical fiber phase compensators, the 1000km optical fiber phase-stabilized transmission system can realize the compensation precision of which the instantaneous and long-term phase drift compensation errors are less than 1 ps.

The optical fiber phase compensator of the high-precision optical fiber interferometer is arranged on a relay optical fiber transmission link, the relay optical fiber transmission link comprises 1 relay service signal input end and 1 relay service signal output end, and a one-way relay amplifier is arranged between the relay service signal input end and the relay service signal output end.

The optical fiber phase compensator comprises a relay end first optical fiber interferometer, a relay end second interferometer, a relay control circuit and a relay phase compensation module;

the relay-end first optical fiber interferometer is a Mach-Zehnder optical fiber interferometer. The Mach-Zehnder optical fiber interferometer comprises an input end optical fiber coupler, an input end wavelength division multiplexer, an output end demultiplexer, an output end optical fiber coupler, a reference arm depolarizer, a measurement arm depolarizer, 2 photoelectric detectors and a narrow linewidth laser. The input end optical fiber coupler at least comprises 3 ports, wherein 1 port is positioned on one side of the input end optical fiber coupler, and the other 2 ports are positioned on the other side of the input end optical fiber coupler. In this embodiment, the input optical fiber coupler is a 1 × 2 optical fiber coupler. The outgoing optical fiber coupler at least comprises 4 ports, wherein 2 ports are positioned on one side of the incoming optical fiber coupler, and the other 2 ports are positioned on the other side of the incoming optical fiber coupler. In this embodiment, the outgoing fiber coupler is a 3 × 3 fiber coupler.

The second interferometer at the relay end is a Michelson interferometer. The Michelson interferometer comprises a far-end wavelength division multiplexer, a far-end Faraday magnetic rotation reflector, a local wavelength division multiplexer, a local Faraday magnetic rotation reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser. The optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler. In this embodiment, the fiber coupler is a 3 × 3 fiber coupler.

In the relay-end first optical fiber interferometer, the output end of the narrow-linewidth laser is connected with 1 port on one side of the input-end optical fiber coupler, and 2 ports on the other side of the input-end optical fiber coupler are respectively connected with the input end of the reference arm depolarizer and the transmission end of the input-end wavelength division multiplexer; the common end of the ingress wavelength division multiplexer is connected with the input end of a unidirectional relay amplifier of the relay optical fiber transmission link, and the output end of the unidirectional relay amplifier of the relay optical fiber transmission link is connected with the common end of the egress demultiplexer; the transmission end of the output end demultiplexer is connected with the input end of the measuring arm depolarizer; the output end of the reference arm depolarizer and the output end of the measurement arm depolarizer are respectively connected with 2 ports on one side of the output end optical fiber coupler; 2 ports on the other side of the output end optical fiber coupler are connected with 2 photoelectric detectors; the 2 photoelectric detectors are respectively connected with the input end of the relay control circuit.

In the relay-end second interferometer, the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler.

The reflection end of the incoming wavelength division multiplexer of the first relay-end optical fiber interferometer is connected with the input end of the relay service signal, and the reflection end of the far-end wavelength division multiplexer of the second relay-end optical fiber interferometer is connected with the input end of the relay service signal. And the reflection end of the outgoing demultiplexer of the relay-end first optical fiber interferometer is connected with the reflection end of the local wavelength division multiplexer of the relay-end second interferometer.

The input end optical fiber coupler and the output end optical fiber coupler of the relay end first optical fiber interferometer and 2 photoelectric detectors of the relay end second interferometer are connected with the input end of a relay control circuit, the output end of the relay control circuit is connected with the control end of a relay phase compensation module, the relay phase compensation module is arranged in a measuring arm between the public end of a far-end wavelength division multiplexer of the relay end second interferometer and the public end of a local wavelength division multiplexer, or the relay phase compensation module is arranged in a measuring arm between the input end wavelength division multiplexer and the output end demultiplexer of the relay end first optical fiber interferometer.

When the relay phase compensation module is arranged in a measuring arm between the public end of the far-end wavelength division multiplexer of the relay-end second interferometer and the public end of the local wavelength division multiplexer, the relay control circuit multiplies a phase drift detection value detected by the relay-end first optical fiber interferometer by 2, sums the phase drift detection value detected by the relay-end second interferometer and controls the relay phase compensation module to perform phase compensation. When the relay phase compensation module is arranged in a measuring arm between the public end of the incoming-end wavelength division multiplexer and the public end of the outgoing-end demultiplexer of the relay-end first optical fiber interferometer, the relay control circuit divides a phase drift detection value detected by the relay-end second optical fiber interferometer by 2, sums the phase drift detection value detected by the relay-end first optical fiber interferometer and then controls the relay phase compensation module to perform phase compensation.

In the above scheme, the narrow linewidth laser of the relay-side first optical fiber interferometer and the narrow linewidth laser of the relay-side second optical fiber interferometer may share the same laser, or may use separate lasers, as shown in fig. 7. The narrow linewidth laser of the relay-end first optical fiber interferometer and the narrow linewidth laser of the relay-end second optical fiber interferometer can also be used for leading out detection laser from the output-end optical fiber interferometer of the previous-stage optical fiber phase compensator and splitting the detection laser into two interferometers to provide coherent light sources to replace the narrow linewidth laser, as shown in fig. 8, the narrow linewidth laser of the relay-end first optical fiber interferometer is led out from the previous-stage relay optical fiber transmission link, and at the moment, the narrow linewidth laser source of the relay-end first optical fiber interferometer is composed of a 1 x 2 optical fiber coupler and an erbium-doped optical fiber amplifier; wherein 1 input port of the 1 × 2 optical fiber coupler is connected with the transmission end of the far-end wavelength division multiplexer of the michelson interferometer of the first-stage optical fiber phase compensator, 2 output ports of the 1 × 2 optical fiber coupler are respectively connected with the input end of the erbium-doped optical fiber amplifier and the far-end faraday magnetic rotation reflector of the previous-stage optical fiber phase compensator, the output end of the erbium-doped optical fiber amplifier forms the output end of the narrow-linewidth laser, and the beam splitting provides a coherent light source for the two local optical fiber interferometers.

On the basis of the equal-length optical fiber replacement of the embodiments 1 and 2, the embodiment 3 further includes the following equal-length optical fiber replacement schemes:

the sum of an optical path L3 from the input optical fiber coupler of the first optical fiber interferometer at the relay end to the transmission end of the input optical fiber multiplexer of the first optical fiber interferometer at the relay end and an optical path L5 from the transmission end of the wavelength division multiplexer at the output end of the first optical fiber interferometer at the relay end to the output optical fiber coupler of the first optical fiber interferometer at the relay end is equal to the optical path of the reference arm of the first optical fiber interferometer at the relay end, namely, an optical path L6 from the other output port of the input optical fiber coupler to the other input port of the output optical fiber coupler, namely, L3+ L5 is equal to L6;

the optical path length L2 of the reflection end of the incoming wavelength division multiplexer of the relay-end first optical fiber interferometer is equal to the optical path length L1 of the reflection end of the remote wavelength division multiplexer of the michelson interferometer of the optical fiber phase compensator of the previous relay, namely L1 is equal to L2;

an optical path L7 from the reflection end of the outgoing demultiplexer of the first optical fiber interferometer at the relay end to the reflection end of the local wavelength division multiplexer of the second optical fiber interferometer at the relay end is equal to an optical path L8 from the transmission end of the local wavelength division multiplexer of the second optical fiber interferometer at the relay end to the optical fiber coupler of the second optical fiber interferometer at the relay end minus an optical path L9 from the local faraday magnetic rotating mirror of the second optical fiber interferometer at the relay end to the optical fiber coupler, namely, L7 is L8-L9;

an optical path L10 from the transmission end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to the far-end faraday magnetic rotating reflector is equal to an optical path L11 from the reflection end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to a service signal receiving end detector or an incoming-end wavelength division multiplexer of the first optical fiber phase compensator of the next-stage relay, that is, L10 is equal to L11.

It should be noted that, although the above-mentioned embodiments of the present invention are illustrative, the present invention is not limited thereto, and thus the present invention is not limited to the above-mentioned embodiments. Other embodiments, which can be made by those skilled in the art in light of the teachings of the present invention, are considered to be within the scope of the present invention without departing from its principles.

Claims

1. An optical fiber phase compensator of a high-precision optical fiber interferometer is arranged on an optical fiber transmission link, wherein the optical fiber transmission link comprises 1 service signal transmitting end and 1 service signal receiving end; the method is characterized in that:

the optical fiber phase compensator comprises an input end optical fiber interferometer, an output end optical fiber interferometer, a control circuit and a phase compensation module;

the input end optical fiber interferometer and the output end optical fiber interferometer have the same structure and are Michelson interferometers; each Michelson interferometer consists of a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler;

the reflection end of the far-end wavelength division multiplexer of the input end optical fiber interferometer is connected with the service signal transmitting end; the reflection end of the far-end wavelength division multiplexer of the output end optical fiber interferometer is connected with the service signal receiving end;

the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler;

the reflection end of the local wavelength division multiplexer of the input end optical fiber interferometer is connected with the reflection end of the local wavelength division multiplexer of the output end optical fiber interferometer;

2 photoelectric detectors of the input end optical fiber interferometer and 2 photoelectric detectors of the output end optical fiber interferometer are connected with the input end of the control circuit; the output end of the control circuit is connected with the control end of the phase compensation module; the phase compensation module is arranged in a measuring arm between a common end of a far-end wavelength division multiplexer of the input end optical fiber interferometer and/or the output end optical fiber interferometer and a common end of the local wavelength division multiplexer;

the optical path from the far-end Faraday magnetic rotation reflector of the input end optical fiber interferometer to the far-end wavelength division multiplexer of the input end optical fiber interferometer is equal to the optical path from the service signal transmitting end to the far-end wavelength division multiplexer of the input end optical fiber interferometer;

the optical path from the far-end Faraday magnetic rotation reflector of the output-end optical fiber interferometer to the far-end wavelength division multiplexer of the output-end optical fiber interferometer is equal to the optical path from the service signal receiving end to the far-end wavelength division multiplexer of the output-end optical fiber interferometer;

for an optical path L1 from the local wavelength division multiplexer of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer, an optical path L2 from the local Faraday magnetic rotation mirror of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer; an optical path L4 from the local wavelength division multiplexer of the output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer, and an optical path L5 from the local Faraday magnetic rotation reflector of the output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer; an optical path L3 from the local wavelength division multiplexer of the input end optical fiber interferometer to the local wavelength division multiplexer of the output end optical fiber interferometer; satisfies L3 ═ L1-L2+ L4-L5; or L3 ═ L1-L2 and L4 ═ L5; or L3-L4-L5 and L1-L2.

2. The fiber phase compensator of a high precision fiber optic interferometer according to claim 1, wherein: and the control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the output end optical fiber interferometer and controls the phase compensation module to perform phase compensation.

3. An optical fiber phase compensator of a high-precision optical fiber interferometer is arranged on an optical fiber transmission link, wherein the optical fiber transmission link comprises 1 service signal transmitting end, a 1 xN optical fiber branching unit and N service signal receiving ends; the method is characterized in that:

the optical fiber phase compensator comprises 1 input end optical fiber interferometer, N output end optical fiber interferometers, a control circuit and N phase compensation modules;

the 1 input end optical fiber interferometer and the N output end optical fiber interferometers have the same structure and are Michelson interferometers; each Michelson interferometer consists of a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler;

the reflection end of the far-end wavelength division multiplexer of the input end optical fiber interferometer is connected with the service signal transmitting end, and the reflection end of the far-end wavelength division multiplexer of each output end optical fiber interferometer is connected with the corresponding service signal receiving end;

the reflecting end of a local wavelength division multiplexer of the input end optical fiber interferometer is connected with the input end of the 1 XN optical fiber branching unit; the reflection end of the local wavelength division multiplexer of the N output end optical fiber interferometers is connected with N output ends of the 1 XN optical fiber branching unit;

the 2 photoelectric detectors of the input end optical fiber interferometer and the 2 photoelectric detectors of each output end optical fiber interferometer are respectively connected with the input end of the control circuit; the output end of the control circuit is connected with the control ends of the N phase compensation modules; the N phase compensation modules are arranged in a measurement arm between a common end of a far-end wavelength division multiplexer and a common end of a local wavelength division multiplexer of the N output-end optical fiber interferometers;

the optical path from the far-end Faraday magnetic rotation reflector of each output-end optical fiber interferometer to the far-end wavelength division multiplexer of the output-end optical fiber interferometer is equal to the optical path from the service signal receiving end to the far-end wavelength division multiplexer of the output-end optical fiber interferometer;

for an optical path L1 from the local wavelength division multiplexer of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer, an optical path L2 from the local Faraday magnetic rotation mirror of the input end fiber optic interferometer to the fiber coupler of the input end fiber optic interferometer; the optical path length from the local wavelength division multiplexer of each output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer is L41, L42, … … and L4N, and the optical path length from the local Faraday magnetic rotation mirror of each output end optical fiber interferometer to the optical fiber coupler of the output end optical fiber interferometer is L51, L52, … … and L5N; optical paths L31, L32, … …, L3N from the local wavelength division multiplexer of the input end fiber optic interferometer to the local wavelength division multiplexer of each output end fiber optic interferometer; satisfies L3 i-L1-L2 + L4i-L5 i; or L3i ═ L1-L2 and L4i ═ L5 i; or L3i ═ L4i-L5i and L1 ═ L2; the above i ═ 1,2, … …, N;

n is a positive integer of 2 or more.

4. The optical fiber phase compensator of a high precision optical fiber interferometer according to claim 3, wherein: the control circuit sums the phase drift detection value detected by the input end optical fiber interferometer and the phase drift detection value detected by the ith output end optical fiber interferometer to control the ith phase compensation module to perform phase compensation; the above i ═ 1,2, … …, N; n is a positive integer greater than or equal to 2.

5. An optical fiber phase compensator of a high-precision optical fiber interferometer is arranged on a relay optical fiber transmission link, the relay optical fiber transmission link comprises 1 relay service signal input end and 1 relay service signal output end, and a one-way relay amplifier is arranged between the relay service signal input end and the relay service signal output end; the method is characterized in that:

the first optical fiber interferometer at the relay end is a Mach-Zehnder optical fiber interferometer; the Mach-Zehnder optical fiber interferometer consists of an input end optical fiber coupler, an input end wavelength division multiplexer, an output end demultiplexer, an output end optical fiber coupler, a reference arm depolarizer, a measurement arm depolarizer, 2 photoelectric detectors and a narrow line width laser; the input end optical fiber coupler at least comprises 3 ports, wherein 1 port is positioned at one side of the input end optical fiber coupler, and the other 2 ports are positioned at the other side of the input end optical fiber coupler; the outgoing end optical fiber coupler at least comprises 4 ports, wherein 2 ports are positioned on one side of the incoming end optical fiber coupler, and the other 2 ports are positioned on the other side of the incoming end optical fiber coupler;

the second interferometer at the relay end is a Michelson interferometer; the Michelson interferometer comprises a far-end wavelength division multiplexer, a far-end Faraday magnetic rotating reflector, a local wavelength division multiplexer, a local Faraday magnetic rotating reflector, an optical fiber coupler, 2 photoelectric detectors and a narrow linewidth laser; the optical fiber coupler at least comprises 5 ports, wherein 2 ports are positioned on one side of the optical fiber coupler, and the other 3 ports are positioned on the other side of the optical fiber coupler;

the reflection end of the incoming wavelength division multiplexer of the relay end first optical fiber interferometer is connected with the relay service signal input end, and the reflection end of the far-end wavelength division multiplexer of the relay end second optical fiber interferometer is connected with the relay service signal input end;

in the relay-end first optical fiber interferometer, the output end of the narrow-linewidth laser is connected with 1 port on one side of the input-end optical fiber coupler, and 2 ports on the other side of the input-end optical fiber coupler are respectively connected with the input end of the reference arm depolarizer and the transmission end of the input-end wavelength division multiplexer; the common end of the ingress wavelength division multiplexer is connected with the input end of a unidirectional relay amplifier of the relay optical fiber transmission link, and the output end of the unidirectional relay amplifier of the relay optical fiber transmission link is connected with the common end of the egress demultiplexer; the transmission end of the output end demultiplexer is connected with the input end of the measuring arm depolarizer; the output end of the reference arm depolarizer and the output end of the measurement arm depolarizer are respectively connected with 2 ports on one side of the output end optical fiber coupler; 2 ports on the other side of the output end optical fiber coupler are connected with 2 photoelectric detectors; the 2 photoelectric detectors are respectively connected with the input end of the relay control circuit;

in the relay-end second interferometer, the transmission end of the far-end wavelength division multiplexer is connected with a far-end Faraday magnetic rotation reflector; the public end of the far-end wavelength division multiplexer is connected with the public end of the local wavelength division multiplexer; the transmission end of the local wavelength division multiplexer and the local Faraday magnetic rotation reflector are respectively connected with 2 ports on one side of the optical fiber coupler; the narrow linewidth laser and the 2 photoelectric detectors are respectively connected with the 3 ports on the other side of the optical fiber coupler;

the reflection end of the outgoing demultiplexer of the relay end first optical fiber interferometer is connected with the reflection end of the local wavelength division multiplexer of the relay end second interferometer;

the input end optical fiber coupler and the output end optical fiber coupler of the relay end first optical fiber interferometer and 2 photoelectric detectors of the relay end second interferometer are connected with the input end of a relay control circuit, the output end of the relay control circuit is connected with the control end of a relay phase compensation module, the relay phase compensation module is arranged in a measuring arm between the public end of a far-end wavelength division multiplexer of the relay end second interferometer and the public end of a local wavelength division multiplexer, or the relay phase compensation module is arranged in a measuring arm between the input end wavelength division multiplexer and the output end demultiplexer of the relay end first optical fiber interferometer;

the sum of an optical path L3 from the input optical fiber coupler of the first optical fiber interferometer at the relay end to the transmission end of the input optical fiber multiplexer of the first optical fiber interferometer at the relay end and an optical path L5 from the transmission end of the wavelength division multiplexer at the output end of the first optical fiber interferometer at the relay end to the output optical fiber coupler of the first optical fiber interferometer at the relay end is equal to the optical path of the reference arm of the first optical fiber interferometer at the relay end, namely, the optical path L6 from the other output port of the input optical fiber coupler to the other input port of the output optical fiber coupler, namely, the optical path L3+ L5 is equal to L6;

an optical path L2 of a reflection end of the incoming wavelength division multiplexer of the relay-end first optical fiber interferometer to a reflection end of a far-end wavelength division multiplexer of a michelson interferometer of the previous-stage optical fiber phase compensator is equal to an optical path L1 of a transmission end of the far-end wavelength division multiplexer of the michelson interferometer of the previous-stage optical fiber phase compensator to a far-end faraday magnetic rotating reflector of the michelson interferometer of the previous-stage optical fiber phase compensator, namely L1 is equal to L2;

an optical path L10 from the transmission end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to the far-end faraday magnetic rotating reflector is equal to an optical path L11 from the reflection end of the far-end wavelength division multiplexer of the relay-end second optical fiber interferometer to a service signal receiving end detector or an optical fiber phase compensator of the next-stage relay to the input-end wavelength division multiplexer of the first optical fiber interferometer, namely L10 is equal to L11.

6. The optical fiber phase compensator of a high precision optical fiber interferometer according to claim 5, wherein: the narrow linewidth laser of the relay-end first optical fiber interferometer consists of a 1 multiplied by 2 optical fiber coupler and an erbium-doped optical fiber amplifier; the input port of the 1 × 2 optical fiber coupler is connected with the transmission end of the far-end wavelength division multiplexer of the michelson interferometer of the first-stage optical fiber phase compensator, 2 output ports of the 1 × 2 optical fiber coupler are respectively connected with the input end of the erbium-doped optical fiber amplifier and the far-end faraday magnetic rotating reflector of the michelson interferometer of the last-stage optical fiber phase compensator, and the output end of the erbium-doped optical fiber amplifier forms the output end of the narrow-linewidth laser source.

7. The optical fiber phase compensator of a high precision optical fiber interferometer according to claim 5, wherein:

when the relay phase compensation module is arranged in a measuring arm between the public end of the remote wavelength division multiplexer of the relay end second interferometer and the public end of the local wavelength division multiplexer, the relay control circuit multiplies a phase drift detection value detected by the relay end first optical fiber interferometer by 2, sums the phase drift detection value with a phase drift detection value detected by the relay end second interferometer, and controls the relay phase compensation module to perform phase compensation;

when the relay phase compensation module is arranged in a measuring arm between the public end of the incoming-end wavelength division multiplexer and the public end of the outgoing-end demultiplexer of the relay-end first optical fiber interferometer, the relay control circuit divides a phase drift detection value detected by the relay-end second optical fiber interferometer by 2, sums the phase drift detection value detected by the relay-end first optical fiber interferometer and then controls the relay phase compensation module to perform phase compensation.