CN111934773B

CN111934773B - Distributed optical fiber broadband phase-stable transmission distribution system and method based on loop topology

Info

Publication number: CN111934773B
Application number: CN202010804747.8A
Authority: CN
Inventors: 张�浩
Original assignee: CETC 44 Research Institute
Current assignee: CETC 44 Research Institute
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2021-06-08
Anticipated expiration: 2040-08-12
Also published as: CN111934773A

Abstract

The invention discloses a distributed optical fiber broadband phase-stabilized transmission distribution system and a distributed optical fiber broadband phase-stabilized transmission distribution method based on loop topology, and the distributed optical fiber broadband phase-stabilized transmission distribution system comprises a broadband frequency source, an optical fiber frequency phase-stabilized transmission unit, N user units and M optical amplification units, wherein the optical fiber frequency phase-stabilized transmission unit, the N user units and the M optical amplification units are connected through optical fibers to form a single-fiber bidirectional serial loop topology access.

Description

Distributed optical fiber broadband phase-stable transmission distribution system and method based on loop topology

Technical Field

The invention relates to the technical field of fiber broadband transmission, in particular to a distributed fiber broadband phase-stable transmission distribution system and method based on loop topology.

Background

The high-precision frequency signal has important application value in the fields of satellite navigation, aerospace, deep space exploration, reconnaissance and early warning and the like. Optical fiber transmission has the advantages of low loss, large capacity, large bandwidth, high speed, high stability, safety and reliability, and has been widely applied in the field of communication. Fiber-based frequency transmission is an effective way to achieve higher precision frequency transmission and distribution, and continues to push the development of the microwave photon-related field. The high-precision optical fiber frequency stable phase transmission faces the problem that the transmission time delay of an optical fiber link changes along with the changes of factors such as temperature, stress, vibration, transmission wavelength and the like, and the frequency/phase of a transmission frequency signal is deteriorated; in a distributed frequency phase-stable transmission system, it is also not possible to ensure that each user node realizes phase synchronization/consistent frequency signal reception. For distributed frequency stationary phase transmission, a common method is to operate a plurality of sets of point-to-point frequency stationary phase transmission systems independently, but as the number of distributed nodes increases, the whole distributed transmission system becomes larger and larger, and the control becomes more and more complex. And the other method is that on a point-to-point frequency phase-stable transmission main link, part of forward and backward transmitted optical carrier signals are separated to obtain forward and backward transmitted frequency signals, and high-precision distributed optical fiber frequency transmission is realized through signal processing. This idea was first proposed in 2010 by the german PTB institute and gradually applied to fiber distributed frequency transmission.

Disclosure of Invention

The invention aims to solve the technical problem of providing a distributed optical fiber broadband phase-stable transmission distribution system and a distributed optical fiber broadband phase-stable transmission distribution method based on loop topology, which are suitable for the distributed phase-stable broadband signal transmission distribution of any frequency signal, have small volume and simple control of an optical fiber frequency phase-stable transmission unit, and enable the optical fiber frequency phase-stable transmission unit to independently complete the photoelectric conversion and signal processing work of the signal. In order to solve the above problems, the present invention provides a distributed optical fiber broadband phase-stable transmission distribution system based on a loop topology, including a broadband frequency source, an optical fiber frequency phase-stable transmission unit, N user units connected in series, and M optical amplification units connected in series, where the optical fiber frequency phase-stable transmission unit has a first port, a second port, and a third port, an output end of the broadband frequency source is connected with the first port of the optical fiber frequency phase-stable transmission unit, the second port of the optical fiber frequency phase-stable transmission unit is connected with the third port of the optical fiber frequency phase-stable transmission unit after passing through the N user units and the M optical amplification units in sequence, and the optical fiber frequency phase-stable transmission unit, the N user units, and the M optical amplification units are connected by optical fibers to form a single-fiber bidirectional serial loop topology path;

the broadband frequency source is used for outputting a broadband signal;

the optical fiber frequency phase-stabilizing transmission unit is used for generating a reference frequency signal, performing electro-optical conversion on the reference frequency signal, and then inputting the reference frequency signal into an optical fiber loop through a second port and a third port of the optical fiber frequency phase-stabilizing transmission unit respectively; the optical fiber frequency phase-stabilizing transmission unit acquires first time delay/phase information between a local reference signal and a return reference frequency signal, and stabilizes transmission time delay in an optical fiber loop according to the first time delay/phase information;

the user unit is used for receiving reference frequency signals output by the second port and the third port of the optical fiber frequency-stabilized phase transmission unit, acquiring second time delay/phase information between the two reference frequency signals, and receiving optical carrier broadband signals with stable phases according to the second time delay/phase information;

the optical amplification unit is used for amplifying the optical carrier broadband signal and the optical carrier reference frequency signal transmitted by the second port and the third port of the optical fiber frequency phase-stable transmission unit.

Further, the optical fiber frequency-phase-stable transmission unit includes a reference frequency source, a first control module, a first optical transmitting module, a second optical transmitting module, a first wavelength division multiplexing module, a first optical receiving module, a first delay/phase detection module, a third optical transmitting module, a second wavelength division multiplexing module, a second optical receiving module, and a first delay/phase compensation module;

the reference frequency source is used for providing a reference frequency signal and sending the reference frequency signal to the second optical transmitting module, the third optical transmitting module and the first time delay/phase detection module;

the first optical transmitting module is used for receiving a broadband signal output by a broadband frequency source, converting the broadband signal into an optical carrier broadband signal and transmitting the optical carrier broadband signal to the first wavelength division multiplexing module;

the second optical transmitting module is used for receiving a reference frequency signal sent by a reference frequency source, converting the reference frequency signal into an optical carrier reference frequency signal and transmitting the optical carrier reference frequency signal to the first wavelength division multiplexing module;

the first wavelength division multiplexing module is used for multiplexing an optical carrier broadband signal transmitted by the first optical transmitting module and an optical carrier reference frequency signal transmitted by the second optical transmitting module into an optical fiber, and transmitting an optical carrier frequency signal to the second wavelength division multiplexing module after sequentially passing through the optical amplifying unit and the user unit; meanwhile, the first wavelength division multiplexing module is also used for receiving the optical carrier reference frequency signal from the optical fiber loop, demultiplexing the optical carrier reference frequency signal and transmitting the optical carrier reference frequency signal to the first optical receiving module;

the first optical receiving module is used for performing photoelectric conversion on the optical carrier reference frequency signal transmitted by the first wavelength division multiplexing module and then transmitting the optical carrier reference frequency signal to the first time delay/phase detection module;

the third optical transmitting module is used for receiving a reference frequency signal sent by a reference frequency source, converting the reference frequency signal into an optical carrier reference frequency signal and transmitting the optical carrier reference frequency signal to the second wavelength division multiplexing module;

the second wavelength division multiplexing module is used for multiplexing the optical carrier reference frequency signal transmitted by the third optical transmitting module into an optical fiber, and transmitting the optical carrier reference frequency signal to the first wavelength division multiplexing module after sequentially passing through the first time delay/phase compensation module, the user unit and the optical amplification unit; meanwhile, the second wavelength division multiplexing module is also used for receiving the optical carrier reference frequency signal from the optical fiber loop, and transmitting the optical carrier reference frequency signal to the second optical receiving module after demultiplexing the optical carrier reference frequency signal;

the second optical receiving module is used for performing photoelectric conversion on the optical carrier reference frequency signal transmitted by the second wavelength division multiplexing module and then transmitting the optical carrier reference frequency signal to the first time delay/phase detection module;

the first time delay/phase detection module is used for acquiring the time delay/phase and the change information thereof of the optical fiber loop according to the reference frequency signals input by the reference frequency source, the first optical receiving module and the second optical receiving module, and inputting the time delay and the change information thereof into the control module;

the first control module is used for generating a control signal for stabilizing the transmission delay of the optical fiber loop according to the delay and the change information thereof and transmitting the control signal to the first delay/phase compensation module;

and the first time delay/phase compensation module is used for adjusting the transmission time delay of the whole optical fiber loop according to the control signal input by the first control module.

Furthermore, each subscriber unit comprises an optical coupler, a second control module, a third wavelength division multiplexing module, a first photoelectric conversion module, a second time delay/phase detection module, a fourth wavelength division multiplexing module, a second time delay/phase compensation module, a third time delay/phase compensation module and a second photoelectric module;

the optical coupler is used for coupling an optical carrier reference frequency signal and an optical carrier broadband signal transmitted by a third port of the optical fiber frequency phase-stabilizing transmission unit to the second time delay/phase compensation module, and simultaneously coupling the optical carrier reference frequency signal transmitted by the second port of the optical fiber frequency phase-stabilizing transmission unit to the third wavelength division multiplexing module;

the third wavelength division multiplexing module is used for inputting the optical carrier reference frequency signal from the optical coupler to the first photoelectric conversion module; the first photoelectric conversion module is used for performing photoelectric conversion on the received light-carried reference frequency signal and inputting the light-carried reference frequency signal into the second time delay/phase detection module;

the second time delay/phase compensation module receives the optical carrier reference frequency signal and the optical carrier broadband signal transmitted by the optical coupler, performs time delay/phase compensation on the optical carrier reference frequency signal and the optical carrier broadband signal according to a control signal generated by the second control module, and then outputs the compensated optical carrier frequency signal to the fourth wavelength division multiplexing module;

the fourth wavelength division multiplexing module is used for inputting the optical carrier reference frequency signal transmitted by the second time delay/phase compensation module to the third time delay/phase compensation module;

the third time delay/phase compensation module is used for receiving the control signal of the second control module, performing time delay/phase compensation on the optical carrier reference frequency signal transmitted by the fourth wavelength division multiplexing module according to the control signal, and outputting the compensated optical carrier reference frequency signal to the second photoelectric conversion module;

the second photoelectric conversion module is used for photoelectrically converting the optical carrier reference frequency signal from the third time delay/phase compensation module and outputting the converted optical carrier reference frequency signal to the second time delay/phase detection module;

the second time delay/phase detection module is used for receiving the reference frequency signals transmitted by the first photoelectric conversion module and the second photoelectric conversion module, acquiring relevant time delay/phase and change information thereof in an optical fiber loop between the subscriber unit and the optical fiber frequency phase-stabilizing transmission unit, and outputting the relevant time delay/phase and change information to the second control module;

the second control module is used for generating a corresponding control signal according to the time delay/phase and the change information thereof in the optical fiber loop acquired by the second time delay/phase detection module, and outputting the control signal to the second time delay/phase compensation module and the third time delay/phase compensation module.

Furthermore, the distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology further includes a third photoelectric conversion module, the fourth wavelength division multiplexing module of each subscriber unit is connected with the input end of the third photoelectric conversion module, and the output end of the third photoelectric conversion module is connected to the local subscriber, so as to provide a stable broadband signal for the local subscriber.

Further, the optical coupler is a 2 × 2 optical coupler, the optical coupler has a first port, a second port, a third port and a fourth port, the first port of the optical coupler is connected with the second port of the optical fiber frequency phase-stable transmission unit, the second port of the optical coupler is connected with the third port of the optical fiber frequency phase-stable transmission unit, the third port of the optical coupler is connected with the second delay/phase detection module, and the fourth port of the optical coupler is connected with the third wavelength division multiplexing module.

On the other hand, the invention also provides a distributed optical fiber broadband phase-stable transmission distribution method based on loop topology, which comprises the following steps:

s1: the broadband frequency source transmits the broadband signal to the optical fiber frequency phase-stable transmission unit;

s2: the optical fiber frequency phase-stabilizing transmission unit converts a broadband signal input by a broadband frequency source into an optical carrier broadband signal, and the optical carrier broadband signal is input into an optical fiber loop from a third port of the optical fiber frequency phase-stabilizing transmission unit after wavelength division multiplexing;

s3: the reference frequency source generates a reference frequency signal, the optical fiber frequency phase-stable transmission unit converts the reference frequency signal into an optical carrier reference frequency signal, and the optical carrier reference frequency signal is input into the optical fiber loop from a second port and a third port of the optical fiber frequency phase-stable transmission unit respectively after wavelength division multiplexing;

s4: the user unit acquires optical carrier broadband signals and optical carrier reference frequency signals transmitted by a second port and a third port of a part of optical fiber frequency phase-stable transmission units, and performs wavelength division demultiplexing and photoelectric conversion on the optical carrier broadband signals and the optical carrier reference frequency signals, and performs time delay/phase detection on the reference signals;

s5: the bidirectional optical amplification unit amplifies optical carrier broadband signals and optical carrier reference frequency signals sent by a second port and a third port of the optical fiber frequency phase-stabilized transmission unit;

s6: the optical fiber frequency phase-stable transmission unit receives an optical carrier reference frequency signal transmitted and returned from the optical fiber loop, and compares the optical carrier reference frequency signal after photoelectric conversion with a local reference frequency signal sent by a reference frequency source so as to obtain the time delay/phase and the change information of the optical fiber loop;

s7: the optical fiber frequency phase-stable transmission unit compensates the time delay/phase of the whole optical fiber loop according to the obtained time delay and the change information thereof so as to ensure that the transmission time delay of the optical fiber loop is constant;

s8: the user unit receives the optical carrier reference frequency signal transmitted by the second port and the optical carrier reference frequency signal transmitted by the third port of the optical fiber frequency phase-stable transmission unit, and obtains the time delay/phase and the change information of the optical fiber loop;

s9: and the subscriber units perform time delay/phase compensation on the received optical carrier signals according to the acquired time delay/phase and the variation information thereof so as to ensure that the broadband signals received by each subscriber unit have the characteristics of stable and consistent phase.

The invention has the beneficial effects that:

(1) the optical fiber frequency phase-stable transmission unit acquires time delay and phase information of the broadband frequency signal and compensates the time delay and the phase, so that the phase of the broadband frequency signal received by the user units is stable, and the phase of the broadband frequency received by each user unit can be kept synchronous;

(2) the optical fiber frequency phase-stabilizing transmission unit, the user unit and the bidirectional optical amplification unit are connected in series to form a single-fiber bidirectional series loop topological path, so that the system volume and the control process of the optical fiber frequency phase-stabilizing transmission unit are prevented from being large and complicated along with the increase of distribution nodes while the distributed optical fiber broadband frequency phase-stabilizing transmission is realized;

(3) a reference frequency source is arranged in the optical fiber frequency phase-stable transmission unit, and the sensing and extraction of time delay/phase information in an optical fiber loop are completed by a reference frequency signal generated by the reference frequency source, so that a broadband signal is not interfered by a transmission distribution system, and the form of the transmitted signal is not limited by the transmission distribution system;

(4) the optical fiber frequency stable phase transmission unit independently completes the photoelectric mutual conversion and signal processing of signals, and can effectively avoid the influence of environmental factors such as temperature on the use of photons and electronic devices, thereby further improving the performance of users for obtaining broadband frequency signals.

Drawings

Fig. 1 is a schematic structural diagram of a distributed optical fiber broadband phase-stable transmission distribution system based on a loop topology according to a preferred embodiment of the present invention.

Fig. 2 is a schematic structural diagram of an optical fiber frequency-stable phase transmission unit of the transmission system in fig. 1.

Fig. 3 is a schematic diagram of a subscriber unit of the transmission system of fig. 1.

Fig. 4 is a flowchart of a distributed optical fiber broadband phase-stable transmission distribution method based on a loop topology according to the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

In the description of the present invention, unless otherwise specified and limited, it is to be noted that the term "connected" is to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, or a communication between two elements, or may be a direct connection or an indirect connection through an intermediate medium, and a specific meaning of the term may be understood by those skilled in the art according to specific situations.

Example one

Fig. 1 is a schematic structural diagram of a distributed optical fiber broadband phase-stable transmission distribution system based on a loop topology according to a preferred embodiment of the present invention. The transmission system comprises a broadband frequency source 1, an optical fiber frequency stationary phase transmission unit 2, a subscriber unit 3 of N series connections and an optical amplification unit 4 of M series connections, wherein the optical fiber frequency stationary phase transmission unit 2 is provided with a first port, a second port and a third port, the output end of the broadband frequency source 1 is connected with the first port of the optical fiber frequency stationary phase transmission unit 2, the second port of the optical fiber frequency stationary phase transmission unit 2 is sequentially connected with the third port of the optical fiber frequency stationary phase transmission unit 2 through the N subscriber units 3 and the M optical amplification units 4, and the optical fiber frequency stationary phase transmission unit 2, the N subscriber units 3 and the M optical amplification units 4 are connected through optical fibers to form a single-fiber bidirectional serial loop topological path.

The broadband frequency source 1 is used for outputting a broadband signal.

The optical fiber frequency phase-stabilized transmission unit 2 is configured to generate a reference frequency signal, convert the reference frequency signal into an optical carrier reference frequency signal, and input the optical carrier reference frequency signal into an optical fiber loop through a second port and a third port of the optical fiber frequency phase-stabilized transmission unit 2, and convert a broadband signal from the broadband frequency source 1 into an optical carrier broadband signal, where the optical carrier broadband signal is input into the optical fiber loop from the third port of the optical fiber frequency phase-stabilized transmission unit 2. The optical carrier reference frequency signal output by the second port of the optical fiber frequency phase-stable transmission unit 2 sequentially passes through the N user units 3 and the M optical amplification units 4 and then returns to the optical fiber frequency phase-stable transmission unit 2 from the third port of the optical fiber frequency phase-stable transmission unit 2; meanwhile, the optical carrier broadband signal and the optical carrier reference frequency signal output by the third port of the optical fiber frequency phase-stable transmission unit 2 sequentially pass through the M optical amplification units 4 and the N user units 3 and then return to the optical fiber frequency phase-stable transmission unit from the second port of the optical fiber frequency phase-stable transmission unit 2. The optical fiber frequency phase-stable transmission unit 2 receives the optical carrier reference frequency signals returned from the second port and the third port, compares the returned reference frequency with the local reference frequency signal, obtains a first time delay information in the optical fiber loop at the moment, and stabilizes the transmission time delay of the optical fiber loop according to the first time delay information.

The subscriber unit 3 is configured to receive the optical carrier broadband signal and the optical carrier reference frequency signal transmitted by the second port and the third port of the optical fiber frequency-stabilized phase transmission unit 2, compare the optical carrier reference frequency signals transmitted by the two ports after photoelectric conversion, obtain a second time delay information in the optical fiber loop at this time, and receive the optical carrier broadband signal with a stable phase according to the second time delay information.

The optical amplification unit 4 is configured to amplify the optical carrier broadband signal and the optical carrier reference frequency signal transmitted by the second port and the third port of the optical fiber frequency-stabilized phase transmission unit 2.

As shown in fig. 2, the optical fiber frequency-stable phase transmission unit 2 includes a reference frequency source 201, a first control module 202, a first optical emitting module 203, a second optical emitting module 204, a first wavelength division multiplexing module 205, a first optical receiving module 206, a first delay/phase detecting module 207, a third optical emitting module 208, a second wavelength division multiplexing module 209, a second optical receiving module 210, and a first delay/phase compensating module 211. The output end of the broadband frequency source 201 is connected to the input ends of the second optical module 204, the first delay/phase detection module 207 and the third optical module 208, the input end of the first optical module 203 is connected to the output end of the broadband frequency source 1, the output ends of the first optical module 203 and the second optical module 204 are connected to the input end of the first wavelength division multiplexing module 205, the output end of the first wavelength division multiplexing module 205 is connected to the input end of the first delay/phase detection module 207 via the first optical receiving module 206, the output end of the third optical module 208 is connected to the input end of the second wavelength division multiplexing module 209, the output end of the second wavelength division multiplexing module 209 is connected to the input end of the first delay/phase detection module 207 via the second optical receiving module 210, the output end of the first delay/phase detection module 207 is connected to the input end of the first control module 202, the output end of the first control module 202 is connected to the input end of the first delay/phase compensation module 211, and the first delay/phase compensation module 211 is further connected to the second wavelength division multiplexing module 209.

The reference frequency source 201 provides a reference frequency signal and transmits the reference frequency signal to the second optical transceiver module 204, the first delay/phase detection module 207, and the third optical transceiver module 208, respectively.

The first optical transceiver module 203 receives the broadband signal output by the broadband frequency source 1, converts the broadband signal into an optical carrier broadband signal, and transmits the optical carrier broadband signal to the first wdm module 205, and the second optical transceiver module 204 receives the reference frequency signal output by the reference frequency source 201, converts the reference frequency signal into an optical carrier reference frequency signal, and transmits the optical carrier reference frequency signal to the first wdm module 205. The first wavelength division multiplexing module 205 multiplexes the optical carrier broadband signal transmitted by the first optical transceiver module 203 and the optical carrier reference frequency signal transmitted by the second optical transceiver module 204 into one optical fiber, and the optical carrier broadband signal and the optical carrier reference frequency signal sequentially pass through the M optical amplification units 4 and the N subscriber units 3 and are then transmitted to the second wavelength division multiplexing module 209; meanwhile, the first wavelength division multiplexing module 205 demultiplexes the reference frequency signal on optical carrier transmitted to the optical fiber loop from the second wavelength division multiplexing module 209 and transmits the demultiplexed reference frequency signal to the first optical receiving module 206. The first optical receiving module 206 photoelectrically converts the optical carrier reference frequency signal transmitted by the first wavelength division multiplexing module 205 and transmits the converted signal to the first delay/phase detection module 207.

The third optical transceiver module 208 receives the reference frequency signal output by the reference frequency source 201, converts the reference frequency signal into an optical carrier reference frequency signal, and transmits the optical carrier reference frequency signal to the second wavelength division multiplexing module 209. The second wavelength division multiplexing module 209 multiplexes the optical carrier reference frequency signal transmitted by the third optical transmitting module 208 into one optical fiber, and the optical carrier reference frequency signal is transmitted to the first wavelength division multiplexing module 205 after passing through the first delay/phase compensation module 211, the N subscriber units 3, and the M optical amplification units 4 in sequence; meanwhile, the second wavelength division multiplexing module 209 demultiplexes the reference frequency signal on optical carrier transmitted to the optical fiber loop from the first wavelength division multiplexing module 205 and transmits the demultiplexed reference frequency signal to the second optical receiving module 210. The second optical receiving module 210 photoelectrically converts the optical carrier reference frequency signal transmitted by the second wavelength division multiplexing module 209 and transmits the converted signal to the first delay/phase detection module 207.

The first delay/phase detection module 207 receives a local reference frequency signal output by the reference frequency source 201, compares the local reference frequency signal with reference frequency signals input by the first optical receiving module 206 and the second optical receiving module 210 to obtain a delay and change information thereof in the optical fiber loop, and inputs the delay and change information thereof to the control module.

The first control module 202 receives the time delay and the variation information thereof in the optical fiber loop acquired by the first time delay/phase detection module 207, generates a control signal for stabilizing the transmission time delay of the optical fiber loop, and transmits the control signal to the first time delay/phase compensation module 211. The first delay/phase compensation module 211 adjusts the transmission delay of the entire optical fiber loop according to the control signal input by the first control module 202, so as to ensure that the transmission delay of the optical fiber loop is constant.

As shown in fig. 3, each subscriber unit 3 includes an optical coupler 301, a second control module 302, a third wavelength division multiplexing module 303, a first photoelectric conversion module 304, a second delay/phase detection module 305, a second delay/phase compensation module 306, a fourth wavelength division multiplexing module 307, a third delay/phase compensation module 308, and a second photoelectric conversion module 309. The optical coupler 301 is a 2 × 2 optical coupler, and the optical coupler 301 has a first port, a second port, a third port, and a fourth port; a first port of the optical coupler 301 is connected with a second port of the optical fiber frequency phase-stable transmission unit 2, and a second port of the optical coupler 301 is connected with a third port of the optical fiber frequency phase-stable transmission unit 2, and is used for accessing an optical carrier broadband signal and an optical carrier reference frequency signal in an optical fiber loop to the subscriber unit 3; a third port of the optical coupler 301 sequentially passes through the second delay/phase compensation module 306, the fourth wavelength division multiplexing module 307, the third delay/phase compensation module 308, and the second photoelectric conversion module 309 to be connected to an input end of the second delay/phase detection module 305, a fourth port of the optical coupler 301 sequentially passes through the third wavelength division multiplexing module 303 and the first photoelectric conversion module 304 to be connected to an input end of the second delay/phase detection module 305, an output end of the second delay/phase detection module 305 is connected to an input end of the second control module 302, and an output end of the second control module 302 is connected to input ends of the second delay/phase compensation module 306 and the third delay/phase compensation module 308.

The first port of the optical coupler 301 receives the reference frequency signal of the optical carrier transmitted from the second port of the fiber frequency phase-stabilized transmission unit 2 in the fiber loop, and couples part of the reference frequency signal of the optical carrier to the third wdm module 303, and the second port of the optical coupler 301 receives the reference frequency signal of the optical carrier and the wideband signal of the optical carrier transmitted from the third port of the fiber frequency phase-stabilized transmission unit 2 in the fiber loop, and couples part of the reference frequency signal of the optical carrier and the wideband signal of the optical carrier to the second delay/phase compensation module 306.

The third wavelength division multiplexing module 303 transmits the optical carrier reference frequency signal from the fourth port of the optical coupler 301 to the first photoelectric conversion module 304; the first photoelectric conversion module 304 performs photoelectric conversion on the received optical carrier reference frequency signal and transmits the converted optical carrier reference frequency signal to the second delay/phase detection module 305.

The second delay/phase detection module 305 obtains the delay/phase of the broadband signal in the optical fiber loop and the variation information thereof according to the reference frequency signals from the first photoelectric conversion module 304 and the second photoelectric conversion module 309, and outputs the delay/phase and the variation information to the second control module 302.

The second control module 302 generates a control signal according to the delay and its variation information transmitted by the second delay/phase detection module 305, and inputs the control signal to the second delay/phase compensation module 306 and the third delay/phase compensation module 308.

The second delay/phase compensation module 306 receives the optical carrier frequency signal transmitted by the third port of the optical coupler 301, performs delay/phase compensation on the optical carrier frequency signal according to the control signal generated by the second control module 302, and then transmits the compensated optical carrier frequency signal to the fourth wavelength division multiplexing module 307; the fourth wavelength division multiplexing module 307 transmits the optical carrier reference frequency signal transmitted by the second delay/phase compensation module 307 to the third delay/phase compensation module 308; the third delay/phase compensation module 308 performs delay/phase compensation on the optical carrier reference frequency signal transmitted by the fourth wavelength division multiplexing module according to the control signal of the second control module, and then transmits the compensated optical carrier reference frequency signal to the second photoelectric conversion module 309; the second photoelectric conversion module 309 photoelectrically converts the optical carrier reference frequency signal from the third delay/phase compensation module 308 and transmits the converted signal to the second delay/phase detection module 305.

The distributed optical fiber broadband phase-stable transmission and distribution system based on the loop topology further comprises a third photoelectric conversion module 5, a fourth wavelength division multiplexing module 307 of each subscriber unit 3 is connected with an input end of the third photoelectric conversion module 5, and an output end of the third photoelectric conversion module 5 is connected to a local subscriber, so that a stable broadband signal is provided for the local subscriber.

Example two

As shown in fig. 4, it is a flowchart of a distributed optical fiber broadband phase-stable transmission distribution method based on a loop topology, and specifically includes the following steps:

in this embodiment, the wavelength of the reference frequency signal transmitted to the optical fiber loop from the second port of the optical fiber frequency phase-stable transmission unit 2 is 1551.72nm, the wavelength of the broadband signal transmitted to the optical fiber loop from the third port of the optical fiber frequency phase-stable transmission unit 2 is 1550.12nm, the wavelength of the reference frequency signal is 1548.52nm, the broadband signal to be transmitted is any bandwidth frequency signal between 10 GHz and 18GHz, and the frequency of the reference frequency signal is 1 GHz. The 2 × 2 optical coupler used in the subscriber unit 3 has a coupling ratio of 20: 80.

s1: the broadband frequency source 1 transmits a broadband signal to the fiber frequency phase-stable transmission unit 2.

S2: the fiber frequency phase-stable transmission unit 2 converts the broadband signal input by the broadband frequency source 1 into an optical carrier broadband signal, and the optical carrier broadband signal is input into the fiber loop from the third port of the fiber frequency phase-stable transmission unit 2 after wavelength division multiplexing.

In this embodiment, the arbitrary dot frequency signal transmitted by the wideband frequency source 1 can be expressed as:

A₁＝cos(ωt+φ₀) (1)

wherein: omega is the frequency of the broadband signal, phi₀Is the initial phase of the wideband signal.

The first optical transceiver module 203 receives the broadband signal from the broadband frequency source 1, converts the broadband signal into an optical carrier broadband signal, and transmits the optical carrier broadband signal to the first wdm module 205; the optical broadband signal is multiplexed into an optical fiber by the first wdm module 205 and then input into an optical fiber loop, and sequentially passes through the optical amplification unit 4 and the subscriber unit 3 and then input into the second wdm module 209. S3: the reference frequency source 201 generates a reference frequency signal, the fiber frequency-stabilized transmission unit 2 converts the reference frequency signal into an optical carrier reference frequency signal, and the optical carrier reference frequency signal is input into the fiber loop from the second port and the third port of the fiber frequency-stabilized transmission unit 2 respectively after wavelength division multiplexing.

In this embodiment, the reference frequency signal is represented as:

wherein: omega₀Is the frequency of the reference frequency signal and,

is the initial phase of the reference frequency signal.

After the reference frequency source 201 sends a reference frequency signal, the second optical transceiver module 204 receives the reference frequency signal, converts the reference frequency signal into an optical carrier reference frequency signal, and transmits the optical carrier reference frequency signal to the first wavelength division multiplexing module 205, where the optical carrier reference frequency signal is multiplexed into one optical fiber by the first wavelength division multiplexing module 205, input into an optical fiber loop, and sequentially input into the second wavelength division multiplexing module 209 through the optical amplification unit 4 and the user unit 3; meanwhile, the third optical transceiver module 208 receives the reference frequency signal, converts the reference frequency signal into an optical carrier reference frequency signal, and transmits the optical carrier reference frequency signal to the second wavelength division multiplexing module 209, where the optical carrier reference frequency signal is multiplexed into one optical fiber by the second wavelength division multiplexing module 209, and then input into an optical fiber loop by the first delay/phase compensation module 211, and then input into the first wavelength division multiplexing module 205 after sequentially passing through the subscriber unit 3 and the optical amplification unit 4.

S4: the subscriber unit 3 obtains the optical carrier broadband signal and the optical carrier reference frequency signal transmitted by the second port and the third port of the partial optical fiber frequency phase-stable transmission unit, and performs wavelength division demultiplexing and photoelectric conversion on the optical carrier reference frequency signal and then performs delay/phase detection.

The optical carrier reference frequency signal output by the second port of the optical fiber frequency-stabilized phase transmission unit 2 enters the optical coupler 301 from the first port of the optical coupler 301, the optical coupler 301 splits the optical carrier reference frequency signal and couples a part of the optical carrier reference frequency signal to the third wavelength division multiplexing module 303 through the fourth port of the optical coupler 301, and the first photoelectric conversion module 304 converts the optical carrier reference frequency signal into an electrical signal and transmits the electrical signal to the second delay/phase detection module 305.

The reference frequency signal on the optical carrier transmitted by the second port of the fiber frequency phase-stable transmission unit 2 acquired by the ith subscriber unit 3 is represented as:

wherein: tau is_FUIs the transmission delay of the optical fiber loop from the second port of the optical fiber frequency-stabilized transmission unit 2 to the i (i ═ 1,2,3 … … N) th subscriber unit 3.

The optical carrier broadband signal and the optical carrier reference frequency signal output by the third port of the optical fiber frequency-stabilized phase transmission unit 2 enter the optical coupler 301 from the second port of the optical coupler 301, the optical coupler 301 splits the optical carrier broadband signal and the optical carrier reference frequency signal, and couples part of the optical carrier broadband signal and the optical carrier reference frequency signal to the second delay/phase compensation module 306 through the third port of the optical coupler 301, the second delay/phase compensation module 306 transmits the optical carrier reference frequency signal to the second photoelectric conversion module 309 through the fourth wavelength division multiplexing module 307 and the third delay/phase compensation module 308 in sequence, and the second photoelectric conversion module 309 converts the optical carrier reference signal into an electrical signal and transmits the electrical signal to the second delay/phase detection module 305.

The optical broadband signal carried by the optical fiber transmitted by the third port of the fiber frequency-stabilized phase-locked transmission unit 2 acquired by the ith subscriber unit 3 can be represented as:

A₄＝cos[ω(t-τ_BU-τ_d)+φ₀] (4)

wherein: tau is_BUIs the transmission delay of the optical fiber loop from the third port of the optical fiber frequency-stabilized transmission unit 2 to the ith (i ═ 1,2,3 … … N) subscriber unit 3; tau is_dAdditional delay for the delay compensation module.

The reference frequency signal on optical carrier transmitted by the third port of the fiber frequency phase-stable transmission unit 2 acquired by the ith subscriber unit 3 can be represented as:

s5: the bidirectional optical amplifying unit 4 amplifies the optical carrier reference frequency signal transmitted by the second port and the optical carrier broadband signal and the optical carrier reference frequency signal transmitted by the third port of the optical fiber frequency phase-stabilized transmission unit 2.

S6: the optical fiber frequency phase-stable transmission unit 2 receives an optical carrier reference frequency signal transmitted and returned from the optical fiber loop, and compares the reference frequency signal after photoelectric conversion with a local reference frequency signal sent by a reference frequency source 201, so as to obtain the time delay/phase and the change information of the optical fiber loop.

In the optical fiber loop, the optical carrier reference frequency signal output by the second port of the optical fiber frequency phase-stabilized transmission unit 2, and the optical carrier broadband signal and the optical carrier reference frequency signal output by the third port return to the optical fiber frequency phase-stabilized transmission unit 2 through the first wavelength division multiplexing module 205 and the second wavelength division multiplexing module 209, the first wavelength division multiplexing module 205 demultiplexes the returned optical carrier reference frequency signal and transmits the demultiplexed optical carrier reference frequency signal to the first optical receiving module 206, the first optical receiving module 206 converts the optical carrier reference frequency signal into an electrical signal and transmits the electrical signal to the first delay/phase detection module 207, the second wavelength division multiplexing module 209 transmits the returned optical carrier reference frequency signal to the second optical receiving module 210, the second optical receiving module 210 converts the optical carrier reference frequency signal into an electrical signal and transmits the electrical signal to the first delay/phase detection module 207, and the first delay/phase detection module 207 transmits the broadband signal transmitted by the first optical receiving module 206 and the second optical receiving module 210 And comparing the reference frequency signal with a local reference frequency signal sent by the reference frequency source 201, and obtaining the time delay/phase and the change information thereof in the optical fiber loop.

The optical carrier reference frequency signals received by the second port and the third port of the fiber frequency phase-stable transmission unit 2 are expressed as follows:

s7: the optical fiber frequency phase-stable transmission unit 2 compensates the time delay/phase of the whole optical fiber loop according to the obtained time delay/phase and the change information thereof, so as to ensure that the transmission time delay of the optical fiber loop is constant. The propagation delay of the optical fiber loop can be expressed as:

τ_FU+τ_BU＝c (7)

wherein: c is a constant.

The first delay/phase detection module 207 transmits the acquired delay/phase and the variation information thereof to the first control module 202, the first control module 202 generates a corresponding control signal according to equation (7) and transmits the control signal to the first delay/phase compensation module 211, and the first delay/phase compensation module 211 compensates the transmission delay of the entire optical fiber loop according to the control signal to stabilize the transmission delay in the optical fiber loop, so that the transmission delay of the optical fiber loop is kept constant.

S8: the subscriber unit 3 receives the optical carrier reference frequency signal transmitted from the second port and the optical carrier reference frequency signal transmitted from the third port of the optical fiber frequency phase-stable transmission unit 2, and obtains the time delay/phase and the change information of the optical fiber loop.

On the premise that the transmission delay in the optical fiber loop is stable, the second delay/phase detection module 305 obtains the relevant transmission delay and the change information thereof in the optical fiber loop according to the reference frequency signals transmitted by the first photoelectric conversion module 304 and the second photoelectric conversion module 309.

S9: the subscriber units 3 perform delay/phase compensation on the received broadband signals according to the obtained delay/phase and the variation information thereof, so as to ensure that the broadband signals received by each subscriber unit 3 have the characteristics of phase stability and synchronization.

The second delay/phase detection module transmits the obtained delay and the change information thereof to the second control module 302, the second control module 302 generates a corresponding control signal according to the formula (8) and transmits the corresponding control signal to the second delay/phase compensation module 306 and the third delay/phase compensation module 308, the second delay/phase compensation module 306 compensates the broadband signal according to the control signal so as to transmit the broadband signal with stable transmission delay to the third photoelectric conversion module 5, and the third photoelectric conversion module 5 performs photoelectric conversion on the broadband signal and transmits the broadband signal to each local user.

τ_FU-τ_BU-2τ_d＝k (8)

Wherein: k is a constant.

When both of equations (7) and (8) are satisfied, the wideband signal that each subscriber unit 3 can output is obtained as:

in particular, when the following expression (10) is satisfied, the broadband signal output by the subscriber unit 3 has a phase synchronization characteristic.

Fig. 4 shows a flow chart of a distributed optical fiber broadband phase-stable transmission distribution method based on a loop topology, which specifically includes the following steps:

the difference between the present embodiment and the second embodiment is that the broadband signal transmitted by the broadband frequency source in the present embodiment is a pulse frequency sweeping signal, and the working principle of the present embodiment is the same as that of the second embodiment. The difference is that the embodiment implements broadband phase-stable transmission by phase measurement, and the embodiment implements broadband phase-stable transmission by delay measurement. In this embodiment, the wavelength of the reference frequency signal transmitted to the optical fiber loop from the second port of the optical fiber frequency phase-stable transmission unit 2 is 1551.72nm, the wavelength of the broadband signal transmitted to the optical fiber loop from the third port of the optical fiber frequency phase-stable transmission unit 2 is 1550.12nm, the wavelength of the reference frequency signal is 1548.52nm, the broadband signal to be transmitted is a pulse frequency sweep signal with an instantaneous bandwidth of 5GHz, and the frequency of the reference frequency signal is 1 GHz. The 2 × 2 optical coupler used in the subscriber unit 3 has a coupling ratio of 20: 80.

In this embodiment, the wideband signal sent by the wideband frequency source 1 is a pulse frequency sweep signal, which can be expressed as:

A₁'＝∑cos(ω't+φ₀') (1')

wherein: ω' is the frequency of the broadband signal,

is the initial phase of the wideband signal.

In this embodiment, the reference frequency signal is represented as:

wherein: omega₀' is the frequency of the reference frequency signal,

is the initial phase of the reference frequency signal.

wherein: tau is_FU'Is the transmission delay of the optical fiber loop from the second port of the optical fiber frequency-stabilized transmission unit 2 to the i '(i' is 1,2,3 … … N) th subscriber unit 3.

A₄′＝∑cos[ω′(t-τ_BU′-τ_d′)+φ′₀] (4')

wherein: tau is_BU'Is the transmission delay of the fiber loop from the third port of the fiber frequency-stabilized transmission unit 2 to the i' (i ═ 1,2,3 … … N) th subscriber unit 3; tau is_d"is the additional delay of the delay compensation module.

The reference frequency signal on optical carrier transmitted by the third port of the fiber frequency phase-stable transmission unit 2 acquired by the ith' subscriber unit 3 can be represented as:

In the optical fiber loop, the optical carrier reference frequency signal output by the second port of the optical fiber frequency-stabilized phase transmission unit 2, and the optical carrier broadband signal and the optical carrier reference frequency signal output by the third port return to the optical fiber frequency-stabilized phase transmission unit 2 through the first wavelength division multiplexing module 205 and the second wavelength division multiplexing module 209, the first wavelength division multiplexing module 205 demultiplexes the returned optical carrier reference frequency signal and transmits the demultiplexed optical carrier reference frequency signal to the first optical receiving module 206, the first optical receiving module 206 converts the optical carrier reference frequency signal into an electrical signal and transmits the electrical signal to the first delay/phase detection module 207, the second wavelength division multiplexing module 209 transmits the returned optical carrier reference frequency signal to the second optical receiving module 210, the second optical receiving module 210 converts the optical carrier reference frequency signal into an electrical signal and transmits the electrical signal to the first delay/phase detection module 207, and the first delay/phase detection module 207 transmits the reference frequency signal transmitted by the first optical receiving module 206 and the second optical receiving module 210 The signal is compared with a local reference frequency signal sent by the reference frequency source 201, and the time delay/phase and the change information thereof in the optical fiber loop are obtained.

τ_FU'+τ_BU'＝c (7')

wherein: c is a constant.

The first delay/phase detection module 207 transmits the acquired delay/phase and the variation information thereof to the first control module 202, the first control module 202 generates a corresponding control signal according to equation (7') and transmits the control signal to the first delay/phase compensation module 211, and the first delay/phase compensation module 211 compensates the transmission delay of the entire optical fiber loop according to the control signal to stabilize the transmission delay in the optical fiber loop, so that the transmission delay of the optical fiber loop is kept constant.

The second delay/phase detection module transmits the obtained delay and the change information thereof to the second control module 302, the second control module 302 generates a corresponding control signal according to the following formula (8') and transmits the corresponding control signal to the second delay/phase compensation module 306 and the third delay/phase compensation module 308, the second delay/phase compensation module 306 compensates the broadband signal according to the control signal to transmit the broadband signal with stable transmission delay to the third photoelectric conversion module 5, and the third photoelectric conversion module 5 performs photoelectric conversion on the broadband signal and transmits the broadband signal to each local user.

τ_FU'-τ_BU'-2τ_d'＝k (8')

Wherein: k is a constant.

When both the equations (7') and (8') are satisfied, the wideband signal that can be output by each subscriber unit 3 is obtained as:

in particular, when the following expression (10') is established, the broadband signal output from the subscriber unit 3 has a phase synchronization characteristic.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent structures made by using the contents of the present specification and the drawings can be directly or indirectly applied to other related technical fields, and are within the scope of the present invention.

Claims

1. A distributed optical fiber broadband phase-stable transmission distribution system based on loop topology is characterized in that: the broadband optical fiber frequency and phase stabilizing transmission system comprises a broadband frequency source, an optical fiber frequency and phase stabilizing transmission unit, N user units connected in series and M optical amplification units connected in series, wherein the optical fiber frequency and phase stabilizing transmission unit is provided with a first port, a second port and a third port, the output end of the broadband frequency source is connected with the first port of the optical fiber frequency and phase stabilizing transmission unit, the second port of the optical fiber frequency and phase stabilizing transmission unit sequentially passes through the N user units and the M optical amplification units and then is connected with the third port of the optical fiber frequency and phase stabilizing transmission unit, and the optical fiber frequency and phase stabilizing transmission unit, the N user units and the M optical amplification units are connected through optical fibers to form a single-fiber bidirectional serial loop topological passage;

the broadband frequency source is used for outputting a broadband signal;

the user unit is used for receiving optical carrier reference frequency signals output by the second port and the third port of the optical fiber frequency-stabilized phase transmission unit, acquiring second time delay/phase information between the two optical carrier reference frequency signals, and receiving optical carrier broadband signals with stable phases according to the second time delay/phase information;

2. The distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology, according to claim 1, wherein: the optical fiber frequency phase-stable transmission unit comprises a reference frequency source, a first control module, a first optical transmitting module, a second optical transmitting module, a first wavelength division multiplexing module, a first optical receiving module, a first time delay/phase detection module, a third optical transmitting module, a second wavelength division multiplexing module, a second optical receiving module and a first time delay/phase compensation module;

3. The distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology, according to claim 1, wherein: each subscriber unit comprises an optical coupler, a second control module, a third wavelength division multiplexing module, a first photoelectric conversion module, a second time delay/phase detection module, a fourth wavelength division multiplexing module, a second time delay/phase compensation module, a third time delay/phase compensation module and a second photoelectric conversion module;

the optical coupler is used for coupling the optical carrier reference frequency signal transmitted by the third port of the part of the optical fiber frequency phase-stable transmission unit to the second time delay/phase compensation module, and simultaneously coupling the optical carrier reference frequency signal and the optical carrier broadband signal transmitted by the second port of the part of the optical fiber frequency phase-stable transmission unit to the third wavelength division multiplexing module;

the third wavelength division multiplexing module is used for inputting the optical carrier reference frequency signal from the optical coupler to the first photoelectric conversion module;

the first photoelectric conversion module is used for performing photoelectric conversion on the received light-carried reference frequency signal and inputting the light-carried reference frequency signal into the second time delay/phase detection module;

the second time delay/phase compensation module receives the optical carrier reference frequency signal and the optical carrier broadband signal transmitted by the optical coupler, performs time delay/phase compensation on the optical carrier reference frequency signal and the optical carrier broadband signal according to a control signal generated by the second control module, and outputs the compensated optical carrier reference frequency signal and the compensated optical carrier broadband signal to the fourth wavelength division multiplexing module;

4. The distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology, according to claim 3, wherein: the distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology further comprises a third photoelectric conversion module, a fourth wavelength division multiplexing module of each subscriber unit is connected with the input end of the third photoelectric conversion module, and the output end of the third photoelectric conversion module is connected to a local user to provide a stable broadband signal for the local user.

5. The distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology, according to claim 3, wherein: the optical coupler is a 2 x 2 optical coupler, the optical coupler is provided with a first port, a second port, a third port and a fourth port, the first port of the optical coupler is connected with the second port of the optical fiber frequency phase-stable transmission unit, the second port of the optical coupler is connected with the third port of the optical fiber frequency phase-stable transmission unit, the third port of the optical coupler is connected with the second time delay/phase detection module, and the fourth port of the optical coupler is connected with the third wavelength division multiplexing module.

6. A distributed optical fiber broadband phase-stable transmission distribution method based on a loop topology, comprising the distributed optical fiber broadband phase-stable transmission distribution system based on the loop topology as claimed in any one of claims 1 to 5, characterized by comprising the following steps:

s7: the optical fiber frequency phase-stable transmission unit compensates the time delay/phase of the whole optical fiber loop according to the obtained time delay and the change information thereof so as to realize the constant transmission time delay of the optical fiber loop;

s9: and the subscriber units perform time delay/phase compensation on the received optical carrier signals according to the acquired time delay/phase and the variation information thereof so as to realize that the broadband signals received by each subscriber unit have the characteristics of stable and consistent phase.