CN108259091B

CN108259091B - Time domain filtering device method and device

Info

Publication number: CN108259091B
Application number: CN201611248519.7A
Authority: CN
Inventors: 陆亮亮; 梁文烨
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-12-29
Filing date: 2016-12-29
Publication date: 2020-02-14
Anticipated expiration: 2036-12-29
Also published as: CN108259091A

Abstract

The embodiment of the invention relates to the field of communication, in particular to a time domain filtering device and a time domain filtering device, which are used for realizing the effect that the phase modulation of first signal light is irrelevant to the polarization of pulse pump light. In the embodiment of the present invention, the phase of the first signal light is subjected to first phase modulation by the pulsed pump light, the polarization of the first signal light subjected to the first phase modulation is rotated by 90 degrees, the phase of the first signal light subjected to the first phase modulation and polarization rotation is subjected to second phase modulation by the pulsed pump light, and the first signal light subjected to the polarization rotation and the second phase modulation and the second signal light not subjected to the phase modulation are transmitted to the first port. The first signal light after the first phase modulation is rotated by 90 degrees in polarization and then is subjected to the second phase modulation by the pulse pump light, so that the effect that the phase modulation of the first signal light is independent of the polarization of the pulse pump light is realized.

Description

Time domain filtering device method and device

Technical Field

The embodiment of the invention relates to the field of communication, in particular to a time domain filtering device and a time domain filtering method.

Background

An optical switch is a device that switches an optical signal of one optical channel to another optical channel as required. The optical switch can directly exchange optical paths, is a core device for completing all-optical switching in an optical network, and the research of the optical switch increasingly becomes the focus of attention in the field of all-optical communication along with the expansion of the market of all-optical networks.

Fig. 1 exemplarily shows a structural schematic diagram of a time-domain filtering optical switch provided in the prior art, as shown in fig. 1, a beam of light enters a 3dB optical coupler 103 through a port 101, the beam of light passes through the 3dB optical coupler 103 and then is divided into two beams, and the two beams of light enter a Sagnac (Sagnac) ring 104 from left and right directions respectively, that is, the two beams of light are transmitted in a clockwise direction and a counterclockwise direction, optical paths of two light transmitted in opposite directions are always equal in an optical fiber, and interference occurs in the 3dB optical coupler after the two beams of light are finally operated for one circle. If the phase difference between the clockwise transmitted light and the counterclockwise transmitted light is 0, the interfered light beams will be emitted along the direction of the port 101, and the Sagnac loop will function as a mirror. If the phase difference between the clockwise transmitted light and the counterclockwise transmitted light is pi, the interfered light beam will exit from the direction of the port 102. If the phase difference between the clockwise transmitted light and the counterclockwise transmitted light is between 0 and pi, both the port 101 and the port 102 will have light to emit, and the specific outgoing beam splitting ratio is determined by the phase difference.

In the prior art, a strong pump light beam is generally subjected to cross-phase modulation with clockwise transmission light or anticlockwise transmission light in a Sagnac loop, so that nonlinear phase shift is generated, and a phase difference is formed between the clockwise transmission light and the anticlockwise transmission light.

However, in the above scheme, since the nonlinear phase shift is related to polarization, that is, the polarization of the pump light has an influence on the phase difference between the clockwise transmitted light and the counterclockwise transmitted light, it is difficult to obtain an accurate phase difference between the clockwise transmitted light and the counterclockwise transmitted light by the nonlinear phase shift of the pump light.

Disclosure of Invention

Embodiments of the present invention provide a time-domain filtering apparatus and method, which are used to achieve an effect that phase modulation of first signal light is independent of polarization of pulse pump light, so as to more accurately obtain a phase difference between the first signal light and second signal light.

The embodiment of the invention provides a time domain filtering device, which comprises a coupling unit and a processing unit, wherein the processing unit is connected with the coupling unit; a pulse pump light generating unit connected with the processing unit; the coupling unit includes a first port and a second port. The coupling unit is used for receiving the signal light, dividing the signal light into first signal light and second signal light, and sending the first signal light to the processing unit; under the condition of receiving the first signal light which is transmitted by the processing unit and has the polarization rotation and the second phase modulation, transmitting the first signal light which has the polarization rotation and has the second phase modulation and the second signal light which has no phase modulation to a first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to the phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port of the coupling unit.

The pulse pump light generating unit is used for acquiring the indication information and generating pulse pump light according to the indication information; and sending the generated pulsed pump light to a processing unit; the processing unit is used for performing first phase modulation on the phase of the first signal light through the pulse pump light under the condition of receiving the pulse pump light sent by the pulse pump light generating unit, rotating the polarization of the first signal light subjected to the first phase modulation by 90 degrees to obtain first signal light subjected to the first phase modulation and polarization rotation, performing second phase modulation on the phase of the first signal light subjected to the first phase modulation and polarization rotation through the pulse pump light to obtain first signal light subjected to polarization rotation and second phase modulation, and sending the first signal light subjected to the polarization rotation and second phase modulation to the coupling unit; in the case where the pulsed pump light transmitted by the pulsed pump light generation unit is not received, the first signal light which is not phase-modulated is transmitted to the coupling unit.

In the embodiment of the invention, the signal light is divided into a first signal light and a second signal light; generating pulsed pump light according to the indication information; under the condition that pulse pump light exists, performing first-time phase modulation on the phase of first signal light through the pulse pump light, rotating the polarization of the first signal light subjected to the first-time phase modulation by 90 degrees to obtain first signal light subjected to the first-time phase modulation and polarization rotation, performing second-time phase modulation on the phase of the first signal light subjected to the first-time phase modulation and polarization rotation through the pulse pump light to obtain first signal light subjected to polarization rotation and second-time phase modulation, and sending the first signal light subjected to polarization rotation and second-time phase modulation and second signal light not subjected to phase modulation to a first port; in the case where the pulsed pump light is not present, the first signal light that is not phase-modulated and the second signal light that is not phase-modulated are sent to the second port. After the first signal light is subjected to the first phase modulation through the pulse pump light, the polarization of the first signal light subjected to the first phase modulation is rotated by 90 degrees and then is subjected to the second phase modulation through the pulse pump light, so that the effect that the phase modulation of the first signal light is unrelated to the polarization of the pulse pump light is achieved, and the phase difference between the first signal light and the second signal light is obtained more accurately.

Optionally, in the embodiment of the present invention, the dividing of the signal light into the first signal light and the second signal light specifically means dividing the signal light into the first signal light and the second signal light in terms of power. The coupling unit may be a1 × 2 fiber coupler or other optical device capable of distributing or combining optical signal power among different fibers. Alternatively, only the power of the signal light is distributed by the coupling unit, that is, the power of the first signal light and the power of the second signal light may be the same or different, but other parameters of the first signal light and the second signal light are the same, such as the wavelength, the polarization, the phase, and the like.

Alternatively, the coupling unit 213 may be a coupler capable of realizing two-in and two-out, and may be capable of splitting and combining two optical signals, and combining or interfering the two received optical signals according to the phase difference of the two received optical signals, and then outputting the combined or interfered optical signals from corresponding ports of the coupling unit 213, for example, may be a 3dB optical coupler.

Optionally, the coupling unit further comprises a third port and a fourth port; a coupling unit for: receiving the signal light through a second port, and dividing the signal light into first signal light and second signal light; transmitting the first signal light to the processing unit through the third port; transmitting the second signal light through the fourth port; receiving the first signal light which is subjected to polarization rotation and secondary phase modulation or the first signal light which is not subjected to phase modulation through a third port; receiving the second signal light which is not phase-modulated through the fourth port; under the condition that the first signal light which is transmitted by the processing unit and is subjected to polarization rotation and secondary phase modulation is received through the third port, the first signal light which is received by the third port and is subjected to polarization rotation and secondary phase modulation and the second signal light which is received by the fourth port and is not subjected to phase modulation are transmitted to the first port of the coupling unit; when the first signal light which is not subjected to phase modulation and is transmitted by the processing unit is received through the third port, the first signal light which is not subjected to phase modulation and is received through the third port and the second signal light which is not subjected to phase modulation and is received through the fourth port are transmitted to the second port of the coupling unit.

Optionally, the coupling unit includes four ports, and may receive the signal light through the second port 227 and also receive the signal light through the first port 226, in which only the second port 227 is taken as an example in the embodiment of the present invention. If the first port 226 is used to receive the signal light, the time-domain filter device can play a role of reflection, and the received signal light directly returns from the first port 226 without modulation.

Optionally, the processing unit comprises: the device comprises a multiplexing/demultiplexing unit connected with a pulse pump light generating unit and a coupling unit, a medium unit connected with the multiplexing/demultiplexing unit, and a first Faraday rotator mirror unit connected with the medium unit; the multiplexing/demultiplexing unit is used for coupling the pulse pumping light and the received first signal light sent by the coupling unit under the condition of receiving the pulse pumping light sent by the pulse pumping light generating unit to obtain first coupled signal light; transmitting the first coupled signal light to the medium unit; the fourth coupling signal light is subjected to optical demultiplexing to obtain first signal light which is subjected to polarization rotation and secondary phase modulation, and the first signal light which is subjected to polarization rotation and secondary phase modulation is sent to the coupling unit; the medium unit is used for enabling pulse pump light in the first coupling signal light to perform first-time phase modulation on the phase of the first signal light in the first coupling signal light in the medium unit to obtain first-time phase-modulated first signal light and second coupling signal light coupled by the pulse pump light, and sending the second coupling signal light to the first Faraday rotator mirror unit; the phase of the first signal light which is subjected to the first phase modulation and polarization rotation in the third coupled signal light is subjected to the second phase modulation in the medium unit by the pulse pump light in the third coupled signal light, so that fourth coupled signal light which is subjected to the second phase modulation and polarization rotation is obtained and is coupled with the first signal light and the pulse pump light is sent to the multiplexing/demultiplexing unit; the first Faraday rotator mirror unit is used for rotating the polarization of the first signal light subjected to the first time phase modulation in the second coupled signal light by 90 degrees to obtain first signal light subjected to the first time phase modulation and subjected to the polarization rotation and third coupled signal light optically coupled with the pulse pump; the third coupled signal light is transmitted to the medium unit.

In the embodiment of the present invention, the dielectric unit has various implementation schemes as long as the pulsed pump light can generate a nonlinear effect on the first signal light and the first signal light which is subjected to the first phase modulation and polarization rotation in the dielectric unit, so as to perform the second phase modulation on the phase of the first signal light and the first signal light which is subjected to the first phase modulation and polarization rotation, for example, the dielectric unit may be a Kerr (Kerr) medium, and specifically, may be a medium having third-order nonlinearity, such as a common single-mode fiber, a photonic crystal fiber, a silicon linear waveguide, a quantum dot, and the like.

In the embodiment of the present invention, since the pulsed pump light is some pulses with intervals in time, the multiplexing/demultiplexing unit receives the pulsed pump light in a continuous time period, and does not receive the pulsed pump light in a continuous next time period. That is to say, in the embodiment of the present invention, when the pulsed pump light is received, the first signal light whose polarization is rotated and which is subjected to the second phase modulation and the second signal light which is not subjected to the second phase modulation are output through the first port, and in the embodiment of the present invention, when the pulsed pump light is not received, the first signal light which is subjected to the phase modulation and the second signal light which is not subjected to the phase modulation are output through the second port, so that the first port and the second port of the time domain filtering apparatus in the embodiment of the present invention may be connected to different apparatuses to implement the switching function of the time domain filtering apparatus.

Optionally, the multiplexing/demultiplexing unit is further configured to: under the condition that the pulse pump light sent by the pulse pump light generating unit is not received, the received first signal light sent by the coupling unit is sent to the first Faraday rotator mirror unit through the medium unit; a first faraday rotator mirror unit configured to rotate the polarization of the received first signal light by 90 degrees, to obtain a first signal light without phase modulation; and sending the first signal light which is not subjected to phase modulation to the coupling unit through the medium unit and the multiplexing/demultiplexing unit in sequence.

In the embodiment of the invention, the polarization of the pulse pump light in the second coupling signal light is not rotated by the first Faraday rotator mirror. Optionally, in the embodiment of the present invention, a rotation angle of the magneto-optical crystal in the first faraday rotator mirror unit to the polarization of the first signal light is related to a wavelength of the first signal light, and a specific wavelength of the magneto-optical crystal and the pulse pump light may be selected, so that the whole first faraday rotator mirror unit does not rotate the polarization of the pulse pump light, and only functions as a common mirror, and then the reflected pulse pump light and the first signal light whose polarization is rotated by 90 degrees pass through the dielectric unit, thereby performing a nonlinear interaction, and optionally, the intensity of the nonlinear phase shift is in a linear relationship with the intensity of the pulse pump light.

Further, in order to keep the two paths of signal light reaching the coupling unit in the same polarization state, optionally, the time domain filtering apparatus further includes a second faraday rotating mirror unit connected to the coupling unit; a second Faraday rotator mirror unit to: receiving the second signal light sent by the coupling unit, rotating the polarization of the second signal light by 90 degrees to obtain second signal light without phase modulation, and sending the second signal light without phase modulation to the coupling unit; a coupling unit for: under the condition of receiving the first signal light which is transmitted by the processing unit and has the polarization rotation and the second phase modulation, transmitting the first signal light which has the polarization rotation and has the second phase modulation and the second signal light which has no phase modulation to a first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to the phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port of the coupling unit.

In order to make the light intensities of the two optical signals received by the coupling unit substantially consistent, an attenuation unit is disposed on the optical path of the second optical signal to make the losses of the left and right optical signals identical, and further complete interference occurs at the coupling unit, optionally, the time-domain filtering apparatus further includes: the second Faraday rotation mirror unit is connected with the attenuation unit; an attenuation unit for: receiving the second signal light sent by the coupling unit, performing first attenuation on the second signal light to obtain first attenuated second signal light, and sending the first attenuated second signal light to a second Faraday rotation mirror unit; receiving second signal light which is transmitted by the second Faraday rotation mirror unit and subjected to first attenuation and polarization rotation, performing second attenuation on the second signal light which is subjected to the first attenuation and polarization rotation to obtain second signal light which is not subjected to phase modulation, and transmitting the second signal light which is not subjected to the phase modulation to the coupling unit; a second Faraday rotator mirror unit to: receiving the first-time attenuated second signal light sent by the attenuation unit, rotating the polarization of the first-time attenuated second signal light by 90 degrees to obtain first-time attenuated polarization-rotated second signal light, and sending the first-time attenuated polarization-rotated second signal light to the attenuation unit; a coupling unit for: under the condition of receiving the first signal light which is transmitted by the processing unit and has the polarization rotation and the second phase modulation, transmitting the first signal light which has the polarization rotation and has the second phase modulation and the second signal light which has no phase modulation to a first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to the phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port of the coupling unit.

Optionally, the signal light is a quantum light signal, the first signal light is a first quantum light signal, and the second signal light is a second quantum light signal; the first port is connected with a quantum optical signal receiver; a pulsed pump light generation unit for: receiving a synchronous optical signal; determining indication information according to the synchronous optical signal; wherein the indication information indicates pulse time information of the quantum optical signal; generating pulsed pump light according to the indication information; wherein the pulse time information of the pulsed pump light is matched with the pulse time information of the quantum optical signal.

In a specific implementation, the matching of the pulse time information of the pulsed pump light and the pulse time information of the quantum optical signal specifically means that one pulse of the pulsed pump light corresponds to one pulse of the quantum optical signal, and an overlapping region exists between the time occupied by the corresponding pulse of the pulsed pump light and the time occupied by the pulse of the quantum optical signal, where the overlapping region is greater than an overlapping region threshold. The time length occupied by the overlapping area is the time length of the time domain filter device in the on state when the time domain filter device is used as a switch. In another alternative, the time occupied by the pulse of the corresponding pulsed pump light completely coincides with the time occupied by the pulse of the quantum optical signal, so that the pulse of each quantum optical signal can be obtained more accurately.

In implementation, the quantum signal receiver can recover an original quantum key through pulses of a quantum optical signal, and more noise caused by classical optical signals or other factors exists on other signals, and if the noise enters the quantum signal receiver, the recovery rate of the original quantum key is reduced, and in the prior art, both the pulses of the quantum optical signal and the noise between the pulses of the quantum optical signal enter the quantum signal receiver. A time domain filtering arrangement such as 100ps suppresses noise photons 10 times as much as a quantum detector in a 1ns gate wide quantum signal receiver.

The embodiment of the invention provides a time domain filtering method, which is executed by the device and comprises the following steps:

receiving signal light and dividing the signal light into first signal light and second signal light;

acquiring indication information, and generating pulse pump light according to the indication information; under the condition that pulse pump light exists, performing first-time phase modulation on the phase of first signal light through the pulse pump light, rotating the polarization of the first signal light subjected to the first-time phase modulation by 90 degrees to obtain first signal light subjected to the first-time phase modulation and polarization rotation, performing second-time phase modulation on the phase of the first signal light subjected to the first-time phase modulation and polarization rotation through the pulse pump light to obtain first signal light subjected to polarization rotation and second-time phase modulation, and sending the first signal light subjected to polarization rotation and second-time phase modulation and second signal light not subjected to phase modulation to a first port; in the case where the pulsed pump light is not present, the first signal light that is not phase-modulated and the second signal light that is not phase-modulated are sent to the second port.

Alternatively, receiving the signal light and dividing the signal light into first signal light and second signal light, includes: receiving signal light through a second port; dividing the signal light into first signal light and second signal light; transmitting the first signal light through the third port and transmitting the second signal light through the fourth port; transmitting the first signal light whose polarization is rotated and which is subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation to the first port, including: transmitting the first signal light which is received by the third port and is subjected to polarization rotation and secondary phase modulation and the second signal light which is received by the fourth port and is not subjected to phase modulation to the first port of the coupling unit; transmitting the first signal light without phase modulation and the second signal light without phase modulation to a second port, including: the first signal light received through the third port without phase modulation and the second signal light received through the fourth port without phase modulation are transmitted to the second port of the coupling unit.

Optionally, when there is a pulsed pump light, performing a first phase modulation on a phase of the first signal light by the pulsed pump light, rotating a polarization of the first signal light subjected to the first phase modulation by 90 degrees to obtain a first signal light subjected to the first phase modulation and polarization rotation, and performing a second phase modulation on the phase of the first signal light subjected to the first phase modulation and polarization rotation by the pulsed pump light to obtain a first signal light subjected to the polarization rotation and second phase modulation, includes: under the condition that pulse pump light exists, coupling the pulse pump light and first signal light to obtain first coupled signal light; sending the first coupling signal light to a medium unit, and performing first-time phase modulation on the phase of the first signal light in the first coupling signal light in the medium unit through pulse pump light in the first coupling signal light to obtain first-time phase-modulated first signal light and second coupling signal light coupled by the pulse pump light; rotating the polarization of the first signal light subjected to the first time phase modulation in the second coupling signal light by 90 degrees to obtain a third coupling signal light which is subjected to the first time phase modulation and is optically coupled with the pulse pump light; sending the third coupled signal light to a medium unit, and performing second phase modulation on the phase of the first signal light which is subjected to the first phase modulation and polarization rotation in the third coupled signal light in the medium unit through pulse pump light in the third coupled signal light to obtain fourth coupled signal light which is subjected to the second phase modulation and polarization rotation and is coupled with the pulse pump light; and performing optical demultiplexing on the fourth coupled signal to obtain the first signal light which is subjected to polarization rotation and secondary phase modulation.

Optionally, before sending the first signal light without phase modulation and the second signal light without phase modulation to the second port without pulse pump light, the method further includes: in the absence of the pulsed pump light, the polarization of the first signal light is rotated by 90 degrees, and the first signal light without phase modulation is obtained.

Optionally, the transmitting the first signal light with polarization rotation and second phase modulation and the second signal light without phase modulation to the first port includes: rotating the polarization of the second signal light by 90 degrees to obtain second signal light without phase modulation; transmitting the first signal light which is subjected to polarization rotation and secondary phase modulation and the second signal light which is not subjected to phase modulation to a first port; transmitting the first signal light without phase modulation and the second signal light without phase modulation to a second port, including: rotating the polarization of the second signal light by 90 degrees to obtain second signal light without phase modulation; the first signal light without phase modulation and the second signal light without phase modulation are transmitted to the second port.

Optionally, the transmitting the first signal light with polarization rotation and second phase modulation and the second signal light without phase modulation to the first port includes: performing first attenuation on the second signal light to obtain first attenuated second signal light; rotating the polarization of the second signal light after the first attenuation by 90 degrees to obtain second signal light which is subjected to the first attenuation and polarization rotation; attenuating the second signal light which is subjected to the first attenuation and the polarization rotation to obtain second signal light which is not subjected to phase modulation, and sending the first signal light which is subjected to the polarization rotation and the second phase modulation and the second signal light which is not subjected to the phase modulation to the first port; transmitting the first signal light without phase modulation and the second signal light without phase modulation to a second port, including: performing first attenuation on the second signal light to obtain first attenuated second signal light; rotating the polarization of the second signal light after the first attenuation by 90 degrees to obtain second signal light which is subjected to the first attenuation and polarization rotation; and attenuating the second signal light which is subjected to the first attenuation and polarization rotation to obtain second signal light which is not subjected to phase modulation, and sending the first signal light which is not subjected to phase modulation and the second signal light which is not subjected to phase modulation to a second port.

Optionally, the signal light is a quantum light signal, the first signal light is a first quantum light signal, and the second signal light is a second quantum light signal; the first port is connected with a quantum optical signal receiver; acquiring indication information and generating pulse pump light according to the indication information, comprising: receiving a synchronous optical signal; determining indication information according to the synchronous optical signal; wherein the indication information indicates pulse time information of the quantum optical signal; generating pulsed pump light according to the indication information; wherein the pulse time information of the pulsed pump light is matched with the pulse time information of the quantum optical signal.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings that are required to be used in the description of the embodiments will be briefly described below.

Fig. 1 is a schematic structural diagram of a time-domain filtering optical switch provided in the prior art;

fig. 2 is a schematic structural diagram of a time-domain filtering apparatus according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of another time-domain filtering apparatus according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of another time-domain filtering apparatus according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of another time-domain filtering apparatus according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of another time-domain filtering apparatus according to an embodiment of the present invention;

fig. 7 is a schematic flow chart of signal light output from the coupling unit to the first faraday rotator mirror unit and the second faraday rotator mirror unit in the case of the pulsed pump light in the embodiment of the present invention;

fig. 8 is a schematic flow chart of signal light output from the first faraday rotator mirror unit and the second faraday rotator mirror unit to the coupling unit in the case of the pulsed pump light in the embodiment of the present invention;

fig. 9 is a schematic flow chart of optical path transmission of the first signal light in the case of the pulsed pump light in the embodiment of the present invention;

fig. 10 is a schematic flow chart of signal light output from the coupling unit to the first faraday rotator mirror unit and the second faraday rotator mirror unit without the pulsed pump light in the embodiment of the present invention;

fig. 11 is a schematic flow chart of signal light output from the first faraday rotator mirror unit and the second faraday rotator mirror unit to the coupling unit without the pulsed pump light in the embodiment of the present invention;

fig. 12 is a schematic structural diagram of a quantum communication system using a time-domain filtering apparatus according to an embodiment of the present invention;

fig. 13 is a schematic structural diagram of another quantum communication system using a time-domain filtering apparatus according to an embodiment of the present invention;

fig. 14 is a schematic structural diagram of a communication system applying a time-domain filtering apparatus according to an embodiment of the present invention;

fig. 15 is a schematic diagram of a switching duration when a time-domain filtering apparatus is used as a switch according to an embodiment of the present invention;

fig. 16 is a flowchart illustrating a time-domain filtering method according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Fig. 2 schematically illustrates a structural diagram of a time domain filtering apparatus according to an embodiment of the present invention, as shown in fig. 2, the time domain filtering apparatus 211 includes a coupling unit 213, and a processing unit 212 connected to the coupling unit 213; and a pulsed pump light generation unit 214 connected to the processing unit 212. The coupling unit 213 may include two ports, a first port 226 and a second port 227 in fig. 2.

A coupling unit 213, configured to receive the signal light, divide the signal light into a first signal light and a second signal light, and send the first signal light to the processing unit 212; when receiving the first signal light which is transmitted from the processing unit 212 and is subjected to the second phase modulation, the first signal light which is subjected to the second phase modulation and is subjected to the polarization rotation is transmitted to the first port 226 of the coupling unit 213; in the case of receiving the first signal light without phase modulation transmitted from the processing unit 212, the first signal light without phase modulation and the second signal light without phase modulation are transmitted to the second port 227 of the coupling unit. In an alternative embodiment, the first signal light with polarization rotation and phase modulation performed for the second time and the second signal light without phase modulation interfere in the coupling unit 213, or may also be referred to as being coupled, and then are output from the first port 226 of the coupling unit 213; the first signal light without phase modulation and the second signal light without phase modulation interfere with each other in the coupling unit 213, or may be referred to as being coupled, and then are output from the second port 227 of the coupling unit 213.

Optionally, the coupling unit further comprises a third port 228 and a fourth port 229; a coupling unit for: receiving the signal light through the second port 227 and dividing the signal light into first signal light and second signal light; transmitting the first signal light to the processing unit through the third port 228; transmitting the second signal light through the fourth port 229; receiving the first signal light whose polarization is rotated and which is subjected to the second phase modulation or the first signal light which is not subjected to the phase modulation through the third port 228; the second signal light which is not phase-modulated is received through the fourth port 229; when the first signal light which is transmitted from the processing unit and has been subjected to the second phase modulation by being rotated in polarization is received through the third port 228, the first signal light which is received through the third port 228 and has been subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation and is received through the fourth port 229 are transmitted to the first port 226 of the coupling unit; in the case where the first signal light transmitted by the processing unit without phase modulation is received through the third port 228, the first signal light received through the third port 228 without phase modulation and the second signal light received through the fourth port 229 without phase modulation are transmitted to the second port 227 of the coupling unit.

Alternatively, the second signal light output in the fourth port 229 in the coupling unit may enter the fourth port 229 again. In an alternative embodiment, the second signal light is output from the fourth port 229 and then circularly reenters the fourth port 229, in another alternative embodiment, the second signal light is output from the fourth port 229 and then enters the fourth port 229 again after certain processing, such as polarization rotation, attenuation, and the like, and in any case, the second signal light reentering the fourth port 229 is signal light without phase modulation. The fourth port 229 in fig. 2 is connected to a ring, which is merely an exemplary diagram, and simply describes a process that the second signal light is processed or not processed to be the second signal light without phase modulation, which is described in this application, and then the second signal light without phase modulation is transmitted to the fourth port 229 again.

In this embodiment of the present invention, the coupling unit 213 outputs the two optical signals after interfering with each other from the second port when determining that the phase difference between the two received optical signals is zero. Specifically, when the phase difference between the first signal light without phase modulation and the second signal light without phase modulation received by the coupling unit is zero, the first signal light without phase modulation and the second signal light without phase modulation interfere with each other and are output from the second port 227.

In the embodiment of the present invention, the coupling unit 213 outputs the interfered two optical signals from the first port 226 if the phase difference between the two received optical signals is determined to be not zero and is a preset value. The case a1 can be divided into two cases, in which the two interfered optical signals are all output from the first port, or the case a2 can be divided into two cases, in which the two interfered optical signals are output from the first port and the second port simultaneously.

In case a1, if the preset value is pi, for example, the coupling unit 213 determines that the phase difference between the two optical signals is pi, and the two optical signals are completely output from the first port after being interfered. That is, when the phase difference between the first signal light which is subjected to the first phase modulation and polarization rotation after the phase modulation and received by the coupling means and the second signal light which is not subjected to the phase modulation is pi, the first signal light which is subjected to the first phase modulation and polarization rotation after the phase modulation and the second signal light which is not subjected to the phase modulation are interfered with each other and output from the first port 226. In this embodiment of the present invention, optionally, a phase difference between the first signal light which is subjected to the first phase modulation and is subjected to the polarization rotation after the phase modulation and the second signal light which is not subjected to the phase modulation is pi. That is, in the embodiment of the present invention, the first signal light is subjected to the phase modulation twice, and the total of the modulated phase change amounts of the two phase modulations is pi.

In case a2, alternatively, if there is a phase difference between the first signal light which is phase-modulated and polarization-rotated for the first time and the second signal light which is not phase-modulated, and the phase difference is 0 to pi, the first signal light which is phase-modulated and polarization-rotated for the first time and the second signal light which is not phase-modulated are interfered with each other and then output from the first port 226 and the second port 227, and the ratio of the output from the first port 226 and the second port 227 can be adjusted, for example, according to the phase difference between the first signal light which is phase-modulated and polarization-rotated for the first time and the second signal light which is not phase-modulated.

In the embodiment of the invention, the first signal light of the pulse pump light is subjected to two-time phase modulation successively, and because the light path is short, the attenuation of the pulse pump light in the two-time phase modulation process can be ignored, and the same light intensity of the pulse pump light in the two-time phase modulation process can be considered. Optionally, in the embodiment of the present invention, a phase change amount of the pulsed pump light for performing the first phase modulation on the phase of the first signal light may be adjusted by adjusting the light intensity of the pulsed pump light.

A pulse pump light generating unit 214, configured to acquire the indication information and generate pulse pump light according to the indication information; and transmits the generated pulsed pump light to the processing unit 212.

In the embodiment of the present invention, the pulsed pump light generation unit 214 may obtain the indication information in a variety of ways, such as determined by information sent by the sender, or preset in advance, or preset a rule in advance, and the indication information determined according to the rule, and the like, which is not limited in the embodiment of the present invention. The pulsed pump light in the embodiment of the present invention is the pump light in the form of pulses, that is, the pulsed pump light is pulses with intervals in time, and the specific information of one pulse in the pulsed pump light can be obtained from the indication information, such as the pulse duration, the generation time of the pulsed pump light, the stop time, and the like.

A processing unit 212 configured to, when receiving the pulsed pump light transmitted by the pulsed pump light generation unit 214, perform first phase modulation on the phase of the first signal light by the pulsed pump light, rotate the polarization of the first signal light subjected to the first phase modulation by 90 degrees to obtain first signal light subjected to the first phase modulation and polarization rotation, perform second phase modulation on the phase of the first signal light subjected to the first phase modulation and polarization rotation by the pulsed pump light to obtain first signal light subjected to polarization rotation and second phase modulation, and transmit the first signal light subjected to the polarization rotation and second phase modulation to the coupling unit 213; in the case where the pulsed pump light transmitted by the pulsed pump light generation unit is not received, the first signal light that is not phase-modulated is transmitted to the coupling unit 213.

In the embodiment of the present invention, since the pulsed pump light is a few pulses with intervals in time, the processing unit 212 receives the pulsed pump light in a continuous time period, and does not receive the pulsed pump light in a continuous next time period. That is to say, in the embodiment of the present invention, when the pulsed pump light is received, the first signal light whose polarization is rotated and which is subjected to the second phase modulation and the second signal light which is not subjected to the second phase modulation are output through the first port, and in the embodiment of the present invention, when the pulsed pump light is not received, the first signal light which is subjected to the phase modulation and the second signal light which is not subjected to the phase modulation are output through the second port, so that the first port and the second port of the time domain filtering apparatus in the embodiment of the present invention may be connected to different apparatuses to implement the switching function of the time domain filtering apparatus.

Fig. 3 exemplarily shows a schematic structural diagram of another time-domain filtering apparatus provided in the embodiment of the present invention, as shown in fig. 3, optionally, the processing unit 212 includes: a multiplexing/demultiplexing unit 223 connected to the pulsed pump light generating unit 214 and the coupling unit 213, a dielectric unit 222 connected to the multiplexing/demultiplexing unit 223, and a first faraday rotator mirror unit 221 connected to the dielectric unit 222.

A multiplexing/demultiplexing unit 223, configured to couple the pulse pump light and the received first signal light sent by the coupling unit 213 to obtain a first coupled signal light when receiving the pulse pump light sent by the pulse pump light generating unit 214; transmitting the first coupled signal light to the medium unit 222; the fourth coupling signal light is demultiplexed to obtain the first signal light with the polarization rotated and the second phase modulation performed, and the first signal light with the polarization rotated and the second phase modulation performed is sent to coupling section 213.

A medium unit 222, configured to perform first phase modulation on a phase of first signal light in the first coupled signal light by using pulse pump light in the first coupled signal light in the medium unit 222, obtain first signal light subjected to the first phase modulation and second coupled signal light coupled by using the pulse pump light, and send the second coupled signal light to the first faraday rotator unit 221; and the phase of the first signal light which is subjected to the first phase modulation and polarization rotation in the third coupled signal light is subjected to the second phase modulation in the medium unit by the pulse pump light in the third coupled signal light, so that fourth coupled signal light which is subjected to the second phase modulation and polarization rotation and is coupled by the pulse pump light is obtained, and the fourth coupled signal light is sent to the multiplexing/demultiplexing unit. In the embodiment of the present invention, the dielectric unit has various implementation schemes as long as the pulsed pump light can generate a nonlinear effect on the first signal light and the first signal light which is subjected to the first phase modulation and polarization rotation in the dielectric unit, so as to perform the second phase modulation on the phase of the first signal light and the first signal light which is subjected to the first phase modulation and polarization rotation, for example, the dielectric unit may be a Kerr (Kerr) medium, and specifically, may be a medium having third-order nonlinearity, such as a common single-mode fiber, a photonic crystal fiber, a silicon linear waveguide, a quantum dot, and the like.

Optionally, in the embodiment of the present invention, a phase change amount of the pulsed pump light for performing the first phase modulation on the phase of the first signal light may be adjusted by adjusting the light intensity of the pulsed pump light, and on the other hand, the phase change amount may also be implemented by adjusting parameters such as a material structure of the dielectric unit.

A first faraday rotator unit 221, configured to rotate the polarization of the first signal light subjected to the first phase modulation in the second coupled signal light by 90 degrees, to obtain a third coupled signal light in which the first signal light subjected to the first phase modulation and polarization rotation is optically coupled with the pulse pump; the third coupled signal light is transmitted to the medium unit 222.

The first faraday rotator unit 221 may include therein a faraday rotator, which may be mainly composed of a permanent magnet, a magneto-optical crystal, and a reflector. For example, a 90-degree faraday reflector provides a magnetic field for the magneto-optical crystal through a permanent magnet, when a light beam passes through, the polarization of the light beam can rotate by 45 degrees under the magneto-optical effect, and the light beam can continue to rotate by 45 degrees after being reflected by the reflector and then passes through the magneto-optical crystal again, so that the polarization directions of the incident light and the emergent light finally rotate by 90 degrees.

In the embodiment of the present invention, the second coupling signal light enters the first faraday rotator unit 221, and the first faraday rotator unit rotates only the polarization of the first signal light after the first phase modulation in the second coupling signal light, where the 90-degree polarization rotation in the embodiment of the present invention means that the component in the horizontal direction (X axis) is rotated to the vertical direction (Y axis), and the component in the vertical direction (Y axis) is rotated to the horizontal direction (X axis), such as 90-degree deflection, or 270-degree deflection, and in short, the deflection is rotated by an odd multiple of 90-degree or 90-degree deflection.

For example, the wavelength range of the pulsed pump light and the wavelength range of the first signal light are set to two wavelength ranges that are far apart from each other, and parameters of the first faraday rotator unit are specifically set, so that only the polarization of the first signal light after the first phase modulation in the received second coupled signal light is rotated, and the polarization of the pulsed pump light in the second coupled signal light is not rotated.

Based on this, the multiplexing/demultiplexing unit 223 in the embodiment of the present invention may be a wavelength division multiplexer/demultiplexer, i.e., a coupler related to wavelength. On one hand, the wavelength division multiplexer/demultiplexer can combine optical signals output by a plurality of transmitters with different wavelengths and input the optical signals into an optical fiber; on the other hand, a plurality of optical signals with different wavelengths output by one optical fiber can be separated. Specifically, the multiplexing/demultiplexing unit 223 may couple the received first signal light and the pulse pump light into one optical fiber and output the same to the dielectric unit through the optical fiber, or may separate the pulse pump light and the first signal light that is polarization-rotated and phase-modulated for the second time, which are included in the second interfered signal light output by the dielectric unit, send the first signal light that is polarization-rotated and phase-modulated for the second time to the coupling unit 213 through a port, and output the separated pulse pump light through another port.

Optionally, the multiplexing/demultiplexing unit 223 is further configured to: under the condition that the pulse pump light sent by the pulse pump light generating unit is not received, the received first signal light sent by the coupling unit is sent to the first Faraday rotator mirror unit through the medium unit; a first faraday rotator unit 221 configured to rotate the polarization of the received first signal light by 90 degrees, so as to obtain a first signal light without phase modulation; and sending the first signal light which is not subjected to phase modulation to the coupling unit through the medium unit and the multiplexing/demultiplexing unit in sequence.

That is to say, in the embodiment of the present invention, when the pulsed pump light generation unit 214 does not generate pulsed pump light, the phase of the first signal light split by the coupling unit 213 is not modulated after passing through the multiplexing/demultiplexing unit 223 and the medium unit 222 to the first faraday rotator unit 221 in sequence, so that the phase of the first signal light is not changed, the polarization of the first signal light is deflected by 90 degrees in the first faraday rotator unit 221, and then the polarization is rotated by 90 degrees, and the first signal light without phase modulation passes through the medium unit 222 and the multiplexing/demultiplexing unit 223 in sequence and returns to the coupling unit 213. The coupling unit 213 outputs the first signal light without phase modulation and the second signal light without phase modulation through the second port 227.

In the above, based on the contents shown in fig. 2 and fig. 3, the second optical signal output by the coupling unit 213 is not subjected to phase modulation, and optionally, may be directly returned to the coupling unit 213 without being subjected to other processing procedures, so as to realize the coupling with the first signal light without phase modulation or the first signal light with phase modulation and polarization rotation for the first time, as shown in fig. 2 and fig. 3. Alternatively, in fig. 2 and 3, the polarization of the first signal light whose polarization is rotated and subjected to the second phase modulation may be rotated again by 90 degrees so that the coupling unit 213 realizes coupling between the second signal light which is not subjected to the phase modulation and the first signal light which is not subjected to the phase modulation, or realizes coupling between the second signal light which is not subjected to the phase modulation and the first signal light which is subjected to the first phase modulation and subjected to the polarization rotation.

Further, in order to keep the two signal lights reaching the coupling unit 213 in the same polarization state, a second faraday rotator unit may be correspondingly disposed on the optical path of the second signal light. Fig. 4 schematically shows a structural diagram of another time-domain filtering apparatus provided in an embodiment of the present invention, and as shown in fig. 4, the time-domain filtering apparatus further includes a second faraday rotator 224 connected to the coupling unit 213.

And a second faraday rotator 224 configured to receive the second signal light sent by the coupling unit, rotate the polarization of the second signal light by 90 degrees to obtain a second signal light without phase modulation, and send the second signal light without phase modulation to the coupling unit.

In this embodiment, optionally, the polarization of the second signal light may be rotated by 90 degrees by the second faraday rotator mirror unit 224, and the polarization of the second signal light after the polarization rotation, and the polarization of the second signal light without phase modulation may be the same as the polarization of the first signal light without phase modulation received by the coupling unit 213, and the polarization of the first signal light with phase modulation performed for the first time and polarization rotation may be the same.

The second faraday rotator mirror unit 224 may include therein a faraday rotator mirror, which may be mainly composed of a permanent magnet, a magneto-optical crystal, and a reflector. For example, a 90-degree faraday reflector provides a magnetic field for the magneto-optical crystal through a permanent magnet, when a light beam passes through, the polarization of the light beam can rotate by 45 degrees under the magneto-optical effect, and the light beam can continue to rotate by 45 degrees after being reflected by the reflector and then passes through the magneto-optical crystal again, so that the polarization directions of the incident light and the emergent light finally rotate by 90 degrees.

Accordingly, the coupling unit 213 is configured to, in a case where the first signal light which is transmitted by the processing unit and has the polarization rotated and is subjected to the second phase modulation is received, transmit the first signal light which is transmitted by the processing unit and has the polarization rotated and is subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation to the first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to the phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port of the coupling unit.

In order to make the light intensities of the two optical signals received by the coupling unit 213 substantially consistent, the attenuation unit 225 is disposed on the optical path of the second optical signal, so that the losses of the left and right optical signals are the same, and complete interference occurs at the coupling unit 213. Fig. 5 schematically illustrates a structural diagram of another time-domain filtering apparatus provided in an embodiment of the present invention, and as shown in fig. 5, the time-domain filtering apparatus further includes: an attenuation unit 225 connected to the coupling unit 213, and a second faraday rotator mirror unit 224 connected to the attenuation unit 225.

Optionally, the attenuation unit is configured to receive the second signal light sent by the coupling unit, perform first attenuation on the second signal light to obtain first attenuated second signal light, and send the first attenuated second signal light to the second faraday rotator unit; and receiving the second signal light which is transmitted by the second Faraday rotation mirror unit and subjected to the first attenuation and polarization rotation, attenuating the second signal light which is subjected to the first attenuation and polarization rotation to obtain second signal light which is not subjected to phase modulation, and transmitting the second signal light which is not subjected to phase modulation to the coupling unit. Optionally, the attenuation unit may be an adjustable optical attenuator, and is configured to attenuate optical power of the signal light on the optical path of the second signal light, and the degree of attenuation may be adjusted according to actual needs. After the attenuation unit 225 attenuates the signal on the optical path of the second signal light, the optical powers of the two optical signals received by the coupling unit 213 are substantially the same.

Optionally, the second faraday rotation mirror unit is configured to receive the second signal light after the first attenuation sent by the attenuation unit, rotate the polarization of the second signal light after the first attenuation by 90 degrees to obtain the second signal light after the first attenuation and the polarization rotation, and send the second signal light after the first attenuation and the polarization rotation to the attenuation unit.

Optionally, the coupling unit is configured to, when receiving the first signal light which is transmitted by the processing unit and has a polarization rotated and is subjected to the second phase modulation, transmit the first signal light which is transmitted by the processing unit and has a polarization rotated and is subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation to the first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to the phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port of the coupling unit. In an alternative embodiment, the first signal light whose polarization is rotated and which is subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation interfere in the coupling unit 213, and then are output from the first port 226 of the coupling unit 213; the first signal light without phase modulation and the second signal light without phase modulation interfere with each other in the coupling unit 213, or may be referred to as being coupled, and then are output from the second port 227 of the coupling unit 213.

Fig. 6 schematically shows a structural diagram of another time-domain filtering apparatus provided by the embodiment of the present invention, as shown in fig. 6, an optical circulator 231 is added between the pulsed pump light generation unit 214 and the multiplexing/demultiplexing unit 223, and an optical circulator 232 is connected to the second port 227.

The optical circulator 231 or 232 has a function of allowing light to be transmitted only in a specific direction when light enters from a certain port, and preventing light from being transmitted in other directions, particularly in the reverse direction. Specifically, optical circulator 231 includes port S1, port S2, and port S3. The pulse pump light enters from the port S1 and can only be output from the port S2; when the signal enters from the port S2, the signal can be outputted only from the port S3. Optical circulator 232 includes port S4, port S5, and port S6. The signal light enters from the port S4 and can be outputted only from the port S5; when the signal enters from the port S5, the signal can be outputted only from the port S6.

Fig. 7 schematically shows a flow chart of signal light output from the coupling unit to the first faraday rotator mirror unit and the second faraday rotator mirror unit in the case of the pulsed pump light in the embodiment of the present invention, fig. 8 schematically shows a flow chart of signal light output from the first faraday rotator mirror unit and the second faraday rotator mirror unit to the coupling unit in the case of the pulsed pump light in the embodiment of the present invention, and fig. 9 schematically shows a flow chart of optical path transmission of the first signal light in the case of the pulsed pump light in the embodiment of the present invention. An example provided by an embodiment of the present invention is described below with reference to fig. 7, 8, and 9.

As shown in fig. 7, the coupling unit 213 splits the signal light into first signal light and second signal light, transmits the first signal light to the multiplexing/demultiplexing unit 223, and transmits the second signal light to the attenuation unit 225.

Case b1, in the case of the pulsed pump light, the optical path transmission process corresponding to the second signal light:

and an attenuation unit 225, configured to receive the second signal light sent by the coupling unit, perform first attenuation on the second signal light to obtain first attenuated second signal light, and send the first attenuated second signal light to the second faraday rotator unit 224. The second faraday rotator 224 rotates the polarization of the first attenuated second signal light by 90 degrees to obtain the first attenuated and polarization-rotated second signal light, and transmits the first attenuated and polarization-rotated second signal light to the attenuation unit. As shown in fig. 8, the attenuation unit 225 attenuates the second signal light that is subjected to the first attenuation and polarization rotation to obtain second signal light that is not subjected to phase modulation, and transmits the second signal light that is not subjected to phase modulation to the coupling unit.

Case b2, in the case of the pulsed pump light, the optical path transmission process corresponding to the first signal light:

the pulsed pump light generation unit 214 transmits the generated pulsed pump light to the multiplexing/demultiplexing unit 223.

A multiplexing/demultiplexing unit 223, which couples the pulsed pump light and the first signal light to obtain a first coupled signal light when receiving the pulsed pump light sent by the pulsed pump light generating unit; the first coupled signal light is transmitted to the medium unit 222.

The dielectric unit 222 is configured to perform first phase modulation on the phase of the first signal light in the first coupled signal light by using the pulse pump light in the first coupled signal light, obtain first signal light subjected to the first phase modulation and second coupled signal light coupled by using the pulse pump light, and send the second coupled signal light to the first faraday rotator unit 221.

And a first faraday rotator unit 221 configured to rotate the polarization of the first signal light subjected to the first phase modulation in the second coupled signal light by 90 degrees, to obtain a third coupled signal light in which the first signal light subjected to the first phase modulation and polarization rotation is optically coupled to the pulsed pump light. As shown in fig. 8, the third coupled signal light is transmitted to the medium unit 222.

The medium unit 222 is configured to perform, in the third coupled signal light, second phase modulation on a phase of a first signal light, which is subjected to first phase modulation and polarization rotation, in the third coupled signal light in the medium unit by using a pulse pump light in the third coupled signal light, generate a nonlinear effect on the first signal light, which is subjected to first phase modulation and polarization rotation, in the medium unit by using the pulse pump light, obtain a fourth coupled signal light, which is coupled by the first signal light and the pulse pump light, and transmit the fourth coupled signal light to the multiplexing/demultiplexing unit 223;

multiplexing/demultiplexing section 223 demultiplexes the fourth coupling signal light to obtain the first signal light whose polarization is rotated and which is subjected to the second phase modulation, and transmits the first signal light whose polarization is rotated and which is subjected to the second phase modulation to coupling section 213. The demultiplexed pulsed pump light is emitted from another port, such as in fig. 6, and the demultiplexed pulsed pump light is emitted from port S3 of the optical circulator 231.

When receiving the first signal light that is subjected to the second phase modulation with the polarization rotated and transmitted from the processing unit, coupling unit 213 transmits the first signal light that is subjected to the second phase modulation with the polarization rotated and the second signal light that is not subjected to the phase modulation to first port 226 of the coupling unit.

As shown in fig. 9, the multiplexing/demultiplexing unit 223 receives the first signal light, the component of the first signal light on the X axis is Xa, the component of the first signal light on the Y axis is Ya, and the absolute value of Ya may be greater than, equal to, or less than the absolute value of Xa. The multiplexing/demultiplexing unit 223 receives the pulsed pump light, a component of the pulsed pump light in the X axis is Xb, a component of the pulsed pump light in the Y axis is Yb, and an absolute value of Yb may be greater than, equal to, or less than an absolute value of Xb. The multiplexing/demultiplexing unit 223 multiplexes the first signal light and the pulsed pump light and inputs the multiplexed light to the value medium unit 222. Ya is modulated by Yb and Xa is modulated by Xb. And then into the first faraday rotator mirror unit 221. In first faraday rotator 221, the polarization of Xa subjected to the modulation by Xb is rotated by 90 degrees to become a component on the Y axis, and the polarization of Ya subjected to the modulation by Yb is rotated by 90 degrees to become a component on the X axis. The polarization of the pulsed pump light is not deflected, so the component in the X-axis is still Xb, and the component in the Y-axis is still Yb. The polarization is rotated and enters the medium unit 222, Xa subjected to the modulation action of Xb is a component on the Y axis, subjected to the nonlinear modulation action of a Y axis component Yb of the pulsed pump light, Ya subjected to the modulation action of Yb is a component on the X axis, subjected to the nonlinear modulation action of an X axis component Xb of the pulsed pump light, and then received into the multiplexing/demultiplexing unit 223 to be demultiplexed and output. The Y-axis component of the obtained first signal light whose polarization is rotated and which is subjected to the second phase modulation is Xa sequentially subjected to Xb and Yb modulation, and the X-axis component of the obtained first signal light whose polarization is rotated and which is subjected to the second phase modulation is Ya sequentially subjected to Yb and Xb modulation. That is to say, the X-axis and Y-axis components of the first signal light are both modulated by Xb and Yb, so that the X-axis and Y-axis components of the first signal light are guaranteed to have the same phase modulation variation, and the phase modulation variation of the first signal light is guaranteed not to be affected by the polarization of the first signal light and/or the polarization of the pulsed pump light.

That is to say, no matter what kind of polarization the incident pulsed pump light and the first signal light are, the nonlinear phase shift that the forward direction incident of the first signal light and the reflected light that passes through the first faraday rotator unit are a complementary process, and the purpose of outputting the first signal light and the second signal light that is not phase-modulated from the first port can be achieved only by ensuring that the sum of the nonlinear phase shifts that the first signal light undergoes in the forward direction and the reflected light is a preset value, for example, pi.

Fig. 10 schematically shows a flow chart of signal light output from the coupling unit to the first faraday rotator mirror unit and the second faraday rotator mirror unit without the pulsed pump light in the embodiment of the present invention, and fig. 11 schematically shows a flow chart of signal light output from the first faraday rotator mirror unit and the second faraday rotator mirror unit to the coupling unit without the pulsed pump light in the embodiment of the present invention. An example provided by an embodiment of the present invention is described below with reference to fig. 10 and 11.

As shown in fig. 10, the coupling unit 213 splits the signal light into first signal light and second signal light, transmits the first signal light to the multiplexing/demultiplexing unit 223, and transmits the second signal light to the attenuation unit 225.

In case c1, in the case of no pulsed pump light, the optical path transmission process corresponding to the second signal light is the same as that in case b1, and is not described herein again.

In case c2, in the absence of the pulsed pump light, the optical path transmission process corresponding to the first signal light is as follows:

the multiplexing/demultiplexing unit 223 transmits the received first signal light to the first faraday rotator unit 221 through the medium unit 222 without receiving the pulsed pump light transmitted from the pulsed pump light generating unit. Since there is no pulsed pump light, the phase of the first signal light is not modulated by the pulsed pump light in this case.

A first faraday rotator unit 221 configured to rotate the polarization of the first signal light by 90 degrees to obtain the first signal light without phase modulation; the first signal light which is not phase-modulated is transmitted to the coupling unit 213 through the medium unit 222 and the multiplexing/demultiplexing unit 223 in order.

When receiving the first signal light that is not phase-modulated, the coupling unit 213 transmits the first signal light that is not phase-modulated and the second signal light that is not phase-modulated to the second port 227 of the coupling unit. Alternatively, as shown in fig. 6, the coupling unit 213 transmits the first signal light without phase modulation and the second signal light without phase modulation to the port S5 of the optical circulator 232 through the second port 227, and outputs the signals from the port S6.

The time-domain filtering device 211 provided in the embodiment of the present invention may be applied to various scenarios, for example, a transmission scenario of a quantum optical signal, fig. 12 schematically illustrates a structure diagram of a quantum communication system using the time-domain filtering device provided in the embodiment of the present invention, and fig. 13 schematically illustrates a structure diagram of another quantum communication system using the time-domain filtering device provided in the embodiment of the present invention.

In a specific implementation, the matching of the pulse time information of the pulsed pump light and the pulse time information of the quantum optical signal specifically means that one pulse of the pulsed pump light corresponds to one pulse of the quantum optical signal, and an overlapping region exists between the time occupied by the corresponding pulse of the pulsed pump light and the time occupied by the pulse of the quantum optical signal, where the overlapping region is greater than an overlapping region threshold. The time length occupied by the overlapping area is the time length of the time domain filter device in the on state when the time domain filter device is used as a switch. In another alternative, the time occupied by the pulse of the corresponding pulsed pump light completely coincides with the time occupied by the pulse of the quantum optical signal, so that the pulse of each quantum optical signal can be obtained more accurately. This is explained below by way of a detailed example.

As shown in fig. 12, in the embodiment of the present invention, the transmitting end includes a classical signal transmitter 201, a synchronous signal transmitter 202, and a quantum signal transmitter 203, and the classical optical signal sent by the classical signal transmitter 201, the synchronous optical signal sent by the synchronous signal transmitter 202, and the quantum optical signal sent by the quantum signal transmitter 203 are sent to the receiving end through a wavelength division multiplexing unit 204. Other multiplexing modes can also be used, and the embodiment of the present invention is described by taking wavelength division multiplexing as an example.

The receiving end recovers the received signal into a classical optical signal, a synchronous optical signal and a quantum optical signal through the wavelength division demultiplexing unit 205, or through other multiplexing methods. The classical optical signal is sent to classical signal receiver 206 and the synchronization optical signal is optionally split by optical splitter 209 into a first synchronization optical signal and a second synchronization optical signal, optionally optical splitter 209 only splits the power of the synchronization optical signal, i.e. the power of the first synchronization optical signal and the power of the second synchronization optical signal are the same or different, and other parameters of the first synchronization optical signal and the second synchronization optical signal, such as wavelength etc., are the same. The optical splitter 209 may be a1 x 2 fiber coupler or other optical device capable of distributing or combining optical signal power between different fibers. Alternatively, only the power of the synchronization optical signal is distributed by the optical splitter, i.e. the power of the first synchronization optical signal and the power of the second synchronization optical signal may be the same or different, but other parameters of the first synchronization optical signal and the second synchronization optical signal are the same, such as the wavelength, the polarization, the phase, and the like. The quantum optical signal becomes signal light, is input to port S4 of optical circulator 232, and enters coupling section 213 through port S5.

The second synchronization optical signal enters the pulsed pump light generation unit 214 for generating a pulsed pump light signal. The synchronous optical signal records pulse information of the quantum optical signal, that is, the quantum optical signal is also a pulse, and the pulse information of the quantum optical signal can be determined by the second synchronous optical signal separated from the synchronous optical signal, for example, at what time point the pulse information reaches a receiving end, and the like. An alternative implementation is to generate new intense light as pulsed pump light based on the indication information, and another implementation is to subject the second synchronization optical signal to processing, such as amplification by an amplifier, to obtain pulsed pump light.

Optionally, the first port 226 of the coupling unit 213 is connected to the quantum signal receiver 208. That is, in the embodiment of the present invention, in the case that the quantum optical signal pulse is not received, the pulsed pump light is not generated, so that the quantum optical signal sent by the quantum signal transmitter is output through the second port, for example, output through the port S6, and the optical signal in this portion is discarded. Only when the pulse of the quantum optical signal is received, the pulse of the pulse pump light is correspondingly generated, so that the quantum optical signal pulse is input to the quantum signal receiver 208 through the second port, and as can be seen, the time domain filtering device realizes the on-off function under the condition of generating the pulse pump light, the pulse of the quantum optical signal is successfully input to the quantum signal receiver, and realizes the off-on function under the condition of not generating the pulse pump light, and the received optical signal is not input to the quantum signal receiver.

In implementation, the quantum signal receiver can recover an original quantum key through pulses of a quantum optical signal, and more noise caused by classical optical signals or other factors exists on other signals, and if the noise enters the quantum signal receiver, the recovery rate of the original quantum key is reduced, and in the prior art, both the pulses of the quantum optical signal and the noise between the pulses of the quantum optical signal enter the quantum signal receiver. For example, a 100 picosecond (ps) time domain filtering device has 10 times the ability to reject noise photons as compared to a quantum detector in a1 nanosecond (ns) gate width quantum signal receiver.

Alternatively, since only quantum signals need to be received in the mixed transmission system, the optical circulator in the scheme can be replaced by an isolator or omitted, which reduces the loss of the quantum signals by the system.

As shown in fig. 13, in the embodiment of the present invention, the quantum optical signal may be obtained by performing a multiplexing process on multiple sub-quantum optical signals, such as a sub-quantum optical signal 241, a sub-quantum optical signal 242, and the like at the transmitting end through a multiplexer 246. At the receiving end, the first port of the coupling unit 213 may be connected to a splitter 245, and the received quantum optical signal pulse may be split into a plurality of sub-quantum optical signals, such as the sub-quantum optical signal 243 and the sub-quantum optical signal 244, so as to be detected respectively.

In addition to the above description, the time domain filtering device in the embodiment of the present invention may also be applied to the aspects of FDDI, optical node bypass, loop test sensing system, etc., and may also be used in combination with other types of optical switches, so that a switching system formed by the time domain filtering device is more complete and flexible. Fig. 14 exemplarily shows a schematic structural diagram of a communication system applying a time domain filtering apparatus according to an embodiment of the present invention, as shown in fig. 14, the communication system includes two time domain filtering apparatuses, a time domain filtering apparatus 211 at a transmitting end and a time domain filtering apparatus 271 at a receiving end, where the time domain filtering apparatus 211 may also be applied at the receiving end, and this embodiment of the present invention is merely an example.

In case d1, the signal light is transmitted from the transmission device 261 to the transmission device 262.

When no pump pulse is input, the signal light is input from the port S4, output through the port S5 of the optical circulator 232, then enter the time domain filter device 211, return to the original path, output from the second port 227, enter the optical circulator 232 again, output from the port S6 of the optical circulator 232, transmitted from the main path to the port S15 of the optical circulator 293, and enter the transmission device 262 through the port S14 thereof.

When the main path has service or has a fault, the signal light can be transmitted from the standby path. Specifically, the signal light passes through the 1:2 coupler at the end of the transmission device 261, and is divided into two parts, wherein one part of the signal light is transmitted to the transmission device 262, and the other part of the signal light is used as a trigger signal of the pump pulse, so that the time-domain filtering device 211 produces the pulse pump light.

When a pump pulse is input, signal light is input from the port S4, output through the port S5 of the optical circulator 232, then input into the time-domain filter device 211, output from the first port 226, input through the port S7 of the optical circulator 251, output from the port S8, output to the port S10 of the optical circulator 292 through a backup circuit, and output to the transmission device 262 through the port S12.

In case d2, the signal light is transmitted from the transmission device 262 to the transmission device 261.

When no pump pulse is input, the signal light is input from the port S14 of the optical circulator 293, enters the time domain filter device 271 through the port S13 of the optical circulator 293, enters the second port 287, returns to the original path, is output from the second port 287, enters the optical circulator 293 again, is output from the port S15 of the optical circulator 293, is transmitted to the port S6 of the optical circulator 232 from the main path, and enters the transmission device 261 through the port S4 thereof.

Specifically, the signal light passes through the 1:2 coupler at the end of the transmission device 262, and is divided into two parts, wherein one part of the signal light is transmitted to the transmission device 261, and the other part of the signal light is used as a trigger signal of the pump pulse, so that the time-domain filtering device 271 produces the pulse pump light.

When a pump pulse is input, signal light is input from the port S14 of the optical circulator 293, output through the port S13 of the optical circulator 293, enter the time domain filtering device 271, output from the first port 286 to the port S11 of the optical circulator 292, output from the port S10, output to the port S8 of the optical circulator 251 through a backup circuit, and output to the transmission device 261 through the port S9.

Based on the time domain filtering devices shown in fig. 2 to 14, fig. 15 exemplarily shows a schematic diagram of the on-time duration of the light when the time domain filtering device provided by the embodiment of the present invention is used as a switch, as shown in fig. 15, since the time domain filtering device is independent of the polarization, it can be assumed that the polarization of the pulsed pump light is the same as that of the signal light, and the following analysis is also true when the polarizations are different. The dielectric units in fig. 2 to 4 may be configured as Kerr dielectric, such as a common single-mode fiber with third-order nonlinearity, and assuming that the speed of the pulsed pump light is slower than that of the signal light, the optical path of the light beam back and forth is L, that is, the stroke of the first signal light from the multiplexing/demultiplexing unit to the multiplexing/demultiplexing unit is L, and the pulse width of the pulsed pump light is t_p. The pulse of the pulsed pump light and the pulse of the first signal light multiplex/demultiplex unit at the same time, but since the pulse of the first signal light has a fast speed, after the pulse of the first signal light reaches the end point, the trailing edge of the pulse of the pulsed pump light and the t of the pulse of the first signal light are the same_pThe position of + t is aligned, where t is a time by which the pulse of the first signal light leads the pulse of the pulsed pump light, and can be expressed by the following formula (1):

in formula (1), L is a stroke of the first signal light from the multiplexing/demultiplexing unit to the multiplexing/demultiplexing unit; t is the pulse lead time of the pulse of the first signal light than the pulse of the pulse pump light; v_pIs the speed of the pulsed pump light; v_sIs the speed of the first signal light.

As can be seen from fig. 15, the entire pulse width t of the pulse of the first signal light_sInner, only t_pThe first signal light in + t time will interact with the pulsed pump light, and this interaction will introduce a predetermined phase difference, e.g. a non-linear phase shift of pi, to follow the dead timeThe line phase modulated second signal light is interfered and then comes out from the first port. The other part of the pulse of the first signal light is not nonlinearly phase-shifted from the pulse pump light, and thus interferes with the second signal light which is not phase-modulated, and then comes out of the second port. Thus, finally, the switching time duration for the entire time-domain filter arrangement as a switch is t_p+t。

Therefore, in the embodiment of the invention, the on-off duration of the time domain filtering device can be regulated and controlled by adjusting the pulse width and the fiber length of the pulse pump light and selecting different wavelengths of the first signal light and the pulse pump light. For example, when the pump light is 1550 nanometers (nm), the pulse width is 50ps, and the first signal light is 1310nm, the first signal light isPicoseconds per meter (ps/m), when the optical length L is 25m, a switching time of 100ps can be generated for the signal light.

Similarly, if the propagation speed of the pulsed pump light is faster than that of the first signal light, the switching time of the entire time-domain filter device is t_s+ t' can be expressed by the following formula (2):

in formula (2), L is a stroke of the first signal light from the multiplexing/demultiplexing unit to the multiplexing/demultiplexing unit; t' is the leading time of the pulse pump light compared with the first signal light; v_pIs the speed of the pulsed pump light; v_sIs the speed of the first signal light.

In the embodiment of the present invention, optionally, in order to reduce the length L of the optical fiber and make the system more stable, a larger speed difference between the pulsed pump light and the first signal light is required, which means that the pulsed pump light wavelength is required to be separated from the first signal light wavelength by a large distance, and this can reduce the interference of the pulsed pump light on the first signal light, so that the influence of noise photons generated by the pulsed pump light on the first signal light is minimized. In addition, optionally, the structure of the dielectric unit can be designed according to requirements to realize specific functions, such as increasing the third-order nonlinearity of the structure, increasing or decreasing the speed difference between the pump light and the signal light, reducing the nonlinear noise of the system, and the like.

It can be seen from the above that, in the embodiment of the present invention, the equiarm michelson interferometer equipped with the faraday rotator and the nonlinear phase shift generated by the cross-phase modulation of the pulse pump light on the first signal light are used to implement the extremely narrow time-domain filtering device unrelated to the polarization of both the pulse pump light and the first signal light, and the device is a low-cost and low-loss device. Meanwhile, time domain filtering is carried out on the quantum signal and classical signal same-fiber mixed transmission system based on the device, the gate width of the single-photon detector is equivalently shortened, the influence of noise photons on the system is reduced, and the mixed transmission performance of the system is improved.

Fig. 16 illustrates a flow diagram of a temporal filtering method.

Based on the same concept, an embodiment of the present invention provides a schematic flow diagram of a time-domain filtering method, as shown in fig. 16, the time-domain filtering method includes:

step 1601, receiving signal light, and dividing the signal light into a first signal light and a second signal light;

step 1602, acquiring indication information, and generating a pulse pump light according to the indication information; in the case of pulsed pump light, step 1603 is performed; in the absence of pulsed pump light, performing step 1604;

step 1603, performing first phase modulation on the phase of the first signal light through the pulse pump light, rotating the polarization of the first signal light subjected to the first phase modulation by 90 degrees to obtain first signal light subjected to the first phase modulation and polarization rotation, performing second phase modulation on the phase of the first signal light subjected to the first phase modulation and polarization rotation through the pulse pump light to obtain first signal light subjected to polarization rotation and second phase modulation, and sending the first signal light subjected to polarization rotation and second phase modulation and second signal light not subjected to phase modulation to the first port;

in step 1604, the first signal light without phase modulation and the second signal light without phase modulation are transmitted to a second port.

In an optional scheme, the received signal light is received through the second port of the coupling unit in the above embodiment, and the signal light is divided into the first signal light and the second signal light, and then the first signal light whose polarization is rotated and which is subjected to the second phase modulation and the second signal light which is not subjected to the phase modulation are sent to the first port of the coupling unit, and the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation are sent to the second port of the coupling unit.

It should be apparent to those skilled in the art that embodiments of the present invention may be provided as a method, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. The time domain filtering device is characterized by comprising a coupling unit and a processing unit connected with the coupling unit; a pulsed pump light generation unit connected to the processing unit; the coupling unit comprises a first port and a second port; wherein:

the coupling unit is used for receiving signal light, dividing the signal light into first signal light and second signal light, and sending the first signal light to the processing unit; under the condition of receiving the first signal light which is transmitted by the processing unit and has the polarization rotation and the second phase modulation, transmitting the first signal light which has the polarization rotation and the second phase modulation and the second signal light which has no phase modulation to the first port of the coupling unit; under the condition that the first signal light which is not subjected to phase modulation and is sent by the processing unit is received, the first signal light which is not subjected to phase modulation and the second signal light which is not subjected to phase modulation are sent to the second port of the coupling unit;

the pulse pump light generating unit is used for acquiring indication information and generating pulse pump light according to the indication information; and transmitting the generated pulsed pump light to the processing unit;

the processing unit is configured to, when receiving the pulsed pump light transmitted by the pulsed pump light generation unit, perform first phase modulation on a phase of first signal light by the pulsed pump light, rotate the polarization of the first signal light subjected to the first phase modulation by 90 degrees to obtain first signal light subjected to the first phase modulation and polarization rotation, perform second phase modulation on the phase of the first signal light subjected to the first phase modulation and polarization rotation by the pulsed pump light to obtain first signal light subjected to the polarization rotation and second phase modulation, and transmit the first signal light subjected to the polarization rotation and second phase modulation to the coupling unit; and transmitting the first signal light without phase modulation to the coupling unit without receiving the pulsed pump light transmitted by the pulsed pump light generation unit.

2. The time-domain filtering device of claim 1, wherein the coupling unit further comprises a third port and a fourth port; the coupling unit is configured to:

receiving signal light through the second port, and dividing the signal light into first signal light and second signal light;

transmitting the first signal light to the processing unit through the third port;

transmitting the second signal light through the fourth port;

receiving the first signal light which is subjected to the polarization rotation and the second phase modulation or the first signal light which is not subjected to the phase modulation through the third port;

receiving the second signal light without phase modulation through the fourth port;

when first signal light which is transmitted by the processing unit and is subjected to polarization rotation and secondary phase modulation is received through the third port, transmitting the first signal light which is received by the third port and is subjected to polarization rotation and secondary phase modulation and second signal light which is received by the fourth port and is not subjected to phase modulation to the first port of the coupling unit;

and when the first signal light which is not subjected to phase modulation and is sent by the processing unit is received through the third port, sending the first signal light which is not subjected to phase modulation and is received through the third port and the second signal light which is not subjected to phase modulation and is received through the fourth port to the second port of the coupling unit.

3. The temporal filtering device according to claim 1 or 2, wherein the processing unit comprises: the multiplexing/demultiplexing unit is connected with the pulse pump light generating unit and the coupling unit, the medium unit is connected with the multiplexing/demultiplexing unit, and the first Faraday rotation mirror unit is connected with the medium unit;

the multiplexing/demultiplexing unit is configured to couple the pulse pump light and the received first signal light sent by the coupling unit to obtain a first coupled signal light when the pulse pump light sent by the pulse pump light generating unit is received; transmitting the first coupled signal light to the media unit; demultiplexing the fourth coupling signal light to obtain the first signal light with the polarization rotated and the second time phase modulation, and sending the first signal light with the polarization rotated and the second time phase modulation to the coupling unit;

the medium unit is configured to perform, in the first coupled signal light, first phase modulation on a phase of the first signal light in the first coupled signal light in the medium unit to obtain first signal light subjected to the first phase modulation and second coupled signal light coupled by the pulse pump light, and send the second coupled signal light to the first faraday rotator unit; enabling the pulse pump light in the third coupled signal light to perform second phase modulation on the phase of the first signal light which is subjected to the first phase modulation and polarization rotation in the third coupled signal light in the medium unit to obtain first signal light which is subjected to the second phase modulation and polarization rotation and fourth coupled signal light which is coupled by the pulse pump light, and sending the fourth coupled signal light to the multiplexing/demultiplexing unit;

the first faraday rotator unit is configured to rotate the polarization of the first signal light subjected to the first time phase modulation in the second coupled signal light by 90 degrees, so as to obtain the first signal light subjected to the first time phase modulation and subjected to the polarization rotation and a third coupled signal light optically coupled with the pulse pump; transmitting the third coupled signal light to the media unit.

4. The time-domain filtering apparatus of claim 3, wherein the multiplexing/demultiplexing unit is further configured to:

under the condition that the pulse pump light sent by the pulse pump light generating unit is not received, the received first signal light sent by the coupling unit is sent to the first Faraday rotation mirror unit through the medium unit;

the first Faraday rotator mirror unit is configured to:

rotating the polarization of the received first signal light by 90 degrees to obtain the first signal light without phase modulation; and sending the first signal light without phase modulation to the coupling unit sequentially through the medium unit and the multiplexing/demultiplexing unit.

5. A time domain filter arrangement according to any one of claims 1, 2 or 4, further comprising a second Faraday rotator mirror element coupled to the coupling element;

the second Faraday rotator mirror unit is configured to:

receiving second signal light sent by the coupling unit, rotating the polarization of the second signal light by 90 degrees to obtain the second signal light without phase modulation, and sending the second signal light without phase modulation to the coupling unit;

the coupling unit is configured to:

under the condition of receiving the first signal light which is transmitted by the processing unit and has the polarization rotation and the second phase modulation, transmitting the first signal light which has the polarization rotation and has the second phase modulation and the second signal light which has no phase modulation to a first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to phase modulation and the second signal light which is not subjected to phase modulation to a second port of the coupling unit.

6. The temporal filtering device according to any of claims 1, 2 or 4, wherein the temporal filtering device further comprises: the second Faraday rotation mirror unit is connected with the attenuation unit;

the attenuation unit is used for:

receiving second signal light sent by the coupling unit, performing first attenuation on the second signal light to obtain first attenuated second signal light, and sending the first attenuated second signal light to the second Faraday rotator unit; receiving second signal light which is transmitted by the second Faraday rotation mirror unit and subjected to first attenuation and polarization rotation, performing second attenuation on the second signal light which is subjected to the first attenuation and polarization rotation to obtain second signal light which is not subjected to phase modulation, and transmitting the second signal light which is not subjected to phase modulation to the coupling unit;

the second Faraday rotator mirror unit is configured to:

receiving the first-time attenuated second signal light sent by the attenuation unit, rotating the polarization of the first-time attenuated second signal light by 90 degrees to obtain first-time attenuated polarization-rotated second signal light, and sending the first-time attenuated polarization-rotated second signal light to the attenuation unit;

the coupling unit is configured to:

under the condition that the first signal light which is transmitted by the processing unit and is subjected to polarization rotation and secondary phase modulation is received, transmitting the first signal light which is subjected to polarization rotation and secondary phase modulation and the second signal light which is not subjected to phase modulation to a first port of the coupling unit; and under the condition of receiving the first signal light which is not subjected to phase modulation and is sent by the processing unit, sending the first signal light which is not subjected to phase modulation and the second signal light which is not subjected to phase modulation to a second port of the coupling unit.

7. The time-domain filtering device of any one of claims 1, 2, or 4, wherein the signal light is a quantum optical signal, the first signal light is a first quantum optical signal, and the second signal light is a second quantum optical signal; the first port is connected with a quantum optical signal receiver;

the pulsed pump light generation unit is configured to:

receiving a synchronous optical signal;

determining the indication information according to the synchronous optical signal; wherein the indication information indicates pulse time information of the quantum light signal;

generating the pulse pumping light according to the indication information; wherein the pulse time information of the pulsed pump light matches the pulse time information of the quantum optical signal.

8. A method of time-domain filtering, comprising:

acquiring indication information, and generating pulse pump light according to the indication information;

under the condition that the pulse pump light exists, performing first-time phase modulation on the phase of first signal light through the pulse pump light, rotating the polarization of the first signal light subjected to the first-time phase modulation by 90 degrees to obtain the first signal light subjected to the first-time phase modulation and polarization rotation, performing second-time phase modulation on the phase of the first signal light subjected to the first-time phase modulation and polarization rotation through the pulse pump light to obtain the first signal light subjected to the polarization rotation and the second-time phase modulation, and sending the first signal light subjected to the polarization rotation and the second-time phase modulation and the second signal light not subjected to the phase modulation to a first port;

transmitting the first signal light without phase modulation and the second signal light without phase modulation to a second port without the pulsed pump light.

9. The time-domain filtering method of claim 8, wherein the receiving the signal light and splitting the signal light into a first signal light and a second signal light comprises:

receiving signal light through the second port;

dividing the signal light into the first signal light and the second signal light;

transmitting the first signal light through a third port and transmitting the second signal light through a fourth port;

the transmitting the first signal light which is subjected to the polarization rotation and the second phase modulation and the second signal light which is not subjected to the phase modulation to a first port includes:

transmitting the first signal light which is received through the third port and is subjected to polarization rotation and secondary phase modulation and the second signal light which is received through the fourth port and is not subjected to phase modulation to the first port of the coupling unit;

the transmitting the first signal light without phase modulation and the second signal light without phase modulation to a second port includes:

and sending the first signal light which is received through the third port and is not subjected to phase modulation and the second signal light which is received through the fourth port and is not subjected to phase modulation to the second port of the coupling unit.

10. The time-domain filtering method according to claim 8 or 9, wherein the obtaining the first signal light with the first phase modulation and the polarization rotation by performing the first phase modulation on the phase of the first signal light by the pulsed pump light and rotating the polarization of the first signal light with the first phase modulation by 90 degrees in the presence of the pulsed pump light, and the obtaining the first signal light with the polarization rotation and the second phase modulation by performing the second phase modulation on the phase of the first signal light with the first phase modulation and the polarization rotation by the pulsed pump light comprises:

under the condition that the pulse pumping light exists, coupling the pulse pumping light and the first signal light to obtain first coupled signal light;

transmitting the first coupling signal light to a medium unit, and performing first-time phase modulation on the phase of first signal light in the first coupling signal light in the medium unit through the pulse pump light in the first coupling signal light to obtain first-time phase-modulated first signal light and second coupling signal light coupled by the pulse pump light;

rotating the polarization of the first signal light subjected to the first time phase modulation in the second coupling signal light by 90 degrees to obtain a third coupling signal light which is coupled by the first signal light subjected to the first time phase modulation and polarization rotation and the pulse pump light;

transmitting the third coupled signal light to the medium unit, and performing second phase modulation on the phase of the first signal light which is subjected to the first phase modulation and polarization rotation in the third coupled signal light in the medium unit through the pulse pump light in the third coupled signal light to obtain the first signal light which is subjected to the second phase modulation and polarization rotation and the fourth coupled signal light which is coupled with the pulse pump light;

and performing optical demultiplexing on the fourth coupled signal light to obtain the first signal light which is subjected to polarization rotation and secondary phase modulation.

11. The time-domain filtering method of claim 10, wherein before sending the first signal light without phase modulation and the second signal light without phase modulation to a second port without the pulsed pump light, further comprising:

and under the condition of no pulse pump light, rotating the polarization of the first signal light by 90 degrees to obtain the first signal light without phase modulation.

12. A method of time-domain filtering according to any of claims 8, 9 or 11, wherein said transmitting the polarization-rotated and second phase-modulated first signal light and the non-phase-modulated second signal light to a first port comprises:

rotating the polarization of the second signal light by 90 degrees to obtain the second signal light without phase modulation; transmitting the first signal light which is subjected to polarization rotation and secondary phase modulation and the second signal light which is not subjected to phase modulation to the first port;

rotating the polarization of the second signal light by 90 degrees to obtain the second signal light without phase modulation; transmitting the first signal light without phase modulation and the second signal light without phase modulation to the second port.

13. A method of time-domain filtering according to any of claims 8, 9 or 11, wherein said transmitting the polarization-rotated and second phase-modulated first signal light and the non-phase-modulated second signal light to a first port comprises:

performing first attenuation on the second signal light to obtain first attenuated second signal light; rotating the polarization of the second signal light after the first attenuation by 90 degrees to obtain second signal light which is subjected to the first attenuation and polarization rotation; attenuating the second signal light which is subjected to the first attenuation and polarization rotation to obtain the second signal light which is not subjected to the phase modulation, and sending the first signal light which is subjected to the polarization rotation and the second phase modulation and the second signal light which is not subjected to the phase modulation to the first port;

performing first attenuation on the second signal light to obtain first attenuated second signal light; rotating the polarization of the second signal light after the first attenuation by 90 degrees to obtain second signal light which is subjected to the first attenuation and polarization rotation; and attenuating the second signal light which is subjected to the first attenuation and polarization rotation to obtain the second signal light which is not subjected to the phase modulation, and sending the first signal light which is not subjected to the phase modulation and the second signal light which is not subjected to the phase modulation to the second port.

14. The time-domain filtering method of any one of claims 8, 9 or 11, wherein the signal light is a quantum optical signal, the first signal light is a first quantum optical signal, and the second signal light is a second quantum optical signal; the first port is connected with a quantum optical signal receiver;

the acquiring the indication information and generating the pulse pump light according to the indication information includes:

receiving a synchronous optical signal;