WO2024001688A1

WO2024001688A1 - Passive communication terminal, passive communication system, and passive communication method

Info

Publication number: WO2024001688A1
Application number: PCT/CN2023/098510
Authority: WO
Inventors: 侯小珂; 傅正华; 李惠萍; 王晶; 仇晓明; 陆海强; 王文斌; 鲍志慧
Original assignee: 华为技术有限公司
Priority date: 2022-06-28
Filing date: 2023-06-06
Publication date: 2024-01-04
Also published as: CN117353817A

Abstract

Embodiments of the present application provide a passive communication terminal, system and method. The passive communication terminal comprises passive pickup devices. Each passive pickup device comprises a beam shaping part and a diaphragm, the diaphragm and the beam shaping part are arranged at an interval, and the beam shaping part is used for shaping first light received by the passive pickup device, and reflecting part of the first light to form first reflected light and transmitting part of the first light to form transmitted light. The diaphragm is used for vibrating under the action of sound waves at a pickup pending position to generate a vibration signal, and reflecting the transmitted light to form second reflected light. The second reflected light is loaded with the vibration signal, and the first reflected light and the second reflected light interfere with each other to form a coherent light signal. The objectives of normal signal transmission and long-distance communication during power outage in underground or other special scenarios are achieved, and the problem that normal signal transmission cannot be achieved or long-distance communication cannot be achieved during power outage in underground or other special scenarios is solved.

Description

Passive call terminal, passive call system and passive call method

This application requests the priority of the Chinese patent application submitted to the China Patent Office on June 28, 2022, with the application number 202210742858.X and the application name "Passive call terminal, passive call system and passive call method", which The entire contents are incorporated herein by reference.

Technical field

The embodiments of the present application relate to the field of communication technology, and in particular to a passive communication terminal, a passive communication system and a passive communication method.

Background technique

With the development of information technology, underground coal mine automated monitoring technology and communication technology have been significantly improved.

Existing various underground business systems in coal mines (such as data acquisition systems, personnel positioning systems, and communication systems, etc.) often use sensors to collect signals, and the signals are transmitted to control terminals above the mine through cables or wireless technology. However, due to the harsh conditions in coal mines, During the mining process, there are threats from natural disasters such as gas, roof, and water penetration. Once an accident occurs, it is easy to cause a power outage. The power outage will cause the underground sensors and cables to not work properly, making it impossible to collect underground signals. When using wireless methods, the communication distance is affected, and some active repeaters need to be added during transmission. However, when the power is cut off, active repeaters and underground terminals (such as sensors) cannot work. For some emergency communications, It cannot support long-distance communication, so it causes great inconvenience to underground fault diagnosis or rescue.

Therefore, how to achieve normal signal transmission underground or in other special scenarios (such as strong electromagnetic fields, high jets, flammable and explosive) when a power outage occurs has become an urgent problem that needs to be solved.

Contents of the invention

The embodiments of the present application provide a passive call terminal, a passive call system and a passive call method, which achieve the purpose of normal signal transmission and long-distance communication when power is outage in underground or other special scenarios, and solve the existing problems of underground or other special scenarios. In special scenarios, normal signal transmission or long-distance communication cannot be achieved when a power outage occurs.

The first aspect of this application provides a passive call terminal, including: a passive pickup, the passive pickup is arranged at a position to be picked up; the passive pickup includes a beam shaping member and a diaphragm, and the diaphragm and the beam shaping member are spaced apart , the beam shaping component is used to shape the first light received by the passive pickup, reflect part of the first light to form the first reflected light, and transmit part of the first light to form the transmitted light; the diaphragm is used Vibration occurs under the action of sound waves at the position to be picked up to generate a vibration signal, and the transmitted light is reflected to form a second reflected light. The second reflected light is loaded with a vibration signal, and the first reflected light and the second reflected light interfere with each other to form Coherent light signals.

The passive call terminal provided by the embodiment of the present application includes a passive pickup, and the passive pickup includes a beam shaping member and a diaphragm. The diaphragm is spaced apart from the beam shaping member. The beam shaping member is used to adjust the beam received by the passive pickup. beam into Shape the beam to reduce the divergence angle of the beam and improve the coupling efficiency after the beam is reflected. The diaphragm of the passive pickup is used to vibrate under the action of sound waves or other vibrations and generate a vibration signal, and the passive pickup first reflects part of the received light through the beam shaping member to form the first reflected light, and the transmitted light is Part of the light from the beam shaper is reflected again to form a second reflected light. The second reflected light is loaded with a vibration signal. The first reflected light and the second reflected light interfere with each other to form a coherent light signal. The coherent light signal is coupled to the optical fiber for transmission. In this way The remote-end (such as the bottom of a coal mine) sound or vibration signal is picked up through coherent optical signals, and the coherent optical signals are transmitted to the uplink pickup unit through the optical fiber, achieving the purpose of uplink passive pickup and improving the coupling efficiency. The source pickup does not need to be electrically connected to the power supply when working. In this way, the normal transmission of signals in coal mines or other special places is realized during power outages, thereby achieving timely positioning and monitoring of remote passive call terminals based on the received signals. This will help in timely fault diagnosis or personnel search and rescue. In addition, because passive pickups are passive, they have the advantages of anti-electromagnetic interference, safety and reliability, and are especially suitable for situations such as strong electromagnetic fields, high radio frequencies, flammable and explosive situations, such as high-voltage substations where coal mine gas causes underground power outages and strong electromagnetic fields. Work in other scenarios.

In a possible implementation, the ferrule has a first optical fiber passing through it;

One end of the ferrule and the beam shaping member are opposite to each other, and there is a gap between the beam shaping member and the ferrule. The gap is filled with filler. The filler bonds the beam shaping member and the ferrule, and the refractive index of the filler is consistent with the ferrule. Match the refractive index of the beam shaper.

In a possible implementation, the side of the beam shaping member facing the ferrule is a bevel, and the first optical fiber and the end of the ferrule facing the beam shaping member are both inclined surfaces parallel to the bevel.

In a possible implementation, the side of the diaphragm facing the beam shaping member has a first reflective surface; the end of the beam shaping member facing the diaphragm has a second reflective surface; the second reflective surface of the beam shaping member is in contact with the third side of the diaphragm. There is a cavity between the first reflective surfaces; the second reflective surface is used to reflect part of the first light to form the first reflected light, and to transmit part of the first light to form the transmitted light; the first reflective surface is used to The transmitted light is reflected to form a second reflected light.

In a possible implementation, the side of the beam shaping member facing the diaphragm and the side of the diaphragm facing the cavity are two parallel planes;

And the distance between the side of the beam shaping member facing the diaphragm and the first reflective surface of the diaphragm is 400-1000 μm.

In a possible implementation, the passive pickup further includes: a packaging fastener, the ferrule of the passive pickup is located in one end of the packaging fastener; and the diaphragm of the passive pickup is located on the other end of the packaging fastener. At one end; the beam shaper is located between the ferrule and diaphragm.

In a possible implementation, the packaging fastener includes: a first sleeve and a second sleeve located at one end of the first sleeve;

The ferrule and beam shaping member are both fixed in the second sleeve;

The diaphragm is located at the port at the other end of the first sleeve.

In a possible implementation, one of the first sleeve and the diaphragm of the passive pickup is provided with a through hole communicating with the cavity.

In a possible implementation, the beam shaping member is a light collimating lens.

In a possible implementation, the side of the diaphragm of the passive pickup facing the beam shaping member has a reflective film; and the reflectivity of the reflective film is ≥95%.

In a possible implementation, an optical film is provided on a side of the beam shaping member facing the diaphragm of the passive pickup;

The reflectivity of optical films ranges from 10-60%.

In a possible implementation, the method further includes: a first sound-generating component, the first sound-generating component is used to produce sounds according to the received audio signal.

In a possible implementation, the first sound-generating component includes: a photovoltaic conversion unit and a sound-generating component. The input end of the photovoltaic conversion unit is used to receive the second light, and the second light is loaded with an audio signal. The output end of the photovoltaic conversion unit Connected to the sound-emitting component; the photovoltaic conversion unit is used to convert the received second light into an electrical signal, so that the sound-emitting component emits sound according to the audio signal.

In a possible implementation, the photovoltaic conversion unit includes a back electrode, an absorption layer, a window layer and a transparent electrode layer stacked from bottom to top.

In a possible implementation, the method further includes: a lens, which is provided on the light incident side of the photovoltaic conversion unit.

A second aspect of the present application provides a passive call system, including N passive call terminals as described above, and an uplink pickup unit. The uplink pickup unit is connected to the N passive call terminals through optical fiber components; the uplink pickup unit The sound unit is used to emit the first light to the passive pickup, and receive the coherent optical signal returned from the passive pickup of the passive call terminal, so that the uplink pickup unit performs signal processing according to the received coherent optical signal to output a voice signal. ; N is an integer greater than or equal to 1.

The passive communication system provided by the embodiment of the present application includes a passive pickup and an uplink pickup unit, uses the passive pickup to pick up the sound or vibration signal from the far end (such as the bottom of a coal mine), and transmits the signal to the uplink pickup unit through optical fiber. unit, since the passive pickup does not need to be electrically connected to the power supply, this enables normal transmission of signals during power outages in coal mines or other special places, thereby achieving timely positioning and monitoring of remote passive call terminals based on the received signals. , which in turn helps timely fault diagnosis or personnel search and rescue, and realizes the role of uplink passive sound pickup. In addition, since passive pickups and optical fiber components are passive, they have the advantages of anti-electromagnetic interference, safety and reliability, and can be widely used in strong electromagnetic fields, high radio frequencies, flammable and explosive situations, etc., with low cost and reduced signal attenuation, thus It can be used for emergency calls in coal mines, highways, railways, etc. In addition, the passive pickup includes a beam shaping component, which improves the coupling efficiency of the passive pickup after the beam is reflected, thereby making the sound pickup effect better.

In a possible implementation, it also includes: a downlink sound transmission unit, the downlink sound transmission unit is used to emit a second light to the passive call terminal, the second light is loaded with an audio signal, so that the first light of the passive call terminal The sound-generating component produces sound based on the audio signal.

In a possible implementation, it also includes: an audio input unit, the audio input unit is connected to the downlink sound transmission unit;

The audio input unit is used to input audio signals to the downstream sound transmission unit.

In a possible implementation, the method further includes: a second sound-generating component, and the second sound-generating component is electrically connected to the uplink pickup unit.

In a possible implementation, the uplink pickup unit includes: a light source, an optical circulator, a beam splitter, a photodetector array, and a signal processing module, where the light source is used to generate the first light;

One port of the optical circulator is connected to the light source, and the other port of the optical circulator is used to connect to the optical fiber component. The optical splitter is connected to the third port of the optical circulator; the optical detector array is connected to the signal processing module, and the optical The detector array is used to receive coherent optical signals and convert the coherent optical signals into electrical signals.

In a possible implementation, the uplink pickup unit further includes: an optical amplifier, and the optical amplifier is provided between the optical circulator and the optical splitter.

In a possible implementation, the downlink sound transmission unit includes: a modulation module and a laser, and the modulation unit and the laser The laser is connected to one end of the optical fiber assembly; the modulation unit is used to modulate and load the audio signal on the laser; the laser is used to emit the second light loaded with the audio signal to the passive call terminal.

In a possible implementation, it also includes: a broadcast terminal, the broadcast terminal is located at a position to be picked up, and the broadcast terminal is connected to the optical fiber component.

In a possible implementation, the broadcast terminal includes: a light detector, an amplifier and a speaker; the light detector is connected to the output end of the optical fiber assembly, the light detector is connected to the amplifier; and the speaker is connected to the amplifier.

In a possible implementation, the broadcast terminal further includes a battery, and the battery is electrically connected to the light detector and the speaker respectively.

In a possible implementation, it also includes: an optical fiber component, which at least includes: a second optical fiber and an optical splitter;

One end of the optical splitter is connected to one end of the second optical fiber, and the other end of the optical splitter is connected to the passive communication terminal.

In a possible implementation, the optical fiber component further includes: an optical multiplexer, one end of the optical multiplexer is connected to both the uplink pickup unit and the downlink sound transmission unit of the passive communication system; the other end of the optical multiplexer is connected to the second The other end of the fiber is connected.

In a possible implementation, the number of optical splitters is one or more. When there is one optical splitter, one optical splitter is connected to N passive communication terminals; when the optical splitter is When there are multiple optical splitters, multiple optical splitters are arranged in series, and one optical splitter is connected to one or more terminals among the N passive communication terminals.

In a possible implementation, the passive communication system further includes: a power supply unit, which is connected to both the uplink sound pickup unit and the downlink sound transmission unit of the passive communication system.

The third aspect of this application provides a passive calling method, which includes:

The first light is emitted to the passive communication terminal, the passive communication terminal reflects part of the first light to form the first reflected light, and the passive communication terminal transmits part of the first light and then reflects it to form the second reflected light, And the second reflected light is loaded with a vibration signal generated by the vibration of the passive call terminal, and the first reflected light and the second reflected light interfere with each other to form a coherent light signal; receive the coherent light signal returned from the passive call terminal, and based on the coherent light signal The vibration signal in the speaker outputs a voice signal.

The passive call method provided by the embodiment of the present application realizes the function of passive and long-distance sound pickup between the far end (such as underground coal mine) and the near end (central control equipment). This call method can be used in coal mines or other special occasions. When there is a power outage, the sound under the coal mine can be picked up, realizing the function of long-distance and passive sound pickup during a power outage. The location to be picked up can be monitored and positioned in a timely manner, which is helpful for fault diagnosis or Personnel rescue.

In a possible implementation, the method further includes: emitting a second light to the passive call terminal, and the second light is loaded with an audio signal, so that the passive call terminal makes a sound based on the audio signal.

In this way, the function of passive two-way communication is realized. When used in coal mines or other special occasions, two-way communication between the mine and the underground can be realized when the power is cut off, so that when an accident occurs, the pickup position can be monitored in time. Positioning helps achieve fault diagnosis or personnel rescue.

Description of drawings

Figure 1 is a block diagram of a passive communication system provided by an embodiment of the present application;

Figure 2 is a schematic diagram of a passive call terminal provided by an embodiment of the present application;

Figure 3 is a schematic cross-sectional structural diagram of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 4 is another schematic cross-sectional structural diagram of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 5 is a curve corresponding to parameters of the cavity of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 6 is a schematic diagram of the reflection and transmission of the first light in a passive communication system provided by an embodiment of the present application;

Figure 7 is a schematic diagram of the cavity length and reflectivity curve of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 8 is a schematic diagram of the cavity length and FSR curve of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 9 is a schematic diagram of the cavity length and reflectivity curve of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 10 is a schematic curve diagram of the cavity length and coupling efficiency of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 11 is another cross-sectional structural schematic diagram of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 12 is another schematic cross-sectional structural diagram of a passive pickup in a passive communication system provided by an embodiment of the present application;

Figure 13 is another schematic diagram of a passive call terminal provided by an embodiment of the present application;

Figure 14 is a schematic structural diagram of a photovoltaic conversion unit in a passive communication system provided by an embodiment of the present application;

Figure 15 is a schematic structural diagram of a photovoltaic conversion unit and lens in a passive communication system provided by an embodiment of the present application;

Figure 16 is a schematic structural diagram of a passive communication system provided by an embodiment of the present application;

Figure 17 is a schematic curve diagram of a passive communication system using a phase demodulation mechanism according to an embodiment of the present application;

Figure 18 is a schematic curve diagram of a passive communication system using a three-wavelength demodulation mechanism provided by an embodiment of the present application;

Figure 19 is a schematic circuit diagram of a passive communication system using a three-wavelength demodulation mechanism provided by an embodiment of the present application;

Figure 20 is another structural schematic diagram of a passive communication system provided by an embodiment of the present application;

Figure 21 is another structural schematic diagram of a passive communication system provided by an embodiment of the present application;

Figure 22 is a schematic diagram of the modulation of audio signals in a passive call system provided by an embodiment of the present application;

Figure 23 is a schematic diagram of another modulation of audio signals in a passive call system provided by an embodiment of the present application;

Figure 24 is another structural schematic diagram of a passive communication system provided by an embodiment of the present application;

Figure 25 is a schematic structural diagram between each optical splitter and channels provided by the embodiment of the present application;

Figure 26 is a schematic diagram of a multi-level networking of a passive communication system provided by an embodiment of the present application;

Figure 27 is a schematic diagram of a passive communication system using secondary filtering provided by an embodiment of the present application;

Figure 28 is a schematic structural diagram of a passive communication system in single-stage networking provided by an embodiment of the present application;

Figure 29 is another structural schematic diagram of a passive communication system provided by an embodiment of the present application;

Figure 30 is another structural schematic diagram of a passive communication system provided by an embodiment of the present application;

Figure 31 is a schematic flow chart of a passive calling method provided by an embodiment of the present application;

Figure 32 is another schematic flowchart of a passive calling method provided by an embodiment of the present application.

Explanation of reference symbols:
10. Central control equipment; 11. Uplink pickup unit; 111. Light source; 112. Optical circulator; 113. Optical splitter;
114. Signal processing module; 115. Photodetector array; 12. Downlink sound transmission unit; 121. Modulation module; 122. Laser; 13. Power supply unit; 14. Second sound-emitting component; 15. Audio input unit;
20. Optical fiber component; 21. Optical combiner; 22. Second optical fiber; 23. Optical splitter;
30. Passive call terminal; 31. Passive pickup; 311. Packaging fasteners; 3111. First sleeve; 3112.
Second sleeve; 312, ferrule; 313, diaphragm; 3131, first reflective surface; 3113, cavity; 3121, end face; 314, Beam shaping member; 3141, second reflective surface; 3142, end face; 315, first optical fiber; 3151, tail end face; 316, filler; 32, first sound-emitting component; 321, photovoltaic conversion unit; 322, sound-emitting component;
40. Broadcast terminal; 41. Light detector; 42. Amplifier; 43. Amplifier; 44. Battery.

Detailed ways

Commonly used communication methods in flammable and explosive places such as coal mines are: wired communication or wireless communication. In wired communication, cables are often connected to sensors installed underground. However, once a power outage occurs, the sensors installed underground cannot work, thus It is impossible to obtain underground signals. For wireless communication, the communication distance is short, and active repeaters are often required (that is, the repeaters need to be connected to the power supply). However, when the power is cut off, the active repeaters and underground sensors cannot work. , thus making it impossible to obtain underground signals in time, making it impossible to quickly locate, diagnose faults, or search and rescue personnel.

To this end, in order to solve the above problems, the passive call terminal and the passive call system provided by the embodiments of the present application include a passive pickup 31, and use the diaphragm of the passive pickup 31 to vibrate under the action of sound waves or other vibrations and generate vibration signal, and the passive pickup 31 first reflects part of the received light to form a first reflected light, and reflects part of the light again after being transmitted to form a second reflected light, and the second reflected light is loaded with a vibration signal, Finally, the first reflected light and the second reflected light interfere to form a coherent optical signal. In this way, the far-end (such as the bottom of a coal mine) sound or vibration signal is picked up through the coherent optical signal, and the coherent optical signal is transmitted to the uplink pickup unit through the optical fiber. , achieves the purpose of uplink passive pickup. Since the passive pickup 31 does not need to be electrically connected to the power supply when working, in this way, the normal transmission of signals during power outages in coal mines or other special places is achieved, thereby achieving the desired effect based on the received signal. The timely positioning and monitoring of the passive communication terminal 30 at the remote end (such as the bottom of a coal mine or a flammable and explosive location) can further contribute to timely fault diagnosis or personnel search and rescue. In addition, because the passive pickup 31 is passive, it has the advantages of anti-electromagnetic interference, safety and reliability, and is especially suitable for situations such as strong electromagnetic fields, high radio frequencies, flammable and explosive situations, such as underground power outages caused by coal mine gas, and high voltages with strong electromagnetic fields. Work in scenarios such as transformer substations.

Therefore, the passive call terminal and passive call system provided by the embodiments of the present application can be applied to emergency communications in flammable and explosive places such as coal mines, emergency telephones on highways, railways, etc., or can also be used in strong electromagnetic fields. high-voltage substations and other places. Of course, the passive call terminal and passive call system provided by the embodiments of the present application can also be applied to other call places where sound pickup and sound transmission are required.

The following takes the application of passive communication systems in coal mines as an example for detailed explanation.

As shown in FIG. 1 , the passive call system provided by the embodiment of the present application may include: N passive call terminals 30 and uplink sound pickup units 11 . The uplink sound pickup unit 11 can be connected to the N passive call terminals 30 through the optical fiber assembly 20. For example, the uplink sound pickup unit 11 is connected to one end of the optical fiber assembly 20, and the other end of the optical fiber assembly 20 is connected to the N passive call terminals 30. .

Where N is an integer greater than or equal to 1, for example, N can be 1, 2, or any integer above 2. Among them, the number of passive call terminals 30 can be set according to the number of positions to be picked up. For example, if there are 8 positions to be picked up, the number of passive call terminals 30 can also be 8. Of course, one to be picked up One passive call terminal 30 can be set at a position, or more than two passive call terminals 30 can be set at a position to be picked up.

The uplink sound pickup unit 11 is used to emit the first light to the passive communication terminal 30 (see Figure 2 below), and receive coherent optical signals returned from the passive communication terminal 30 . As shown in Figure 1, the passive call terminal 30 includes a passive pickup 31. The diaphragm 313 (see Figure 3) of the passive pickup 31 is used to vibrate and generate a vibration signal under the action of sound waves at the location to be picked up. The passive The diaphragm 313 of the pickup 31 reflects the first light to form a vibration signal loaded with it. coherent optical signal. The uplink pickup unit 11 performs signal processing according to the received coherent optical signal and outputs a voice signal. This completes the function of picking up the sound at the target pickup position.

In the embodiment of the present application, the uplink passive sound pickup process may be: the uplink sound pickup unit 11 emits a first light, and the first light may be a wide-spectrum light, and the first light is transmitted to the passive call terminal 30 through the optical fiber assembly 20 The passive pickup 31 reflects part of the first light for the first time, and reflects the rest of the first light for the second time after being transmitted. During the reflection process, when the sound to be picked up is When there is sound at the location, the passive pickup 31 vibrates under the action of the sound and generates a vibration signal. The vibration signal is loaded on the second reflected light. The second reflected light loaded with the vibration signal is different from the first reflected light. The reflected light is coupled to the optical fiber component 20 and interferes to form a coherent optical signal. The coherent optical signal is transmitted to the uplink pickup unit 11 through the optical fiber component 20, and a voice signal is output according to the vibration signal in the coherent optical signal to complete the pickup process.

In the embodiment of the present application, since the signal attenuation of the optical fiber is lower than that of the cable, and the laying cost of the optical fiber is lower than that of the cable, the passive communication system provided by the embodiment of the present application reduces the cost of the system and the attenuation of the signal, thereby reducing the attenuation of the signal. It is more suitable for emergency calls in coal mines, highways, railways, etc.

The passive call system provided by the embodiment of the present application includes a passive pickup 31 and an uplink pickup unit 11, and the passive pickup 31 does not need to be connected to the power supply, thereby achieving the purpose of passive pickup and avoiding the need for remote sound pickup in coal mines and highways. In special occasions such as railways and railways, signal transmission cannot be carried out when the power is cut off. In addition, in the embodiment of the present application, since the passive pickup and the optical fiber assembly 20 are both passive devices, the passive call system provided by the embodiment of the present application can support a transmission distance of 20km, realizing long-distance signals. transmission effect.

The passive communication terminal 30 provided by the embodiment of the present application is first described in detail below.

Among them, as shown in Figure 2, each passive call terminal 30 includes: a passive pickup 31. The passive pickup 31 is arranged at a position to be picked up. In the embodiment of the present application, the position to be picked up may be underground in a coal mine. In the alleyway. Neither the passive pickup 31 nor the optical fiber assembly 20 is electrically connected to the power supply, and both are passive devices. The passive pickup 31 is used to pick up the sound underground and load the sound as a vibration signal onto the reflected light. Finally, the reflected light loaded with the vibration signal is coupled to the optical fiber assembly 20, passes through the optical fiber assembly 20 and is transmitted to the uplink pickup unit 11. Monitoring and positioning underground based on sound can help with fault diagnosis or personnel search and rescue.

The structure of the passive pickup 31 provided by the embodiment of the present application can be referred to as shown in Figure 3.

As shown in Figure 3, the passive pickup 31 includes: a packaging fastener 311, a ferrule 312 and a diaphragm 313. The packaging fastener 311 can be a tubular structure with both ends open, and the ferrule 312 is located on the packaging fastener. One end of the component 311 is open, and the first optical fiber 315 is inserted into the ferrule 312. As shown in Figure 3, the tail end surface 3151 of the first optical fiber 315 extends to the end surface 3142 of the ferrule 312 and is in contact with the end surface 3142 of the ferrule 312. Flush, the other end of the first optical fiber 315 passes through the ferrule 312 and is used to be connected to the optical fiber assembly 20 (for example, to the optical splitter 23).

In a possible implementation, as shown in FIG. 3 , the packaging fastener 311 includes: a first sleeve 3111 and a second sleeve 3112 located at one end of the first sleeve 3111 , a ferrule 312 and a beam shaping member. 314 are fixed in the second sleeve 3112, and the diaphragm 313 is provided at the port at the other end of the first sleeve 3111. Among them, the first sleeve 3111 can be a stainless steel sleeve, the second sleeve 3112 can be a glass sleeve, and the second sleeve 3112 can play a role in fixing the ferrule 312 and the beam shaping member 314. In this way, the ferrule 312 The beam shaping member 314 is fixed in the first sleeve 3111 through the second sleeve 3112.

As shown in FIG. 3 , the diaphragm 313 is disposed at the opening at the other end of the packaging fastener 311 . For example, the diaphragm 313 and the ferrule 312 are respectively located in the openings at both ends of the packaging fastener 311 . Among them, between the diaphragm 313 and the ferrule 312 There is a cavity 3113, and the side of the diaphragm 313 facing the cavity 3113 has a first reflective surface 3131. Among them, the side of the first optical fiber 315 facing the diaphragm 313 is a vertical plane. When the first light is transmitted through the optical component in the first optical fiber 315 to the tail end face 3151 of the first optical fiber 315, part of the first optical fiber 315 is at the tail end face. 3151 emits sound and reflects, part of the first optical fiber 315 is projected out from the tail end surface 3151, enters the cavity 3113, and is reflected by the first reflective surface 3131.

Among them, the sound pickup process of the passive pickup 31 provided by the embodiment of the present application is: the uplink pickup unit 11 sends the first light, and the first light is transmitted to the first optical fiber 315 through the optical fiber assembly 20. When the first optical fiber 315 is transmitted to When the tail end face 3151 of the first optical fiber 315 is turned on, the tail end face 3151 reflects part of the first light to form the first reflected light. Part of the first light is transmitted from the tail end face 3151 into the cavity 3113 and illuminates the oscillator. The first reflective surface 3131 of the film 313 reflects the transmitted first light for a second time to form a second reflected light. The second reflected light is reflected at the tail end surface of the first optical fiber 315 There is continuous reflection between 3151 and the first reflective surface 3131, and part of the second reflected light is coupled to the first optical fiber 315 through the tail end surface 3151 of the first optical fiber 315. When the light is reflected back and forth between the tail end surface 3151 of the first optical fiber 315 and the first reflective surface 3131, if there is sound or vibration at the pickup position, the diaphragm 313 will vibrate, and the vibration of the diaphragm 313 will cause the air to vibrate. The volume within the cavity 3113 changes, causing the phase or optical path difference of the second reflected light to change. In addition, since the light is reflected on the first reflective surface 3131 of the diaphragm 313, the light reflected by the first reflective surface 3131 will be loaded with a vibration signal generated by the vibration of the diaphragm 313, so that the first reflected light is different from the second reflected light. The reflected light couples and interferes on the first optical fiber 315 to form a coherent light signal, and the coherent light signal is loaded with a vibration signal of the vibration of the diaphragm 313. In this way, the sound or vibration at the location to be picked up is loaded on the coherent light signal, and It is transmitted to the uplink sound pickup unit 11, the coherent optical signal is processed, and finally the voice signal is output, and the sound or vibration at the position to be picked up is restored.

Among them, in the embodiment of the present application, the diaphragm 313 can be a micro-electro-mechanical system (Micro-Electro-Mechanical System, MEMS) film, a metal film, a polymer film, etc.

The first light ray is fixed through the ferrule 312 and the packaging fastener 311 so that the tail end surface 3151 of the first optical fiber 315 and the diaphragm 313 have good parallelism. In this embodiment of the present application, the tail end surface 3151 of the first optical fiber 315 and the first reflective surface 3131 of the diaphragm 313 may be two parallel surfaces parallel to each other.

Among them, the ferrule 312 and the tail end surface 3151 of the first optical fiber 315 can protrude from the end surface of the second sleeve 3112 as shown in Figure 3 and extend into the cavity 3113, so that the cavity length L of the cavity 3113 can be adjusted. Of course, , in some examples, as shown in FIG. 4 , the ferrule 312 and the tail end surface 3151 of the first optical fiber 315 can also be flush with the end surface of the second sleeve 3112 facing the cavity 3113 .

In the embodiment of the present application, it should be noted that since the light is reflected back and forth between the tail end surface 3151 of the first optical fiber 315 and the first reflective surface 3131 of the diaphragm 313, in the embodiment of the present application, as shown in Figure 3 , the cavity length L of the cavity 3113 in the passive pickup 31 is the distance between the tail end surface 3151 of the first light ray and the first reflective surface 3131 of the diaphragm 313 .

In the embodiment of the present application, the cavity 3113 in the passive pickup 31 is a Fabry-Parot resonant cavity (FP cavity), and the tail end surface 3151 of the first light ray and the first reflective surface 3131 of the diaphragm 313 constitute a Fabry-Perot resonant cavity (FP cavity). Two parallel planes of Paro cavity (FP cavity).

Among them, the key characteristic parameters of the FP cavity are Free Spectral Range (FSR), insertion loss, contrast, and finesse. Among them, FSR needs to meet the system channel number requirements. This value directly affects the cavity length and insertion loss. The system link loss requirements also need to be met. The higher the reflectivity, the smaller the insertion loss. The size of the contrast directly affects the amplitude of the added speech signal. A large contrast means that the dynamic range of the speech signal is large, and contrast is generally required. >20dB. The size of the contrast is related to the energy reflected back to the optical fiber. When the return energy of the two reflective surfaces is close to matching, a larger contrast can be obtained. Among them, the calculation methods of FSR, insertion loss, and contrast can be seen in the curve shown in Figure 5.

Figure 6 is a theoretical model diagram of multi-beam interference of a standard optical fiber FP cavity. See Figure 6. The FP cavity is a parallel plane with a distance L. Assume that the refractive index of the medium between the parallel planes is n0, the refractive index of both sides is n, and the beam a is incident at an angle i and is continuously reflected and transmitted between the two interfaces. Among them, a1, a2, a3, etc. are reflected lights. Multi-beam interference of reflected light occurs to form a reflection interference spectrum. Multi-beam interference occurs when b1, b2, b3, etc. are transmitted. A transmission interference spectrum is formed.

According to the double-beam interference theory, when the incident angle i is zero, the formula for the interference light intensity composed of the reflected beam is (1):

where φ is the phase difference between the two reflected lights, and its formula is:
φ＝(4πn ₀ L)/λ (2)

It is determined by the cavity length L, the refractive index of the cavity medium n ₀ and the wavelength λ of the incident light. (1) In the formula, R ₁ and R ₂ are the reflectivity of the two reflecting surfaces respectively. It can be seen from formulas (1) and (2) that reflectivity is related to cavity length, wavelength, medium refractive index, and reflectivity. That is, through changes in the cavity length, intensity changes can be achieved. The intensity changes reflect the vibration information of the cavity length and respond to external sounds or pressures.

Assume that the refractive index of the fixed medium is 1, the reflectivity R ₁ and R ₂ are both 4%, and the cavity lengths are 100 μm and 600 μm respectively. Figure 7 of the change of reflectivity with wavelength is obtained. See Figure 7. The dotted line L7 is the value of cavity 3113. The curves of different wavelengths and reflectivity when the cavity length L is 100 μm. The solid line L6 is the curve of different wavelengths and reflectivity when the cavity length L of the cavity 3113 is 600 μm. See Figure 7. The cavity length L of the cavity 3113 is When the cavity length is 100μm, the period is larger, and in the fixed wavelength range such as 1520~1570nm, it is more sparse, with only 4 periods; when the cavity length is 600um, the period is small, and there are 25 periods in the fixed wavelength range such as 1520~1570nm.

The parameter describing the period size is the Free Spectrum Range (FSR), which is used to represent the wavelength resolution capability of the FP cavity. Its formula is expressed as (3),

where λ ₀ is the average wavelength of broadband incident light, and L is the cavity length of the FP cavity. Its physical meaning is the interference period as shown in Figure 7. As shown in Figure 8, the larger the cavity length, the smaller the FSR.

It is also assumed that the refractive index of the fixed medium is 1, the reflectivity R ₁ and R ₂ are both 4%, the cavity length is 600 μm, and the incident wavelength is 1550 nm, as shown in Figure 9, when the cavity length ΔL is changed, the reflectivity also changes periodically. Variety.

Since the light emitted from the first optical fiber 315 has certain divergence, without considering the cavity coupling loss, the coupling efficiency ε formula of the FP cavity is (4):

Among them, n ₀ is the refractive index of the cavity medium, ω ₀ is the mode field radius of the Gaussian beam of the single-mode fiber, L is the initial cavity length, and λ is the wavelength of the incident light. Its relationship with the initial cavity length is the largest, and the relationship simulation is shown in Figure 10. It can be seen that as the initial cavity length increases, the coupling efficiency decreases rapidly and the loss increases sharply.

When the system is working, each channel needs to occupy one FSR. If it is to be expanded to multiple channels, it must occupy multiple FSRs. However, the wavelength resources in actual use are limited, such as C-band 1530~1565nm. If you want to achieve enough channels in the limited band resources, you need to find ways to reduce FSR. As shown in Figure 8, increasing the cavity length L can effectively reduce the FSR, but as shown in Figure 10, the coupling efficiency decreases and the loss increases. For example, if the central wavelength is 1550 nm, the medium refractive index n ₀ is 1, and the cavity length is 100 μm (FSR = 12 nm), if a single-mode optical fiber (i.e., the first optical fiber 315) and the diaphragm 313 are directly used to form the FP cavity (i.e., the first light ray When the tail end surface 3151 and the first reflective surface 3131 of the diaphragm 313 form two parallel surfaces of the FP cavity), the reflectivity of the single-mode optical fiber end surface 3142 is about 4%. At this time, the loss is 12~15dB, corresponding to the C-band only Supports 3 channels; if the cavity length is 600μm (FSR=2nm), it can support 17 channels corresponding to the C-band, but the loss is >25dB, which cannot meet the system requirements. Therefore, the key to expanding multi-channel is to increase the coupling efficiency and loss to meet the system requirements while increasing the cavity length L.

To this end, in order to improve the coupling efficiency, as shown in FIG. 11 , the passive pickup 31 may also include: a beam shaping member 314 , the beam shaping member 314 is used to shape the beam (such as the first light) received by the passive pickup 31 , reduce the divergence angle of the beam and improve the coupling efficiency after beam reflection. The beam shaping member 314 reflects part of the first light to form the first reflected light, and transmits part of the first light to form the transmitted light. The passive pickup 31 reflects the transmitted light to form a second reflected light, the second reflected light is loaded with the vibration signal when the passive pickup 31 vibrates, and the first reflected light and the second reflected light are coupled to the first optical fiber 315, and the second reflected light is coupled to the first optical fiber 315. The first reflected light and the second reflected light interfere with each other to form a coherent optical signal that is transmitted to the uplink pickup unit 11 .

When the beam shaping member 314 is installed, as shown in FIG. 11 , the beam shaping member 314 can be fixed in the packaging fastener 311 . One end of the beam shaping member 314 facing the diaphragm 313 has a second reflective surface 3141 ; the beam shaping member 314 There is a cavity 3113 between the second reflective surface 3141 and the first reflective surface 3131 of the diaphragm 313. For example, the cavity 3113 is located between the second reflective surface 3141 and the first reflective surface 3131, and the second reflective surface 3141 and the first reflective surface 3131. A reflective surface 3131 is two parallel parallel surfaces of the cavity 3113 (ie, FP cavity). Therefore, the side of the beam shaping member 314 facing the diaphragm 313 and the side of the diaphragm 313 facing the cavity 3113 are two parallel planes.

Among them, the second reflective surface 3141 is used to reflect part of the first light to form a first reflected light, and to transmit part of the first light to form a transmitted light; the first reflective surface 3131 is used to reflect the transmitted light to form a The second reflected light; the first reflected light and the second reflected light interfere with each other and couple with the vibration signal to form a coherent light signal.

Among them, in the embodiment of the present application, the first reflected light, the transmitted light and the second reflected light can be seen in Figure 6. The first light can be light a, the first reflected light can be light a1, and the transmitted light can be point A and point A. The light between point C and the second reflected light can be the light between point C and point B, wherein the interference between the first reflected light and the second reflected light can be caused by the second reflected light being transmitted from the second reflective surface 3141 The light rays a2, a3, a4, _an , etc. and the first reflected light ray (for example, the light ray a1) are coupled to the first optical fiber 315 and interfere, forming a coherent optical signal.

In the embodiment of the present application, the working principle of the passive pickup 31 is as follows: As shown in FIG. 11 , the first light is emitted through the first optical fiber 315 and enters the beam shaping member 314 . At the second reflecting surface 3141 of the beam shaping member 314 The first reflection and projection occur, forming the first reflected light and the transmitted light. The first reflected light returns toward the first optical fiber 315 along the beam shaping member 314, and the transmitted light irradiates the first reflective surface 3131 of the diaphragm 313 for reflection. A second reflected light is formed. The second reflected light is reflected between the first reflective surface 3131 and the second reflective surface 3141. Part of the second reflected light passes through the beam shaping member 314 and returns toward the first optical fiber 315. When the sound to be picked up is When there is sound or vibration at the location, the diaphragm 313 vibrates and squeezes the cavity 3113, causing the phase of the second reflected light in the cavity 3113 to change. In addition, the second reflected light will be loaded based on the vibration of the diaphragm 313 during the reflection process. The vibration signal of the diaphragm 313, in this way, the first reflected light reflected by the second reflective surface 3141 of the beam shaping member 314 and the first reflected light reflected by the first reflective surface 3131 of the diaphragm 313 The second reflected light interferes after being coupled to the first optical fiber 315 to form a coherent light signal. After the coherent light signal is received by the photodetector array 115, it is demodulated by the signal processing module 114, and the vibration information of the diaphragm 313 can be obtained. That is, the sound at the position to be picked up is restored.

In the embodiment of the present application, by providing the beam shaping member 314, the first light emitted from the first optical fiber 315 and the reflected light can be shaped to reduce the divergence angle, thereby improving the coupling efficiency after the reflected light beam.

In the embodiment of the present application, through the interference of the first reflected light and the second reflected light, in this way, the second reflected light carrying the vibration signal and the first reflected light are superimposed, so that the light intensity of the formed coherent optical signal is enhanced. , In this way, when the uplink pickup unit 11 receives the coherent optical signal, it is convenient to demodulate the vibration signal.

In a possible implementation, as shown in FIG. 11 , if the first light emitted from the first optical fiber 315 directly irradiates the end face 3142 of the beam shaping member 314 , the first light will emit light at the end face 3142 of the beam shaping member 314 . Reflection reduces the amount of light transmitted by the first light into the beam shaping member 314. In this way, the first reflected light and the second reflected light after reflection are reduced, which is not conducive to the collection of vibration signals. For this reason, in order to reduce the beam shaping member 314 toward the reflection at the end face 3142 of one end of the first optical fiber 315. As shown in FIG. Bonded to the ferrule 312, the refractive index of the filler 316 matches the refractive index of the ferrule 312 and the beam shaper 314. For example, the refractive index of the filler 316 is between the refractive indexes of the ferrule 312 and the beam shaper 314. For example, if the refractive index of the ferrule 312 is 1.8 and the refractive index of the beam shaping member 314 is 1.5, then the refractive index of the filler 316 is between 1.5 and 1.8. In this way, the filler 316 plays a transition role in the refractive index between the ferrule and the beam shaper, and the filler 316 is bonded to the beam shaper 314 and the ferrule 312 respectively, so that the first light emitted from the first optical fiber 315 After passing through the filler 316, the beam can enter the beam shaping member 314, thereby reducing the reflection of the first light from the end surface 3142 of one end of the beam shaping member 314 facing the ferrule 312.

In the embodiment of the present application, the filler 316 can be a glue material, for example, the glue material can be a resin material, the ferrule 312 can be a ceramic material, and the beam shaping member 314 can be a lens. Therefore, the glue material only needs to have a reflectivity in the range of Any light-transmitting material with a reflectivity between ceramic and lens can be used.

In a possible implementation, in order to further reduce the reflection of the first light at the tail end surface 3151 of the first optical fiber 315 and the end surface 3142 of the beam shaping member 314, as shown in FIG. 11, the beam shaping member 314 faces the ferrule 312. The end surface 3142 of one end is an inclined surface, and the end of the first optical fiber 315 and the ferrule 312 facing the beam shaping member 314 is an inclined surface parallel to the inclined surface. For example, in some examples, the tail end surface 3151 of the first optical fiber 315 is an inclined surface, the angle between the tail end surface 3151 of the first optical fiber 315 and the horizontal plane may be 8°, and the end of the ferrule 312 faces the beam shaper 314 The included angle between the end surface 3121 and the horizontal plane is 8°, and the included angle between the end surface 3142 of one end of the beam shaping member 314 facing the ferrule 312 and the horizontal plane is 8°. In this way, the reflection of the first light by the tail end surface 3151 of the first optical fiber 315 and the end surface 3142 of the beam shaping member 314 can be further reduced.

It should be noted that in some examples, it is only necessary to arrange the tail end surface 3151 of the first optical fiber 315 and the end surface 3142 of the beam shaping member 314 toward one end of the ferrule 312 in parallel and at an angle, and the end surface 3121 of the ferrule 312 can be The arrangement is not parallel to the end surface 3142 of the beam shaping member 314 .

It should be noted that, in order to adjust the cavity length L of the cavity 3113, as shown in FIG. 11 , one end of the beam shaping member 314 facing the diaphragm 313 can protrude from one end of the second sleeve 3112, or, as shown in FIG. In some examples, as shown in FIG. 12 , one end of the beam shaping member 314 facing the diaphragm 313 may also be flush with the end surface 3142 of one end of the second sleeve 3112 .

In a possible implementation, one of the first sleeve 3111 and the diaphragm 313 is provided with a cavity 3113 communicating via holes (not shown). For example, a through hole can be provided in the first sleeve 3111, or a through hole can be provided in the diaphragm 313. By providing the through hole, the pressure inside and outside the cavity 3113 can be balanced, thereby facilitating the vibration of the diaphragm 313.

In a possible implementation, the beam shaping member 314 is a light collimating lens. For example, the light collimating lens may be a gradient index lens (G-lens).

In a possible implementation, the side of the diaphragm 313 facing the cavity 3113 has a reflective film (not shown), the reflective film forms the first reflective surface 3131, and the reflectivity of the reflective film is ≥95%, for example, the reflective film The reflectivity can be 98% or 96%, so as to ensure that the light irradiating on the first reflective surface 3131 of the diaphragm 313 can be fully reflected as much as possible and reduce the transmission from the diaphragm 313.

In a possible implementation, an optical film is provided on the side of the beam shaping member 314 facing the diaphragm 313, and the side of the optical film facing the ferrule 312 forms a second reflective surface 3141. The reflectivity of the optical film is between 10-60 %, for example, the reflectivity of the optical film can be 50%, or 55%, etc., thus ensuring that the second reflected light reflected by the first reflective surface 3131 of the diaphragm 313 can partially pass through the optical film and enter the beam shaping member 314, and then Interferes with the first reflected light to form a coherent light signal.

In a possible implementation, the distance between the side of the beam shaping member 314 facing the diaphragm 313 and the first reflective surface 3131 of the diaphragm 313 is 400-1000 μm. For example, as shown in FIG. 11, the beam shaping member 314 faces the diaphragm 313. The distance between one side of the diaphragm 313 and the first reflective surface 3131 of the diaphragm 313 is the cavity length L. Therefore, the cavity length L is 400-1000 μm. For example, the cavity length L can be 600 μm, or the cavity length L can also be is 800μm, so the period in Figure 7 is small, and there are more periods in a fixed wavelength range such as 1520~1570nm, so the FSR is small, and the C-band

Multiple channels can be expanded within 1530 to 1565nm, and the coupling efficiency is ensured through the beam shaping member 314. Therefore, when the cavity length is increased, the channels are expanded and the coupling efficiency is improved, so that the insertion loss of the system meets the system requirements.

Among them, the passive call terminal 30 provided in the embodiment of the present application is for the purpose of receiving audio signals. Therefore, as shown in Figure 13, each passive call terminal 30 may further include: a first sound-emitting component 32, a first sound-emitting component 32 may be set at a position to be picked up, or the first sound-emitting component 32 may be set at a position different from the position to be picked up, for example, a receiving position spaced apart from the position to be picked up in an underground tunnel. The sound-emitting component receives the second light, and the second light is loaded with an audio signal. The first sound-emitting component 32 emits sound based on the audio signal. In this way, the position to be picked up can obtain the transmitted audio signal from the well, thereby achieving the purpose of two-way communication, and more Conducive to fault diagnosis or personnel rescue.

Among them, the first sound-generating component 32 can be a low-power sound-generating component. For example, a photovoltaic cell can be used to drive the sound. In this way, during the two-way conversation, the passive call terminal 30 still does not need an additional power connection. A sound-emitting component 32 can normally receive the second light transmitted by the optical fiber component 20, thereby achieving the purpose of two-way passive communication.

Wherein, the first light and the second light have different wavelengths, and the second light can be a laser beam, or, in some examples, the first light and the second light can have the same wavelength, for example, both the first light and the second light can is the laser beam.

In one possible implementation, as shown in FIG. 13 , the first sound-generating component 32 includes a photovoltaic conversion unit 321 and a sound-generating component 322 . The input end of the photovoltaic conversion unit 321 is connected to one end of the optical fiber component 20 . The photovoltaic conversion unit The output end of 321 is connected to the sound-emitting element 322.

The photovoltaic conversion unit 321 is used to convert the second light transmitted by the optical fiber assembly 20 into an electrical signal. The sounding component 322 restores the converted electrical signal into an audio signal for output. In the embodiment of the present application, the photovoltaic conversion unit 321 can also supply power to the sound-emitting component 322, and the sound-emitting component 322 can emit sound when driven by the photovoltaic conversion unit 321. Need explanation It should be noted that in this embodiment of the present application, the sound-generating component 322 can be a low-power speaker. In this way, the photovoltaic conversion unit 321 is a photovoltaic cell, and the photovoltaic cell can drive the low-power speaker to produce sound.

By including the photovoltaic conversion unit 321 and the sound-emitting component 322, the first sound-emitting component 32 is a passive device that does not need to be connected to an external power supply. When a power outage occurs in a coal mine or other places, the first sound-emitting component 32 passes through the photovoltaic conversion unit 321 Providing power to the sounding part 322 ensures that the sounding part 322 can work normally when the power is cut off underground in the coal mine, thereby realizing passive two-way communication.

As shown in FIG. 14 , the photovoltaic conversion unit 321 includes a back electrode 3211 , an absorption layer 3212 , a window layer 3213 and a transparent electrode layer 3214 that are stacked from bottom to top. The photovoltaic conversion unit 321 may be a PN structure or a PIN structure. The photovoltaic conversion unit 321 may be a single junction structure or a multi-junction series structure to obtain the maximum output current. The multi-junction series structure may be a horizontal series connection or a vertical series structure.

The light-absorbing layer may be a layer structure made of any one of indium gallium arsenide (InGaAs), gallium arsenide (GaAs), indium gallium arsenide phosphorus (InGaAsP), silicon (Si) and other materials.

In a possible implementation, optical fibers are also used to connect the photovoltaic conversion unit 321 and the optical splitter. The photovoltaic conversion unit 321 can be directly coupled with the optical fiber. For example, the optical fiber can be directly coupled with the photovoltaic conversion unit 321 .

Or, in some examples, as shown in FIG. 15 , a lens 3215 is also included, and the lens 3215 is provided on the light incident side of the photovoltaic conversion unit 321 . In this way, the light emitted from the optical fiber enters the photovoltaic conversion unit 321 through the lens 3215, and the photovoltaic conversion unit 321 and the optical fiber are coupled through the lens 3215.

The lens 3215 and the photovoltaic conversion unit 321 can be provided independently, or the lens 3215 and the photovoltaic conversion unit 321 can be integrated into an overall structure.

By arranging the lens 3215, a certain distance can be separated between the optical fiber and the photovoltaic conversion unit 321, so that the optical fiber and the lines on the photovoltaic conversion unit 321 are less likely to interfere, thereby improving the coupling efficiency of the optical fiber and the photovoltaic conversion unit 321.

In the embodiment of the present application, as shown in FIG. 13 , the passive pickup 31 , the photovoltaic conversion unit 321 and the sound-emitting element 322 in each passive call terminal 30 can be packaged into an integral structure. For example, each passive call terminal 30 can It is an integrated device that can both pick up sounds and make calls. During setting, N passive call terminals 30 are set at corresponding positions to be picked up, and the passive call terminals 30 are passive devices.

The structure of the uplink pickup unit 11 will be described in detail below.

As shown in FIG. 16 , the uplink pickup unit 11 may include: a light source 111 , an optical circulator 112 , a spectrometer 113 , a photodetector array 115 and a signal processing module 114 . The light source 111 is used to generate the first light. The light source 111 may be Broad spectrum light source, the broad spectrum light source can be an amplified spontaneous emission (Amplified Spontaneous Emission, ASE) light source 111, or the broad spectrum light source can be a superluminescent tube.

The optical circulator 112 can be a three-port circulator, and the optical circulator 112 can realize one-way transmission of signals. For example, one port of the optical circulator 112 is connected to the light source 111, and the other port of the optical circulator 112 is connected to the light source 111. is connected to one end of the optical fiber assembly 20, so that the first light can only be output in one direction from the port connected to the optical fiber assembly 20. The optical splitter 113 can be connected to the third port of the optical circulator. In this way, the coherent optical signal returned from the passive pickup 31 is input from the port of the optical circulator connected to the optical fiber assembly 20 , then output from the port of the optical circulator connected to the optical splitter 113 , and transmitted to the optical splitter 113 .

The optical splitter 113 may be a Fiber Bragg Grating (FBG) or an Arrayed Waveguide Grating (AWG).

Among them, the spectrometer 113 is electrically connected to the photodetector array 115. The spectrometer 113 transmits the received coherent optical signal to the photodetector array 115. The photodetector array 115 receives the coherent optical signal and converts the coherent optical signal into electrical signals. The signal, the photodetector array 115 is connected to the signal processing module 114. The signal processing module 114 filters, amplifies and demodulates the electrical signal, and outputs a voice signal to realize the recovery of the sound at the position to be picked up. The number of split lights of the spectrometer 113 corresponds to the number of the photodetector arrays 115 .

It should be noted that in the embodiment of the present application, when the signal processing module 114 demodulates the electrical signal, the phase demodulation mechanism shown in Figure 17 can be used. As shown in Figure 17, single wavelength demodulation can be used. The operating point stabilization mechanism in Figure 17 maintains the best linearity and the highest demodulation sensitivity.

It should be noted that when the phase demodulation mechanism is used, the signal processing module 114 can also include an operating point stability control unit to monitor and adjust the operating wavelength of the laser 122 in real time, which can eliminate low-frequency phase jitter related to the environment and make the interference mechanism more stable. , thereby making the signal-to-noise ratio more stable; applying a small and fast disturbance (dither), detecting slope changes in real time, and the stable operating point is at the highest slope.

Alternatively, the three-wavelength demodulation mechanism shown in Figure 18 can also be used. When using the three-wavelength demodulation mechanism shown in Figure 3, refer to Figure 3 and Figure 19, and the algorithm selects the best linearity among the three operating points in real time. operating point to maintain demodulation stability.

It should be noted that the demodulation method of the signal processing module 114 includes but is not limited to a phase demodulation mechanism and a three-wavelength demodulation mechanism. For the demodulation principles of the phase demodulation mechanism and the three-wavelength demodulation mechanism, please refer to related technologies. This article In the application embodiment, the phase demodulation mechanism and the three-wavelength demodulation mechanism will not be described again.

In a possible implementation, the uplink pickup unit 11 also includes: an optical amplifier (not shown). The optical amplifier is arranged between the optical circulator 112 and the optical splitter 113. The optical amplifier is arranged between the optical circulator and the optical splitter unit. between them, in long-distance transmission scenarios, the received optical power can be increased. Among them, the optical amplifier may be an Erbium-doped Optical Fiber Amplifier (EDFA).

In a possible implementation, continuing to refer to FIG. 16 , when the number of passive communication terminals 30 is multiple, the optical fiber assembly 20 may include: a second optical fiber 22 and an optical splitter 23 . The optical splitter 23 One end of the second optical fiber 22 is connected to one end, the other end of the optical splitter 23 is connected to the passive communication terminal 30 , and the other end of the second optical fiber 22 is connected to the optical circulator 112 . In this way, the first light is transmitted to the optical splitter 23 through the second optical fiber 22, and the optical splitter 23 distributes the first light to each passive communication terminal 30 according to the number of channels.

The optical splitter 23 may be a wavelength division multiplexing device or a time division multiplexing device.

In a possible implementation, continuing to refer to FIG. 16 , in order to realize the playback of the voice signal output by the uplink sound pickup unit 11 , it also includes: a second sound-generating component 14 , the second sound-generating component 14 and a signal processing module 114 Electrical connection. The signal processed by the signal processing module 114 is output to the second sound-generating component 14, and the second sound-generating component 14 plays the output voice signal. The second sound-generating component 14 may be a speaker, or the second sound-generating component 14 may also be an earphone. In this way, the monitoring personnel can obtain the underground sound signal based on the second sound-generating component 14 .

In a possible implementation, in order to realize two-way communication in the passive communication system, as shown in Figure 20, it also includes: a downlink sound transmission unit 12 and an audio input unit 15. The audio input unit 15 and the downlink sound transmission unit 12 Connected, the audio input unit 15 is used to input audio signals to the downstream sound transmission unit 12, and the audio input unit 15 may be a microphone.

It should be noted that in the embodiment of the present application, when the downlink sound transmission unit 12 is included, since both the first light and the second light need to be transmitted to the passive communication terminal 30 through the second optical fiber 22, as shown in Figure 20, the optical fiber The component 20 may further include an optical multiplexer 21. One end of the optical multiplexer 21 is connected to both the uplink pickup unit 11 and the downlink sound transmission unit 12. The other end of the optical multiplexer 21 is connected to one end of the second optical fiber 22. Through the optical multiplexer 21, the third wave with different wavelengths can be The first light ray and the second light ray are combined onto the second optical fiber 22 for transmission.

The optical multiplexer 21 may be a wavelength division multiplexing device, or may be a time division multiplexing device.

In a possible implementation, as shown in Figure 20, the downlink sound transmission unit 12 includes: a modulation module 121 and a laser 122. The modulation unit is connected to the laser 122, and the laser 122 is connected to one end of the optical fiber assembly 20; the modulation unit is used to The audio signal input by the audio input unit 15 is modulated and loaded on the laser 122 ; the laser 122 is used to emit the second light loaded with the audio signal to the second sound-emitting component 14 of the passive phone terminal 30 . Wherein, the laser 122 may be a tunable laser 122.

In the embodiment of the present application, the downlink sound transmission process is specifically: the modulation module 121 receives the audio signal from the input end of the audio input unit 15, modulates the audio signal and loads it on the laser 122. The laser 122 emits a second light, and the second light is loaded with audio. signal, the second light is transmitted to the optical splitter 23 through the second optical fiber 22. The optical splitter 23 splits the light according to the wavelength and then transmits it to the first sound-generating component 32. The first sound-generating component 32 processes the first light and generates the audio signal. Restore to voice signal for output.

In the embodiment of the present application, the uplink sound pickup unit 11 and the downlink sound transmission unit 12 can be integrated into the central control device 10 as shown in Figure 21 . Of course, in some examples, the uplink sound pickup unit 11 and the downlink sound transmission unit 12 They can also be independent modules. The second sound-generating component 14, the audio input unit 15, and the power supply unit 13 can also be integrated together with the uplink sound pickup unit 11 and the downlink sound transmission unit 12 on the central control device 10. Of course, the second sound-generating component 14, the audio input unit 15 and the power supply unit 13 can also be independent devices. For example, an interface can be reserved on the central control device 10, and the second sound-generating component 14 and the audio input unit 15 can communicate with each other through the interface when necessary. The central control device 10 is connected to the reserved interface. Alternatively, the uplink sound pickup unit 11 is reserved with interfaces respectively corresponding to the second sound-generating component 14 and the power supply unit 13 , and the downlink sound transmission unit 12 is reserved with interfaces respectively corresponding to the audio input unit 15 and the power supply unit 13 .

In this embodiment of the present application, the modulation module 121 may be a device that combines a laser driver and a modulator. The modulation module 121 can use the internal modulation method as shown in Figure 22 or the external modulation method as shown in Figure 23 to change the light intensity of the laser 122 according to the electrical signal of the audio signal.

In the embodiment of the present application, the passive communication system can be networked through wavelength division multiplexing. According to the distribution needs of the passive communication terminals 30, single-level networking or multi-level networking can be used. For example, As shown in Figure 24, using a two-level network, multiple optical splitters 23 may be included, for example, optical splitters 23a and optical splitters 23b. The optical splitter 23a can perform first-stage light splitting, and the optical splitter 23b can perform second-stage light splitting. The passive communication terminals 30 connected to each optical splitter 23 can be set according to actual needs. For example, as shown in FIG. 25 , each optical splitter 23 can be connected to three passive communication terminals 30 .

Among them, in the embodiment of the present application, C-band WDM (wavelength division multiplexing) two-level networking is used when networking. See Figure 26. Taking 16 channels as an example, one path of light branched out by the optical splitter 23a is Corresponding to the six channels of channel 6 to channel 11, each channel can be connected to a passive pickup 31. Each channel corresponds to one wavelength of light. The other light branched out by the optical splitter 23a enters the optical splitter 23b. The light is split again. One path of light separated by the optical splitter 23b corresponds to the five channels of channel 1 to channel 5, and the other path of light corresponds to the five channels of channel 12 to channel 16.

Among them, Figure 27 is the output spectrum corresponding to the optical splitter 23 and 16 channels, L4 is the output spectrum line corresponding to the optical splitter 23a, L5 is the output spectrum line corresponding to the optical splitter 23b, L1, L2, L3 They are the output spectral lines corresponding to three of the wavelengths corresponding to the 16 channels, where L1 is the wavelength corresponding to channel 1 is 1525.5, L2 is the wavelength corresponding to channel 2 is 1528.5, and L3 is the wavelength corresponding to channel 3 is 1531.5. As can be seen from Figure 27, the optical splitter 23a can cover 6 wavelengths without interfering with other wavelength channels.

Among them, using traditional cascade optical splitting measures (for example, an optical splitter is connected to n channels respectively), in the case of n-channel optical splitting, the link loss is n*0.6dB. For a 16-channel network, the link loss is 9.6dB, it can only support 8km transmission.

In the embodiment of the present application, through C-band wavelength division multiplexing networking, for 16 channels, through two-level splitting, each optical splitter 23 is divided into 6 channels or 5 channels, so that one optical splitter connects 16 channels In terms of channels, the link loss is 3-3.6dB, which is 6.6-6dB lower than the traditional architecture. This improves wavelength utilization and reduces loss, which can increase the transmission distance by 12km and achieve a transmission distance that can support 20km.

Among them, when networking, the single-stage networking shown in Figure 28 can also be used, and all passive communication terminals 30 are connected to an optical splitter 23.

In a possible implementation, as shown in FIG. 29 , it also includes: a broadcast terminal 40 , the broadcast terminal 40 is arranged at a position to be picked up, and the broadcast terminal 40 is connected to the optical fiber assembly 20 . When the downlink sound transmission unit 12 transmits the audio signal to the broadcast terminal 40, the broadcast terminal 40 can broadcast the audio signal.

As shown in Figure 29, the broadcast terminal 40 includes: a light detector 41, an amplifier 42 and a speaker 43. The light detector 41 is connected to the output end of the optical fiber assembly 20, the light detector 41 is connected to the amplifier 42, and the speaker is connected to the amplifier 42. In this way, the photodetector 41 can convert the received second light into an electrical signal. The speaker 43 can be a low-power speaker, so that the light detector 41 can drive the speaker 43 to achieve broadcasting.

In some examples, when the speaker 43 is a high-power speaker, the light detector 41 may not be able to drive the speaker 43. For this reason, as shown in FIG. 30, the broadcast terminal 40 may also include: a battery 44. The battery 44 is connected to the light detector respectively. 41 is electrically connected to the speaker, and the battery 44 supplies power to the speaker and amplifier 42. In this way, the function of using high-power loudspeakers for broadcasting can be achieved.

As shown in Figure 30, it also includes: a power supply unit 13, which is connected to both the uplink sound pickup unit 11 and the downlink sound transmission unit 12. The power supply unit 13 provides power for the uplink sound pickup unit 11 and the downlink sound transmission unit 12 .

The embodiment of the present application also provides a passive call method, as shown in Figure 31. The method includes the following steps:

S101. Emit a first light to the passive communication terminal. The passive communication terminal reflects part of the first light to form a first reflected light. The passive communication terminal transmits part of the first light and then reflects it to form a second reflection. Light, and the second reflected light is loaded with a vibration signal generated by the vibration of the passive call terminal, and the first reflected light and the second reflected light interfere with each other to form a coherent light signal;

In the embodiment of this application, S101 may refer to the above-mentioned uplink sound pickup process, which will not be described again here.

S102. Receive the coherent optical signal returned from the passive communication terminal 30, and output a voice signal according to the vibration signal in the coherent optical signal.

The formation and demodulation of coherent optical signals may refer to the above description.

The passive calling method provided by the embodiment of the present application realizes the function of passive and long-distance sound pickup. When applied to coal mines or other special occasions, the sound underground in the coal mine can be picked up when the power is cut off, realizing the sound pickup function in coal mines. The long-distance and passive sound pickup function during a power outage can monitor and locate the pickup location in a timely manner, which is helpful for fault diagnosis or personnel rescue.

In the embodiment of the present application, as shown in Figure 32, the following step S103 is also included:

S103. Emit a second light to the passive call terminal 30, and the second light is loaded with an audio signal, so that the passive call terminal 30 makes a sound based on the audio signal.

The formation of the second light and the processing of the second light by the passive communication terminal 30 may refer to the above description. In addition, the audio signal can be generated based on the vibration signal in the coherent light signal, or the audio signal is combined with the coherent light signal. The vibration signal is not correlated.

Through step S103, in this way, the function of passive two-way communication is realized. When used in coal mines or other special occasions, two-way communication between the underground and above the mine can be achieved when the power is cut off, so that when an accident occurs, the sound pickup can be dealt with in a timely manner. Monitoring and positioning based on the location are helpful for fault diagnosis or personnel rescue.

It should be noted that in the embodiment of the present application, in Figure 32, step S103 is executed after step S102. However, in some examples, step S103 is not limited to being executed after step S102. For example, step S103 can also be executed after step S101. be executed before, or step S103 and step S102 may be executed at the same time.

The terms "first", "second", "third", "fourth", etc. (if present) in the description and claims of the embodiments of this application and the above-mentioned drawings are used to distinguish similar objects, and It is not necessary to describe a specific order or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances so that the embodiments of the application described herein can be practiced in sequences other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, e.g., a process, method, system, product, or apparatus that encompasses a series of steps or units and need not be limited to those explicitly listed. Those steps or elements may instead include other steps or elements not expressly listed or inherent to the process, method, product or apparatus.

The term "plurality" as used herein means two or more. The term "and/or" in this article is just an association relationship that describes related objects, indicating that three relationships can exist. For example, A and/or B can mean: A exists alone, A and B exist simultaneously, and they exist alone. B these three situations. In addition, the character "/" in this article generally indicates that the related objects before and after are an "or" relationship; in the formula, the character "/" indicates that the related objects before and after are a "division" relationship.

It can be understood that the various numerical numbers involved in the embodiments of the present application are only for convenience of description and are not used to limit the scope of the embodiments of the present application.

It can be understood that in the embodiments of the present application, the size of the sequence numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its functions and internal logic, and should not be used in the implementation of the present application. The implementation of the examples does not constitute any limitations.

Claims

A passive call terminal, characterized in that it includes: a passive pickup, which is set at a position to be picked up;

The passive pickup includes a beam shaping member and a diaphragm. The diaphragm is spaced apart from the beam shaping member. The beam shaping member is used to shape the first light received by the passive pickup and reflect part of the first light to form the first light. The reflected light and the partial light transmission of the first light form the transmitted light;

The diaphragm is used to vibrate under the action of sound waves at the position to be picked up to generate a vibration signal, and to reflect the transmitted light to form a second reflected light. The second reflected light is loaded with a vibration signal, and the first reflected light and the second reflected light Interfering with each other to form a coherent light signal.
The passive call terminal according to claim 1, characterized in that the passive pickup further includes: a ferrule, and the ferrule is provided with a first optical fiber;

One end of the ferrule and the beam shaping member are opposite to each other, and there is a gap between the beam shaping member and the ferrule. The gap is filled with filler. The filler bonds the beam shaping member and the ferrule, and the refractive index of the filler is consistent with the ferrule. Match the refractive index of the beam shaper.
The passive communication terminal according to claim 2, characterized in that the side of the beam shaping member facing the ferrule is an inclined surface, and the end of the first optical fiber and the ferrule facing the beam shaping member are inclined surfaces parallel to the inclined surface.
The passive communication terminal according to any one of claims 1 to 3, characterized in that,

The side of the diaphragm facing the beam shaping member has a first reflective surface;

One end of the beam shaping member facing the diaphragm has a second reflective surface;

There is a cavity between the second reflective surface of the beam shaping member and the first reflective surface of the diaphragm;

The second reflective surface is used to reflect part of the first light to form a first reflected light, and to transmit part of the first light to form a transmitted light;

The first reflective surface is used to reflect the transmitted light to form a second reflected light.
The passive communication terminal according to claim 4, characterized in that the side of the beam shaping member facing the diaphragm and the side of the diaphragm facing the cavity are two parallel planes;

And the distance between the side of the beam shaping member facing the diaphragm and the first reflective surface of the diaphragm is 400-1000 μm.
The passive call terminal according to any one of claims 1 to 5, characterized in that the passive pickup further includes:

Packaging fastener, the ferrule of the passive pickup is located in one end of the packaging fastener; the diaphragm of the passive pickup is located at the other end of the packaging fastener;

The beam shaper is located between the ferrule and diaphragm.
The passive communication terminal according to claim 6, wherein the packaging fastener includes: a first sleeve and a second sleeve located at one end of the first sleeve;

The ferrule and beam shaping member are both fixed in the second sleeve;

The diaphragm is located at the port at the other end of the first sleeve.
The passive communication terminal according to claim 7, characterized in that one of the first sleeve and the diaphragm of the passive pickup is provided with a through hole communicating with the cavity.
The passive communication terminal according to any one of claims 1 to 8, characterized in that the beam shaping member is a light collimating lens.
The passive communication terminal according to any one of claims 1 to 9, characterized in that the diaphragm of the passive pickup faces the light beam. One side of the shaping piece has a reflective film;

And the reflectivity of the reflective film is ≥95%.
The passive communication terminal according to any one of claims 1 to 10, characterized in that the beam shaping member is provided with an optical film on a side facing the diaphragm of the passive pickup;

The reflectivity of optical films ranges from 10-60%.
The passive communication terminal according to any one of claims 1 to 11, further comprising: a first sound-generating component, the first sound-generating component being used to produce sounds according to the received audio signal.
The passive communication terminal according to claim 12, characterized in that the first sound-generating component includes: a photovoltaic conversion unit and a sound-generating component, the input end of the photovoltaic conversion unit is used to receive the second light, and the second light is loaded with an audio signal, and the photovoltaic The output end of the conversion unit is connected to the sound-generating component;

The photovoltaic conversion unit is used to convert the received second light into an electrical signal, so that the sound-emitting member emits sound according to the audio signal.
The passive communication terminal according to claim 13, characterized in that the photovoltaic conversion unit includes a back electrode, an absorption layer, a window layer and a transparent electrode layer stacked from bottom to top.
The passive communication terminal according to claim 13 or 14, further comprising: a lens, the lens is arranged on the light incident side of the photovoltaic conversion unit.
A passive communication system, which is characterized by including:

N passive communication terminals according to any one of the above claims 1-15;

Uplink pickup unit, the uplink pickup unit is connected to N passive call terminals through optical fiber components;

The uplink pickup unit is used to emit the first light to the passive pickup, and receive the coherent optical signal returned from the passive pickup of the passive call terminal, so that the uplink pickup unit performs signal processing according to the received coherent optical signal to output voice signal;

N is an integer greater than or equal to 1.
The passive communication system according to claim 16, further comprising: a downlink sound transmission unit,

The downlink sound transmission unit is used to emit a second light to the passive communication terminal, and the second light is loaded with an audio signal, so that the first sound-emitting component of the passive communication terminal emits a sound according to the audio signal.
The passive communication system according to claim 17, further comprising: an audio input unit, the audio input unit is connected to the downlink sound transmission unit;

The audio input unit is used to input audio signals to the downstream sound transmission unit.
The passive communication system according to any one of claims 16 to 18, further comprising: a second sound-generating component, the second sound-generating component is electrically connected to the uplink pickup unit.
The passive communication system according to any one of claims 16 to 19, characterized in that the uplink sound pickup unit includes: a light source, an optical circulator, a light splitter, a light detector array and a signal processing module, and the light source is used to generate the first light;

One port of the optical circulator is connected to the light source, the other port of the optical circulator is used to connect to the optical fiber component, and the optical splitter is connected to the third port of the optical circulator;

The photodetector array is connected to the signal processing module, and the photodetector array is used to receive coherent optical signals and convert the coherent optical signals into electrical signals.
The passive communication system according to claim 20, characterized in that the uplink pickup unit further includes: an optical amplifier, and the optical amplifier is arranged between the optical circulator and the optical splitter.
The passive communication system according to claim 17 or 18, characterized in that the downlink sound transmission unit includes: modulation mode The block and the laser, the modulation unit is connected to the laser, and the laser is connected to one end of the optical fiber assembly;

The modulation unit is used to modulate the audio signal and load it on the laser;

The laser is used to emit the second light loaded with the audio signal to the passive communication terminal.
The passive communication system according to any one of claims 16 to 18, further comprising: a broadcast terminal, the broadcast terminal is located at a position to be picked up, and the broadcast terminal is connected to an optical fiber component.
The passive communication system according to claim 23, characterized in that the broadcast terminal includes: a light detector, an amplifier and a speaker;

The light detector is connected to the output end of the optical fiber component, and the light detector is connected to the amplifier;

The speakers are connected to the amplifier.
The passive communication system according to claim 24, characterized in that the broadcast terminal further includes a battery, and the battery is electrically connected to the light detector and the speaker respectively.
The passive communication system according to any one of claims 16 to 25, further comprising: an optical fiber component, the optical fiber component at least includes: a second optical fiber and an optical splitter;

One end of the optical splitter is connected to one end of the second optical fiber, and the other end of the optical splitter is connected to the passive communication terminal.
The passive communication system according to claim 26, characterized in that the optical fiber component further includes: an optical multiplexer, one end of the optical multiplexer is connected to both the uplink pickup unit and the downlink sound transmission unit of the passive communication system;

The other end of the optical combiner is connected to the other end of the second optical fiber.
The passive communication system according to claim 26 or 27, characterized in that the number of optical splitters is one or more;

When there is one optical splitter, one optical splitter is connected to N passive communication terminals;

When there are multiple optical splitters, the multiple optical splitters are arranged in series, and one optical splitter is connected to one or more terminals among the N passive communication terminals.
The passive communication system according to any one of claims 16 to 28, characterized in that the passive communication system further includes: a power supply unit, the power supply unit is connected to both the uplink sound pickup unit and the downlink sound transmission unit of the passive communication system.
A passive calling method, characterized in that the method includes:

The first light is emitted to the passive communication terminal, the passive communication terminal reflects part of the first light to form the first reflected light, and the passive communication terminal transmits part of the first light and then reflects it to form the second reflected light, And the second reflected light is loaded with a vibration signal generated by the vibration of the passive call terminal, and the first reflected light and the second reflected light interfere with each other to form a coherent light signal;

Receives the coherent optical signal returned from the passive call terminal, and outputs a voice signal based on the vibration signal in the coherent optical signal.
The passive calling method according to claim 30, further comprising:

A second light is emitted to the passive call terminal, and the second light is loaded with an audio signal, so that the passive call terminal makes a sound based on the audio signal.