An anti-interference testing device for fiber optic pickup

Abstract

The application discloses an anti-interference testing device for an optical fiber pickup, which comprises a laser source, a coupler, a pickup probe, an input optical fiber sensing line and an output optical fiber sensing line, the laser source is connected with the coupler through the input optical fiber sensing line, the output optical fiber sensing line is also connected with the coupler, and the pickup probe is connected with the coupler; the coupler is connected with the pickup probe, the pickup probe is used for converting a sound signal into an optical signal and transmitting the optical signal to the coupler; and the input optical fiber sensing line and the output optical fiber sensing line are both formed by alternately butting two different doped A optical fibers and B optical fibers. The optical fiber is made of two sections of different materials, and the temperature drift phenomenon of the resonant wavelength can be inhibited due to the different doping.

Description

Technical Field

[0001] This invention relates to the field of microphone technology, and in particular to an anti-interference testing device for fiber optic microphones. Background Technology

[0002] Fiber optic microphones integrate sensing and transmission, and are a new type of sound information acquisition and sensing device that uses optical fiber as both the sensing element and the transmission medium. Their structure is simple, consisting of a laser source, coupler, microphone probe, and fiber optic sensing circuitry. Fiber optic microphones can pick up and reproduce sound signals; they are passive microphones. The pickup section uses ordinary optical fiber, without any electrical conversion, and has advantages such as electromagnetic interference resistance, corrosion resistance, explosion-proof properties, and intrinsic safety. They can be used for monitoring the operational status of GIL (Gas Infrared Transmission Line) equipment.

[0003] Fiber optic microphones are based on two technologies: those based on optical intensity modulation and those based on interference. Currently, the most mature fiber optic microphone technologies internationally are based on optical intensity modulation, such as those from Optoacoustics in Israel and MicroOptics Technologies in the United States. Their performance has now met the requirements for practical use.

[0004] Experiments have shown that any physical quantity that can alter the effective refractive index or grating period of a fiber optic grating can change its center wavelength. Strain (or stress) and temperature are the physical quantities that most directly and significantly change the grating wavelength. When the grating is subjected to external strain (or stress), the grating period changes, and the elasto-optic effect causes a change in the grating's effective refractive index. When the grating is affected by external temperature, thermal expansion causes a change in the grating period, and the thermosensitive effect causes a change in the grating's effective refractive index. Summary of the Invention

[0005] To address this, the present invention provides an anti-interference testing device for an optical fiber microphone, comprising a laser source, a coupler, a pickup probe, an input optical fiber sensing line, and an output optical fiber sensing line. The laser source is connected to the coupler via the input optical fiber sensing line, and the output optical fiber sensing line is also connected to the coupler. The pickup probe is connected to the coupler. The laser source is used to emit a carrier beam, and the coupler is used to superimpose and couple the optical signals converted from sound signals. The sound is then output as an optical signal through the output fiber optic sensing line for sound pickup. The coupler connects to the sound pickup probe, which converts the sound signal into an optical signal and transmits the optical signal to the coupler. Both the input and output fiber optic sensing lines are formed by alternately connecting two A-fibers and B-fibers with different doping. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The material is placed in a platinum crucible, and a layer of ammonium bifluoride is covered on the mixed fluoride. The crucible is then covered, and the mixture is heated in an argon atmosphere at a temperature of 900–950°C for at least 2 hours. The molten material is then removed, poured into a mold, and air-cooled to 230±10°C. This temperature is then maintained for 5–6 hours. After cooling to room temperature in the furnace, the surface of the cooled material is polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2, and NaF are fully mixed. The raw material mixture is obtained by mixing evenly. The raw material mixture is placed in a crucible and placed in a muffle furnace. The temperature is raised to 1300±10℃ in an argon protective atmosphere and held for 40-50 minutes. After the holding time is completed, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened and the glass sample is taken out and placed in an annealing furnace at a temperature range of 350±10℃ for more than 24 hours. Then the power of the annealing furnace is turned off and the glass sample is cooled to room temperature with the furnace. The surface is polished to obtain glassy B-fiber.

[0006] Furthermore, the molar ratio of the mixture of silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form the mixed fluoride is silver fluoride: indium trifluoride: praseodymium fluoride: gallium fluoride: yttrium fluoride: barium fluoride: zinc fluoride: lithium fluoride: strontium fluoride = 10~12:24~30:2~5:10~20:1~4:15~20:15~20:2~7:6~10.

[0007] Furthermore, the ammonium bifluoride coating thickness is 3-5 mm.

[0008] Furthermore, the molar ratio of B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 5~8:2~3:66~70:6~10:1~2:10~12:6~10.

[0009] Furthermore, the A optical fiber and the B optical fiber are fixed together by pressing with epoxy resin.

[0010] The beneficial effect of this invention is that the resonant wavelength of a fiber optic grating drifts with temperature, which is highly detrimental to practical applications. Therefore, it is necessary to find a way to suppress the resonant wavelength drift of the fiber optic grating. This invention uses two sections of optical fiber made of different materials. Due to the different doping, the temperature drift phenomenon of the resonant wavelength can be suppressed. Experiments show that when the temperature decreases, the resonant wavelength of the fiber optic grating drifts towards longer wavelengths, which cancels out the drift of the resonant wavelength of the fiber optic grating towards shorter wavelengths caused by the temperature decrease. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of the device described in this invention. Detailed Implementation

[0012] The present invention will be further described below with reference to the embodiments.

[0013] Example 1

[0014] An anti-interference testing device for an optical fiber microphone includes a laser source 1, a coupler 2, a microphone probe 3, an input optical fiber sensing line 4, and an output optical fiber sensing line 5. The laser source 1 is connected to the coupler 2 via the input optical fiber sensing line 4, and the output optical fiber sensing line 5 is also connected to the coupler 2. The microphone probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output optical fiber sensing line 5. The microphone probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. The input optical fiber sensing line 4 and the output optical fiber sensing line 5 are both formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride is silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 10:24:2:10:1:15:15:2:6. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and heated in an argon atmosphere at 900°C for 2 hours. The molten metal was then removed, poured into a mold, and air-cooled to 230±10°C. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2, and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is 5:2:66:6:1:10:6. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0015] Example 2

[0016] An anti-interference testing device for an optical fiber microphone includes a laser source 1, a coupler 2, a microphone probe 3, an input optical fiber sensing line 4, and an output optical fiber sensing line 5. The laser source 1 is connected to the coupler 2 via the input optical fiber sensing line 4, and the output optical fiber sensing line 5 is also connected to the coupler 2. The microphone probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output optical fiber sensing line 5. The microphone probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. The input optical fiber sensing line 4 and the output optical fiber sensing line 5 are both formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride is silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:26:3:12:2:17:16:4:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and argon atmosphere was placed inside the furnace. The furnace was then heated to 910℃ for 2 hours. The molten liquid was then removed, poured into a mold, and air-cooled to 230±10℃. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 6:2:67:7:1:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0017] Example 3

[0018] An anti-interference testing device for an optical fiber microphone includes a laser source 1, a coupler 2, a microphone probe 3, an input optical fiber sensing line 4, and an output optical fiber sensing line 5. The laser source 1 is connected to the coupler 2 via the input optical fiber sensing line 4, and the output optical fiber sensing line 5 is also connected to the coupler 2. The microphone probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output optical fiber sensing line 5. The microphone probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. The input optical fiber sensing line 4 and the output optical fiber sensing line 5 are both formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:15:3:18:17:5:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and heated in an argon atmosphere at 930°C for 2 hours. The molten metal was then removed, poured into a mold, and air-cooled to 230±10°C. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2, and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 7:3:68:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0019] Example 4

[0020] An anti-interference testing device for an optical fiber microphone includes a laser source 1, a coupler 2, a microphone probe 3, an input optical fiber sensing line 4, and an output optical fiber sensing line 5. The laser source 1 is connected to the coupler 2 via the input optical fiber sensing line 4, and the output optical fiber sensing line 5 is also connected to the coupler 2. The microphone probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output optical fiber sensing line 5. The microphone probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. The input optical fiber sensing line 4 and the output optical fiber sensing line 5 are both formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:18:3:19:19:6:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and heated in an argon atmosphere at 940°C for 2 hours. The molten metal was then removed, poured into a mold, and air-cooled to 230±10°C. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2, and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is 7:3:69:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0021] Example 5

[0022] An anti-interference testing device for an optical fiber microphone includes a laser source 1, a coupler 2, a microphone probe 3, an input optical fiber sensing line 4, and an output optical fiber sensing line 5. The laser source 1 is connected to the coupler 2 via the input optical fiber sensing line 4, and the output optical fiber sensing line 5 is also connected to the coupler 2. The microphone probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output optical fiber sensing line 5. The microphone probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. The input optical fiber sensing line 4 and the output optical fiber sensing line 5 are both formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride is silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 12:30:5:20:4:20:20:7:10. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. Then, the crucible is covered, and an argon atmosphere is placed inside to melt and hold at a temperature of 900-950℃ for 2 hours. The melt is then removed, poured into a mold, and air-cooled to 230±10℃. This temperature is then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material is polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 8:3:70:10:2:12:10. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0023] Comparative Example 1

[0024] A comparative device includes a laser source 1, a coupler 2, a microphone 3, an input fiber optic sensing line 4, and an output fiber optic sensing line 5. The laser source 1 is connected to the coupler 2 via the input fiber optic sensing line 4, and the output fiber optic sensing line 5 is also connected to the coupler 2. The microphone 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output fiber optic sensing line 5. The microphone 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. Both the input fiber optic sensing line 4 and the output fiber optic sensing line 5 are made of A-fiber. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:15:3:18:17:5:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. Then, the crucible is covered and argon atmosphere is placed in the temperature range of 930℃ for 2 hours to melt and hold. Then, the melt is taken out and poured into the mold, air-cooled to 230±10℃, and then held at this temperature for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material is polished to obtain glassy A-fiber.

[0025] Comparative Example 2

[0026] A comparative device includes a laser source 1, a coupler 2, a microphone 3, an input fiber optic sensing line 4, and an output fiber optic sensing line 5. The laser source 1 is connected to the coupler 2 via the input fiber optic sensing line 4, and the output fiber optic sensing line 5 is also connected to the coupler 2. The microphone 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output fiber optic sensing line 5. The microphone 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. Both the input fiber optic sensing line 4 and the output fiber optic sensing line 5 are made of B-fiber. The method for preparing the B-fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 7:3:68:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0027] Comparative Example 3

[0028] A comparative device includes a laser source 1, a coupler 2, a pickup probe 3, an input fiber optic sensing line 4, and an output fiber optic sensing line 5. The laser source 1 is connected to the coupler 2 via the input fiber optic sensing line 4, and the output fiber optic sensing line 5 is also connected to the coupler 2. The pickup probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output fiber optic sensing line 5. The pickup probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. Both the input fiber optic sensing line 4 and the output fiber optic sensing line 5 are formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2 cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:15:3:18:17:5:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. Then, the crucible is covered, and an argon atmosphere is placed inside to melt and hold at a temperature of 930℃ for 2 hours. The melt is then removed, poured into a mold, and air-cooled to 230±10℃. This temperature is then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material is polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials TeO2, Na2O, CeO2, BaF2 and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of TeO2:Na2O:CeO2:BaF2:NaF = 68:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0029] Comparative Example 4

[0030] A comparative device includes a laser source 1, a coupler 2, a pickup probe 3, an input fiber optic sensing line 4, and an output fiber optic sensing line 5. The laser source 1 is connected to the coupler 2 via the input fiber optic sensing line 4, and the output fiber optic sensing line 5 is also connected to the coupler 2. The pickup probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output fiber optic sensing line 5. The pickup probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. Both the input fiber optic sensing line 4 and the output fiber optic sensing line 5 are formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2 cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:15:3:18:17:5:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and heated in an argon atmosphere at 930°C for 2 hours. The molten metal was then removed, poured into a mold, and air-cooled to 230±10°C. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials B2O3, TeO2, Na2O, CeO2, BaF2, and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of B2O3:TeO2:Na2O:CeO2:BaF2:NaF is 7:68:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0031] Comparative Example 5

[0032] A comparative device includes a laser source 1, a coupler 2, a pickup probe 3, an input fiber optic sensing line 4, and an output fiber optic sensing line 5. The laser source 1 is connected to the coupler 2 via the input fiber optic sensing line 4, and the output fiber optic sensing line 5 is also connected to the coupler 2. The pickup probe 3 is connected to the coupler 2. The laser source 1 emits a carrier beam. The coupler 2 is used to superimpose and couple an optical signal converted from a sound signal, and then outputs it as an optical signal for sound pickup via the output fiber optic sensing line 5. The pickup probe 3 is connected to the coupler 2 and is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler 2. Both the input fiber optic sensing line 4 and the output fiber optic sensing line 5 are formed by alternately splicing two A-fibers 6 and B-fibers 7 with different doping. Each segment of A-fiber and B-fiber is 2 cm long and is fixed by pressing with epoxy resin. The A-fiber is prepared by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form a mixed fluoride. The molar ratio of the mixed fluoride to the silver fluoride:indium trifluoride:praseodymium fluoride:gallium fluoride:yttrium fluoride:barium fluoride:zinc fluoride:lithium fluoride:strontium fluoride = 11:28:4:15:3:18:17:5:8. The mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is coated on the mixed fluoride with a coating thickness of 5 mm. The crucible was then covered and heated in an argon atmosphere at 930°C for 2 hours. The molten metal was then removed, poured into a mold, and air-cooled to 230±10°C. This temperature was then maintained for 5 hours. After cooling to room temperature in the furnace, the surface of the cooled material was polished to obtain the glassy A-fiber. The preparation method of the B-fiber is as follows: the raw materials GeO2, TeO2, Na2O, CeO2, BaF2, and NaF are thoroughly mixed to obtain a raw material mixture. The molar ratio of GeO2:TeO2:Na2O:CeO2:BaF2:NaF is 3:68:8:2:11:8. The raw material mixture is placed in a crucible and then placed in a muffle furnace. Under an argon protective atmosphere, the temperature is raised to 1300±10℃ and held for 40 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. The mold is then air-cooled to room temperature. The mold is opened, the glass sample is taken out, and placed in an annealing furnace at a temperature of 350±10℃ for 24 hours. Then the power to the annealing furnace is turned off, and the glass sample is cooled to room temperature with the furnace. The surface is then polished to obtain glassy B-fiber.

[0033] Example 6

[0034] The devices obtained in the above embodiments and comparative examples were tested for the lowest operating temperature (the temperature drop range was 5°C, that is, if the device can work normally at a certain temperature, the temperature was reduced by 5°C and the test was repeated until the device could not work normally. The lowest temperature at which it could work normally was recorded as the lowest operating temperature of the device). The results are shown in Table 1.

[0035] Table 1

[0036] Example 1 -30 Example 2 -30 Example 3 -35 Example 4 -35 Example 5 -30 Comparative Example 1 -10 Comparative Example 2 -15 Comparative Example 3 -15 Comparative Example 4 -20 Comparative Example 5 -20

[0037] As shown in Table 1, by using two sections of optical fiber made of different materials, this invention can broaden the operating temperature range of the optical fiber pickup, reduce the minimum operating temperature, and expand the application fields of the optical fiber pickup.

[0038] The technical solutions provided by the present invention have been described in detail above. For those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An anti-interference testing device for an optical fiber microphone, comprising a laser source, a coupler, a microphone probe, an input optical fiber sensing line, and an output optical fiber sensing line, wherein the laser source is connected to the coupler via the input optical fiber sensing line, the output optical fiber sensing line is also connected to the coupler, and the microphone probe is connected to the coupler; the laser source is used to emit a carrier beam, the laser source is connected to the coupler via the input optical fiber sensing line, the coupler is used to superimpose and couple an optical signal converted from a sound signal, and then output an optical signal for microphone pickup via the output optical fiber sensing line; the coupler is connected to the microphone probe, the microphone probe is used to convert the sound signal into an optical signal and transmit the optical signal to the coupler; characterized in that... Both the input and output fiber optic sensing circuits are formed by alternating connections of two A-fibers and B-fibers with different doping. The A-fiber is prepared as follows: a mixed fluoride is formed by mixing silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride. This mixed fluoride is placed in a platinum crucible, and a layer of ammonium bifluoride is placed on top. The crucible is then sealed, and the mixture is heated in an argon atmosphere at a temperature of 900–950°C for at least 2 hours. The molten material is then removed, poured into a mold, and air-cooled to 230±10°C. This temperature is maintained for 5–6 hours, and the mixture is then cooled to room temperature in the furnace. The surface of the cooled material is polished to obtain the glassy A-fiber. Optical fiber; the preparation method of the B optical fiber is as follows: the raw materials B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF are thoroughly mixed to obtain a raw material mixture. The raw material mixture is placed in a crucible and placed in a muffle furnace. The temperature is raised to 1300±10℃ in an argon protective atmosphere and held for 40-50 minutes. After the holding period, the glass melt is quickly poured into a mold that has been preheated to 300±10℃ and held. Then the mold is air-cooled to room temperature. The mold is opened and the glass sample is taken out and placed in an annealing furnace at a temperature range of 350±10℃ for more than 24 hours. Then the power of the annealing furnace is turned off and the glass sample is cooled to room temperature with the furnace. The surface is polished to obtain the glassy B optical fiber.

2. The fiber optic microphone anti-interference testing device according to claim 1, characterized in that, The molar ratio of the mixture of silver fluoride, indium trifluoride, praseodymium fluoride, gallium fluoride, yttrium fluoride, barium fluoride, zinc fluoride, lithium fluoride, and strontium fluoride to form the mixed fluoride is silver fluoride: indium trifluoride: praseodymium fluoride: gallium fluoride: yttrium fluoride: barium fluoride: zinc fluoride: lithium fluoride: strontium fluoride = 10~12:24~30:2~5:10~20:1~4:15~20:15~20:2~7:6~10.

3. The fiber optic microphone anti-interference testing device according to claim 1, characterized in that, The ammonium bifluoride coating thickness is 3-5 mm.

4. The fiber optic microphone anti-interference testing device according to claim 1, characterized in that, The molar ratio of B2O3, GeO2, TeO2, Na2O, CeO2, BaF2 and NaF is B2O3:GeO2:TeO2:Na2O:CeO2:BaF2:NaF = 5~8:2~3:66~70:6~10:1~2:10~12:6~10.

5. The fiber optic microphone anti-interference testing device according to claim 1, characterized in that, The A and B optical fibers are fixed together by pressing with epoxy resin.

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