Anti-resonance hollow-core fiber Raman amplification system

Abstract

The invention relates to an anti-resonance hollow-core optical fiber Raman amplification system, which is characterized in that a fiber core of an anti-resonance hollow-core optical fiber is filled with mixed gas of methane and hydrogen, and Raman amplification with the gain not lower than 8dB, the gain flatness not higher than 1.5 dB and the noise index not higher than 3dB is realized in a C-waveband communication window of 1522-1567nm by combining a pumping technology of 1040-1090nm. Wherein the design of the anti-resonance hollow-core optical fiber provides a medium for signal light transmission, and provides a working place for a gas stimulated Raman scattering effect; based on the gas control module, the proportion of methane and hydrogen filled in the anti-resonance hollow-core optical fiber and the gas pressure can be accurately regulated and controlled, and the hydrogen can inhibit methane decomposition, so that the gain gas in the anti-resonance hollow-core optical fiber is kept in a stable state. The technical problem that the gas gain efficiency and the transmission stability are difficult to synergistically improve is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communications, and in particular to an anti-resonance hollow-core optical fiber Raman amplification system. Background Art

[0002] In recent years, anti-resonant hollow-core fiber (AR-HCF) has caused a revolutionary breakthrough in the field of optical fiber communications due to its unique waveguide structure. Compared with traditional solid-core optical fiber, AR-HCF utilizes the anti-resonant light guiding mechanism, allowing light to propagate in the air medium with a relatively low refractive index, thereby significantly reducing the nonlinear effects, Rayleigh scattering loss and material absorption loss of the optical fiber. In addition, anti-resonant hollow-core fiber also has many other advantages, such as low latency, low dispersion, high transmission bandwidth and high damage threshold, and its cladding arrangement is simple and has a high degree of design freedom. These outstanding advantages make AR-HCF show disruptive potential in the fields of long-distance coherent optical communications and quantum key distribution.

[0003] However, to achieve ultra-long-distance antiresonant hollow-core fiber communication system applications, similar to traditional single-mode fiber communication systems, repeater amplification technology is required to compensate for transmission link losses. The long-distance systematic application of AR-HCF also requires an all-optical amplification module adapted to the hollow-core fiber structure. The all-optical amplification technology of traditional single-mode fiber communication systems primarily relies on the stimulated Raman scattering effect of rare-earth elements or solid gain materials doped in the fiber core. However, the light field of AR-HCF is confined to the hollow core, making it impossible to directly apply rare-earth doping technology, forcing researchers to turn their attention to gaseous gain media.

[0004] The theory of gas Raman amplification based on molecular vibrational / rotational energy level transitions was proposed by an MIT team as early as 2005. However, its practical application is limited by the physical contradiction between the strength of gas-light interaction and the robustness of the system. In the gas Raman amplification system for the C-band, it is specifically manifested as follows: (1) Insufficient stability of the gas gain medium. In the gas Raman amplification system for the C-band, methane gas has a relatively ideal gain coefficient and frequency shift characteristics. However, the cleavage of the CH bond of methane induced by high-power pump light not only produces carbon deposition and contaminates the hollow-core fiber, but also triggers local temperature gradients, causing mismatch of antiresonance conditions and introducing additional transmission loss in the fiber; (2) The trade-off between gain efficiency and transmission performance. To improve Raman gain, the gas concentration or fiber length needs to be increased, but this will aggravate transmission loss and mode mismatch; (3) Pump-signal coordinated optimization is difficult. Antiresonant hollow-core fiber Raman amplification systems must balance low coupling losses in both the pump and signal bands. This typically requires a large number of lens combinations, resulting in large space requirements and poor structural stability. Furthermore, current research on gas-filled AR-HCFs primarily focuses on gas lasers, with limited research on fiber-based Raman amplification systems.

[0005] CN119315363A discloses an ultra-wideband tunable fiber-optic communication light source based on gas stimulated Raman scattering, comprising a 1μm-band seed source, an electro-optic modulator, a signal generator, a fiber amplifier, a solid-core-hollow-core compact coupling device, a fiber end cap, a hollow-core fiber, a micro gas cavity, a lens, and a dichroic mirror. However, this invention focuses on gas Raman lasers and can only achieve a single wavelength conversion function. Furthermore, the decomposition of a single methane gain medium under strong pumping can cause carbon deposition pollution. Furthermore, it utilizes a spatial optical path coupling structure, relying entirely on mechanical adjustment and discrete spatial components. It maintains a fixed gas pressure solely through a pressure sensor and cannot respond to gain drift caused by changes in the external environment.

[0006] In summary, in order to realize ultra-long-distance antiresonant hollow-core fiber communication applications, it is urgent to develop an antiresonant hollow-core fiber Raman amplification system with stable system and controllable gain. Summary of the Invention

[0007] In response to the shortcomings of the existing technology, the purpose of the present invention is to provide an antiresonant hollow-core fiber Raman amplification system, which solves the technical problem of the difficulty in synergistically improving gas gain efficiency and transmission stability. It has important application prospects in the fields of hollow-core fiber long-distance coherent optical communication, ultra-low noise quantum key distribution and large-capacity data center interconnection.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] The present invention provides an antiresonant hollow-core fiber Raman amplification system, which includes a signal transmission module, a pump module, a coupling module, a gas control module, an antiresonant hollow-core fiber, and a signal receiving module. The signal light output by the signal transmission module and the pump light output by the pump module are combined by the coupling module and then injected into the antiresonant hollow-core fiber. The input end and the output end of the antiresonant hollow-core fiber are sealed in the gas control module. The gas control module is used to fill the antiresonant hollow-core fiber with a mixed gas of methane and hydrogen. The signal light and the pump light output by the antiresonant hollow-core fiber are respectively injected into the signal receiving module and the pump module through the coupling module.

[0010] The interior of the antiresonant hollow-core optical fiber is filled with a mixed gas of methane and hydrogen, providing a place for the pump light, the signal light and the mixed gas molecules to interact.

[0011] The present invention provides an antiresonant hollow-core fiber Raman amplification system. The present invention fills the core of the antiresonant hollow-core fiber with a mixture of methane and hydrogen, and combines pumping technology to achieve Raman amplification with a gain of no less than 8dB, a gain flatness of no more than 1.5dB, and a noise figure of no more than 3dB in the C-band communication window of 1522-1567nm. The transmission loss of the antiresonant hollow-core fiber is no more than 5dB / km, and the effective mode area is no less than 200μm 2 and the nonlinear coefficient is not higher than 1×10 -4 W -1 ·m -1 , providing a medium for signal light transmission and a workplace for the stimulated Raman scattering effect of gas; based on the gas control module of the present invention, the ratio of methane to hydrogen and the gas pressure filled in the antiresonant hollow-core fiber can be precisely controlled, and hydrogen can inhibit the decomposition of methane, ensuring that the gain gas in the antiresonant hollow-core fiber maintains a stable state. The present invention solves the technical problem of the difficulty in synergistically improving the gas gain efficiency and transmission stability in the antiresonant hollow-core fiber Raman amplification system, and has important application prospects in the fields of hollow-core fiber long-distance coherent optical communication, ultra-low noise quantum key distribution, and large-capacity data center interconnection.

[0012] Preferably, the antiresonant hollow-core fiber Raman amplification system has an operating band of 1522-1567 nm, a Raman gain ≥8 dB, a gain flatness ≤1.5 dB, a noise figure ≤3 dB, and a polarization-dependent gain ≤0.5 dB.

[0013] The operating band of the antiresonant hollow-core fiber Raman amplification system is 1522-1567 nm, and the wavelength can be 1522 nm, 1530 nm, 1545 nm, 1560 nm or 1567 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0014] The Raman gain of the antiresonant hollow-core fiber Raman amplification system is ≥8dB, for example, it can be 8dB, 9dB, 10dB, 11dB or 12dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0015] The gain flatness of the antiresonant hollow-core fiber Raman amplification system is ≤1.5dB, for example, it can be 1.5dB, 1.2dB, 1dB, 0.8dB or 0.6dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0016] The noise figure of the antiresonant hollow-core fiber Raman amplification system is ≤3dB, for example, it can be 3dB, 2.8dB, 2.5dB, 2dB or 1.5dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0017] The polarization-dependent gain of the antiresonant hollow-core fiber Raman amplification system is ≤0.5dB, for example, it can be 0.5dB, 0.4dB, 0.3dB, 0.2dB or 0.1dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0018] Preferably, the signal transmission module includes a signal light source, an IQ modulator and a first erbium-doped fiber amplifier connected in sequence, and the IQ modulator is connected to an arbitrary waveform generator.

[0019] Preferably, the output wavelength of the signal light source covers 1522-1567 nm, the line width is ≤1 MHz, and the output power is ≥10 mW.

[0020] The output wavelength of the signal light source covers 1522-1567 nm, for example, it can be 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] The line width of the signal light source is ≤1 MHz, for example, it can be 1 MHz, 0.8 MHz, 0.5 MHz, 0.3 MHz or 0.1 MHz, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0022] The output power of the signal light source is ≥10 mW, for example, it can be 10 mW, 12 mW, 15 mW, 18 mW or 20 mW, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0023] Preferably, the IQ modulator is based on a lithium niobate Mach-Zehnder structure, has a bandwidth ≥ 40 GHz, supports QPSK, 16-QAM and 64-QAM modulation formats, and has an insertion loss ≤ 3 dB.

[0024] The bandwidth of the IQ modulator is ≥40 GHz, for example, it can be 40 GHz, 42 GHz, 45 GHz, 48 GHz or 50 GHz, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0025] The insertion loss is ≤3dB, for example, it can be 3dB, 2.8dB, 2.5dB, 2dB or 1.5dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the sampling rate of the arbitrary waveform generator is ≥80 GHz, and the bandwidth is ≥32 GHz.

[0027] The sampling rate of the arbitrary waveform generator is ≥80 GHz, for example, it can be 80 GHz, 82 GHz, 85 GHz, 88 GHz or 90 GHz, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0028] The bandwidth of the arbitrary waveform generator is ≥32 GHz, for example, it can be 32 GHz, 35 GHz, 38 GHz, 40 GHz or 45 GHz, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0029] Preferably, the gain of the first erbium-doped fiber amplifier is ≥20 dB, the noise figure is ≤4.5 dB, the output saturation power is ≥23 dBm, and the operating band covers 1522-1567 nm.

[0030] The gain of the first erbium-doped fiber amplifier is ≥20 dB, for example, it can be 20 dB, 22 dB, 25 dB, 28 dB or 30 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] The noise figure of the first erbium-doped fiber amplifier is ≤4.5dB, for example, it can be 4.5dB, 4.2dB, 4dB, 3.5dB or 3dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0032] The output saturation power of the first erbium-doped fiber amplifier is ≥23dBm, for example, it can be 23dBm, 25dBm, 28dBm, 30dBm or 32dBm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0033] The operating wavelength band of the first erbium-doped fiber amplifier covers 1522-1567 nm, for example, it can be 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, the pump module includes a pump light source and a one-to-two coupler connected in sequence, the one-to-two coupler is connected to a main path and a monitoring path, the main path is provided with an optical circulator, and the monitoring path is provided with an optical power meter.

[0035] Preferably, the pump module includes a forward pump module, a reverse pump module and a bidirectional pump module.

[0036] Preferably, the output wavelength of the pump light source covers 1040-1090 nm, and the pump power is continuously adjustable and ≥1 W.

[0037] The output wavelength of the pump light source covers 1040-1090 nm, for example, it can be 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0038] The pump power of the pump light source is continuously adjustable and ≥1 W, for example, it can be 1 W, 1.2 W, 1.5 W, 1.8 W or 2 W, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0039] Preferably, the splitting ratio of the main path and the monitoring path of the one-to-two coupler is 90:10 to 99:1, the operating wavelength covers 1040-1090nm, the main path insertion loss is ≤1dB, the polarization-dependent loss is ≤0.2dB, and the power capacity is ≥1W.

[0040] The operating wavelength covers 1040-1090 nm, for example, it can be 1040 nm, 1050 nm, 1060 nm, 1075 nm or 1090 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] The main path insertion loss is ≤1 dB, for example, it can be 1 dB, 0.8 dB, 0.5 dB, 0.3 dB or 0.1 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0042] The polarization-dependent loss is ≤0.2 dB, for example, it can be 0.2 dB, 0.18 dB, 0.15 dB, 0.13 dB or 0.1 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0043] The power capacity is ≥1W, for example, it can be 1W, 1.2W, 1.5W, 1.8W or 2W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0044] Preferably, the operating wavelength of the optical circulator covers 1040-1090 nm, the three-port isolation is ≥40 dB, the insertion loss is ≤1.5 dB, and the power capacity is ≥10 W.

[0045] The operating wavelength of the optical circulator covers 1040-1090 nm, for example, it can be 1040 nm, 1050 nm, 1060 nm, 1080 nm or 1090 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0046] The three-port isolation is ≥40 dB, for example, it can be 40 dB, 45 dB, 50 dB, 55 dB or 60 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0047] The insertion loss is ≤1.5dB, for example, it can be 1.5dB, 1.2dB, 1dB, 0.8dB or 0.5dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0048] The power capacity is ≥10W, for example, it can be 10W, 12W, 15W, 18W or 20W, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0049] Preferably, the coupling module includes a wavelength division multiplexer, a six-dimensional coupling platform and an infrared achromatic lens connected in sequence.

[0050] Preferably, the wavelength division multiplexer supports bidirectional multiplexing and demultiplexing, and the operating wavelengths cover 1040-1090 nm and 1522-1567 nm. The isolation between the two operating bands is ≥40 dB, the insertion loss is ≤0.5 dB, and the polarization-dependent loss is ≤0.1 dB.

[0051] The operating wavelengths of the wavelength division multiplexer cover 1040-1090 nm and 1522-1567 nm. The wavelengths of 1040-1090 nm can be, for example, 1040 nm, 1050 nm, 1060 nm, 1080 nm or 1090 nm, but are not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. The wavelengths of 1522-1567 nm can be, for example, 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but are not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0052] The isolation between the two working bands is ≥40dB, for example, it can be 40dB, 42dB, 45dB, 48dB or 50dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0053] The insertion loss is ≤0.5dB, for example, it can be 0.5dB, 0.4dB, 0.3dB, 0.2dB or 0.1dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0054] The polarization-dependent loss is ≤ 0.1 dB, for example, it can be 0.1 dB, 0.08 dB, 0.05 dB, 0.03 dB or 0.01 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0055] Preferably, the focal length difference of the infrared achromatic lens in the wavelength range of 1040-1090 nm and 1522-1567 nm is ≤10 μm, the coating transmittance is ≥95%, and the numerical aperture range is 0.24-0.4.

[0056] The operating wavelengths of the infrared achromatic lens cover 1040-1090 nm and 1522-1567 nm. The wavelengths of 1040-1090 nm can be, for example, 1040 nm, 1050 nm, 1060 nm, 1080 nm or 1090 nm, but are not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. The wavelengths of 1522-1567 nm can be, for example, 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but are not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0057] The focal length difference within the wavelength ranges of 1040-1090 nm and 1522-1567 nm is ≤10 μm, for example, it can be 10 μm, 8 μm, 5 μm, 3 μm or 1 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0058] The coating transmittance is ≥95%, for example, it can be 95%, 96%, 97%, 98% or 99%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0059] The numerical aperture range is 0.24-0.4, for example, it can be 0.24, 0.3, 0.32, 0.35 or 0.4, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0060] Preferably, the six-dimensional coupling platform has a translation accuracy of ≤0.15 μm, a rotation accuracy of ≤0.05 mrad, supports an automatic calibration algorithm, has a coupling efficiency of ≥90%, and a mechanical stability of ≤0.01 dB / h.

[0061] The translation accuracy of the six-dimensional coupling platform is ≤0.15 μm, for example, it can be 0.15 μm, 0.12 μm, 0.1 μm, 0.08 μm or 0.05 μm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0062] The rotation accuracy of the six-dimensional coupling platform is ≤0.05 mrad, for example, it can be 0.05 mrad, 0.04 mrad, 0.03 mrad, 0.02 mrad or 0.01 mrad, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0063] The coupling efficiency of the six-dimensional coupling platform is ≥90%, for example, it can be 90%, 92%, 95%, 96% or 98%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0064] The mechanical stability of the six-dimensional coupling platform is ≤0.01dB / h, for example, it can be 0.01dB / h, 0.008dB / h, 0.005dB / h, 0.003dB / h or 0.001dB / h, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0065] Preferably, the gas control module includes an air chamber, the top of the air chamber is provided with an air inlet, and optical fiber insertion ports and light passages are respectively provided on both sides; the air inlet is connected to one port of the No. 1 three-way valve, the second port of the No. 1 three-way valve is connected to a vacuum pump, the third port of the No. 1 three-way valve is connected to one port of the No. 2 three-way valve, and the second port and third port of the No. 2 three-way valve are respectively connected to a methane gas tank and a hydrogen gas tank.

[0066] Preferably, the second port and the third port of the No. 2 three-way valve are respectively provided with mass flow meters for dynamically adjusting the content of methane and hydrogen in the mixed gas.

[0067] Preferably, the light port is coaxial with the infrared achromatic lens and the antiresonant hollow core fiber, and is used to inject the signal light and the pump light from the coupling module into the antiresonant hollow core fiber or from the antiresonant hollow core fiber into the coupling module.

[0068] Preferably, the wavelength of light passing through the light port covers 800-1700 nm, for example, it can be 800 nm, 1000 nm, 1200 nm, 1500 nm or 1700 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0069] Preferably, the optical fiber insertion port is connected to the anti-resonant hollow-core optical fiber, and is used to seal the input end and the output end of the anti-resonant hollow-core optical fiber in the air chamber.

[0070] Preferably, the gas control module further includes an air pressure sensor and a PID controller.

[0071] Preferably, the air pressure sensor has a measuring range of -0.1 to 20 MPa and an accuracy of ≤5 Pa.

[0072] The pressure sensor has a measuring range of -0.1 to 20 MPa, for example, -0.1 MPa, 1 MPa, 5 MPa, 10 MPa, 15 MPa or 20 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0073] The accuracy of the air pressure sensor is ≤5Pa, for example, it can be 5Pa, 4Pa, 3Pa, 2Pa or 1Pa, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0074] Preferably, the air chamber is made of rigid metal.

[0075] Preferably, the vacuum tightness of the gas control module is ≤2×10 -6 Pa, for example, can be 2×10 -6 Pa, 1.5×10 -6 Pa, 1×10 -6 Pa, 5×10 -7 Pa or 2×10 -7 Pa, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0076] Preferably, the mass ratio of methane to hydrogen in the mixed gas is 90:10 to 98:2, and the pressure of the mixed gas is ≤10 MPa.

[0077] The pressure of the mixed gas is ≤10 MPa, for example, it can be 10 MPa, 8 MPa, 5 MPa, 3 MPa or 1 MPa, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0078] Preferably, the antiresonant hollow-core optical fiber comprises a silica outer cladding, a silica antiresonant region, and an air core region, which are sequentially arranged from the outside to the inside.

[0079] Preferably, the silicon dioxide anti-resonance region includes at least four anti-resonance units with the same structure, each anti-resonance unit is composed of circular tubes at different levels, and the circular tubes at adjacent levels are in contact with each other.

[0080] Preferably, the number of the anti-resonance units is 4-8, for example, 4, 5, 6, 7 or 8.

[0081] Preferably, the number of levels of the anti-resonance unit is 1-5, for example, 1, 2, 3, 4 or 5.

[0082] Preferably, the thickness of the round tube is 0.3-2 μm, for example, 0.3 μm, 0.5 μm, 1 μm, 1.5 μm or 2 μm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0083] Preferably, the diameter of the air core region is ≤60 μm and not less than the maximum diameter of the circular tube, for example, it can be 60 μm, 55 μm, 50 μm, 45 μm or 40 μm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0084] Preferably, the length of the antiresonant hollow core fiber is ≥100 km, supports signal transmission in the wavelength range of 1040-1090 nm and 1522-1567 nm, has a fundamental mode transmission loss of ≤5 dB / km, and an effective mode area of ​​≥200 μm 2 , nonlinear coefficient ≤ 1×10 - 4 W -1 ·m -1 , high-order mode suppression ratio ≥100.

[0085] The length of the antiresonant hollow-core optical fiber is ≥100 km, for example, 100 km, 105 km, 110 km, 115 km or 120 km, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0086] The signal transmission wavelength range of the antiresonant hollow-core optical fiber supports 1040-1090 nm and 1522-1567 nm. 1040-1090 nm can be, for example, 1040 nm, 1050 nm, 1060 nm, 1070 nm, or 1090 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable. 1522-1567 nm can be, for example, 1522 nm, 1530 nm, 1545 nm, 1558 nm, or 1567 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0087] The fundamental mode transmission loss is ≤5dB / km, for example, it can be 5dB / km, 4dB / km, 3dB / km, 2dB / km or 1dB / km, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0088] The effective mode area is ≥ 200 μm 2 , for example, it can be 200μm 2 , 220μm 2 , 250μm 2 , 280μm 2 or 300 μm 2 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0089] The nonlinear coefficient is ≤1×10 -4 W -1 ·m -1 , for example, it can be 1×10 -4 W -1 ·m -1 , 0.8×10 -4 W -1 ·m -1 , 0.5×10 -4 W -1 ·m -1 , 0.3×10 -4 W -1 ·m -1 or ×10 -5 W -1 ·m -1 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0090] The high-order mode suppression ratio is ≥100, for example, it can be 100, 110, 120, 130 or 150, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0091] Preferably, the signal receiving module comprises a coherent detector, a tunable optical filter, a variable optical attenuator and a second erbium-doped fiber amplifier connected in sequence, and the coherent detector is connected to a local oscillator.

[0092] Preferably, the coherent detector has an operating wavelength covering 800-1700 nm, a bandwidth ≥40 GHz, a sensitivity ≤-30 dBm, a common mode rejection ratio ≥25 dB, and supports demodulation of QPSK, 16-QAM and 64-QAM modulation formats.

[0093] The operating wavelength of the coherent detector covers 800-1700 nm, for example, it can be 800 nm, 1000 nm, 1200 nm, 1400 nm or 1700 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0094] The bandwidth of the coherent detector is ≥40 GHz, for example, it can be 40 GHz, 50 GHz, 60 GHz, 70 GHz or 80 GHz, but is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0095] The sensitivity of the coherent detector is ≤-30dBm, for example, it can be -30dBm, -35dBm, -40dBm, -45dBm or -50dBm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0096] The common mode rejection ratio of the coherent detector is ≥25 dB, for example, it can be 25 dB, 26 dB, 28 dB, 30 dB or 32 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0097] Preferably, the wavelength tuning range of the local oscillator covers 1522-1567 nm, the line width is ≤1 MHz, and the power stability is ≤0.1 dB.

[0098] The wavelength tuning range of the local oscillator covers 1522-1567 nm, for example, it can be 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0099] The line width of the local oscillator is ≤1 MHz, for example, it can be 1 MHz, 0.8 MHz, 0.5 MHz, 0.3 MHz or 0.1 MHz, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0100] The power stability of the local oscillator is ≤0.1 dB, for example, it can be 0.1 dB, 0.08 dB, 0.05 dB, 0.03 dB or 0.01 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0101] Preferably, the wavelength tuning range of the tunable optical filter covers 1522-1567 nm, the bandwidth range is 0.1-2 nm, and the insertion loss is ≤1.5 dB.

[0102] The wavelength tuning range of the tunable optical filter covers 1522-1567 nm, for example, it can be 1522 nm, 1530 nm, 1545 nm, 1558 nm or 1567 nm, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0103] The bandwidth of the tunable optical filter is in the range of 0.1-2 nm, for example, 0.1 nm, 0.5 nm, 1 nm, 1.5 nm or 2 nm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0104] The insertion loss of the tunable optical filter is ≤1.5dB, for example, it can be 1.5dB, 1.2dB, 1dB, 0.8dB or 0.5dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0105] Preferably, the variable optical attenuator has an attenuation range of 0-30 dB, a resolution of ≤0.1 dB, and supports real-time power feedback adjustment.

[0106] The attenuation range of the variable optical attenuator is 0-30 dB, for example, 0 dB, 5 dB, 10 dB, 20 dB or 30 dB, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0107] The resolution of the variable optical attenuator is ≤0.1 dB, for example, it can be 0.1 dB, 0.08 dB, 0.05 dB, 0.03 dB or 0.01 dB, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0108] Compared with the prior art, the present invention has the following beneficial effects:

[0109] (1) Significantly improved gas gain medium stability: By introducing a mixed gas system of methane and hydrogen, combined with closed-loop regulation of a high-precision gas control module, a dynamic balance of gas composition is achieved. Hydrogen, as an inhibitor, effectively delays the decomposition of methane molecules under strong pumping, preventing carbon deposition from contaminating the fiber core. At the same time, the coordinated operation of the vacuum pump and mass flow meter ensures the long-term stability of the mixed gas ratio, significantly improving the operating life and reliability of the system.

[0110] (2) Coordinated optimization of pump light and signal light: Based on the hollow-core fiber design with a multi-layer anti-resonant structure, the transmission loss of pump light and signal light, as well as the degree of mode mismatch between the two, are effectively reduced by precisely controlling the core size of the anti-resonant hollow-core fiber and the geometric parameters of the anti-resonant unit. In addition, the innovative combination of a customized infrared achromatic lens and a six-dimensional coupling platform is used to achieve coaxial precision coupling of pump light and signal light over a wide spectral range. This design significantly reduces the insertion loss and polarization sensitivity of the traditional multi-lens system by eliminating the focal length difference between beams of different wavelengths. At the same time, the integrated solution of all-fiber devices simplifies the optical path structure, providing a feasible basis for large-scale deployment of the system.

[0111] (3) Dynamically reconfigurable amplification system: The system supports flexible switching between forward, reverse, and bidirectional pump configurations. Combined with the wavelength combination strategy of the tunable pump light source, the gain distribution can be optimized in real time based on the actual transmission distance and signal power requirements. This dynamic adjustment capability enables the system to adapt to complex optical network environments and achieve balanced gain spectrum flatness over long-distance transmission.

[0112] (4) Multi-dimensional noise suppression capability: The low nonlinear characteristics of hollow-core fiber and the optimization of the molecular energy levels of the mixed gas effectively suppress spontaneous emission noise and cross-phase modulation effects. Combined with the constant pressure maintenance function of the gas control module, the Raman gain drift caused by pressure fluctuations is reduced, thus achieving the unity of ultra-low noise figure and high signal fidelity at the system level.

[0113] (5) Comprehensively improved system robustness: The modular coupling unit and hermetic packaging structure effectively isolate external environmental interference. The PID control algorithm and the closed-loop feedback mechanism of the air pressure sensor achieve high-precision dynamic compensation of gas parameters. This self-stabilizing feature enables the system to maintain stable amplification performance under complex operating conditions such as temperature changes and mechanical vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Figure 1 Schematic diagram of the structure of the anti-resonant hollow-core fiber Raman amplification system provided by the present invention;

[0115] Figure 2 It is a structural diagram of the signal transmission module provided by the present invention;

[0116] Figure 3 Schematic diagram of the structure of the pump module provided by the present invention;

[0117] Figure 4 It is a structural diagram of the coupling module provided by the present invention;

[0118] Figure 5 It is a structural diagram of the gas control module provided by the present invention;

[0119] Figure 6 Schematic diagram of the structure of the antiresonant hollow-core optical fiber provided by the present invention;

[0120] Figure 7 It is a structural diagram of the signal receiving module provided by the present invention;

[0121] Figure 8 This is a spectrum diagram of the Raman gain and noise index of the antiresonant hollow-core fiber Raman amplification system provided in Example 1 of the present invention.

[0122] Among them: 1, signal transmission module; 1-1, signal light source; 1-2, IQ modulator; 1-3, arbitrary waveform generator; 1-4, first erbium-doped fiber amplifier; 2, pump module; 2-1, pump light source; 2-2, one-to-two coupler; 2-3, optical power meter; 2-4, optical circulator; 3, coupling module; 3-1, wavelength division multiplexer; 3-2, infrared achromatic lens; 3-3, six-dimensional coupling platform; 4, gas control module; 4-1, gas chamber; 4-2, vacuum pump; 4-3, methane gas tank; 4-4, Hydrogen tank; 4-5, three-way valve No. 1; 4-6, three-way valve No. 2; 4-7, air inlet; 4-8, light port; 4-9, optical fiber insertion port; 5, antiresonant hollow-core optical fiber; 5-1, silica outer cladding; 5-2, silica antiresonance region; 5-3, air core region; 5-4, antiresonance unit; 5-5, circular tube; 6, signal receiving module; 6-1, coherent detector; 6-2, local oscillator; 6-3, tunable optical filter; 6-4, variable optical attenuator; 6-5, second erbium-doped fiber amplifier. DETAILED DESCRIPTION

[0123] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0124] The present invention provides an anti-resonant hollow-core fiber Raman amplification system, the structural diagram of which is shown in FIG. Figure 1 As shown, the amplification working band of the antiresonant hollow-core fiber Raman amplification system is 1522-1567nm, the Raman gain is ≥8dB, the gain flatness is ≤1.5dB, the noise figure is ≤3dB, and the polarization-dependent gain is ≤0.5dB; the antiresonant hollow-core fiber Raman amplification system includes a signal transmitting module 1, a pump module 2, a coupling module 3, a gas control module 4, an antiresonant hollow-core fiber 5 and a signal receiving module 6; the signal light output by the signal transmitting module 1 and the pump light output by the pump module 2 are combined by the coupling module 3 and injected into the antiresonant hollow-core fiber 5, the input end and the output end of the antiresonant hollow-core fiber 5 are sealed in the gas control module 4, and the gas control module 4 is used to fill the antiresonant hollow-core fiber 5 with a mixed gas of methane and hydrogen, and the signal light and the pump light output by the antiresonant hollow-core fiber 5 are respectively injected into the signal receiving module 6 and the pump module 2 through the coupling module 3.

[0125] The structural diagram of the signal transmitting module 1 is as follows Figure 2As shown, it is used to output signal light of the required wavelength in the C band; the signal transmission module 1 includes a signal light source 1-1, an IQ modulator 1-2 and a first erbium-doped fiber amplifier 1-4 connected in sequence, and the IQ modulator 1-2 is connected to an arbitrary waveform generator 1-3; the output wavelength of the signal light source 1-1 covers 1522-1567nm, the line width ≤1MHz, and the output power ≥10mW. The narrow line width and high power of the signal light source 1-1 can ensure the stability of the signal light, reduce phase noise, and facilitate coherent detection and long-distance transmission of the signal light; the IQ modulator 1-2 is based on a lithium niobate Mach-Zehnder structure, has a bandwidth ≥40GHz, supports QPSK, 16-QAM and 64-QAM modulation formats, has an insertion loss ≤3dB, and the IQ The modulator 1-2 doubles the spectral efficiency by introducing a high-order modulation format for the signal. The arbitrary waveform generator 1-3 has a sampling rate ≥80 GHz and a bandwidth ≥32 GHz, and can be used to generate a pre-distorted waveform through programming, thereby compensating for signal distortion caused by the nonlinear effects of the mixed gas during transmission, allowing the signal to be transmitted with fidelity in the hundred-kilometer-level antiresonant hollow-core fiber 5. The first erbium-doped fiber amplifier 1-4 has a gain ≥20 dB, a noise figure ≤4.5 dB, an output saturation power ≥23 dBm, and an operating band covering 1522-1567 nm. Its pre-amplification function ensures that the signal light power exceeds the coupling threshold of the antiresonant hollow-core fiber 5, and at the same time suppresses ASE noise accumulation through an optimized gain equalization algorithm, providing a high-quality input signal for subsequent gas Raman amplification.

[0126] The structural diagram of the pump module 2 is as follows: Figure 3 As shown, it is used to output pump light in the 1μm band required for stimulated Raman scattering of methane; the pump module 2 includes a pump light source 2-1 and a one-to-two coupler 2-2 connected in sequence, the one-to-two coupler 2-2 is connected to a main path and a monitoring path, the main path is provided with an optical circulator 2-4, and the monitoring path is provided with an optical power meter 2-3; the pump module 2 includes a forward pump module, a reverse pump module and a bidirectional pump module; the output wavelength of the pump light source 2-1 covers 1040-1090nm, the pump power is continuously adjustable and ≥1W, and the output wavelength of the pump light source 2-1 matches the Raman frequency shift of the methane molecule (2914cm -1), Raman amplification of 1522-1567nm signal light is achieved through wavelength / power joint tuning; the splitting ratio of the main path and the monitoring path of the one-to-two coupler 2-2 is 90:10 to 99:1, the operating wavelength covers 1040-1090nm, the main path insertion loss is ≤1dB, the polarization-dependent loss is ≤0.2dB, and the power capacity is ≥1W. The pump light output by the monitoring path is monitored in real time by the optical power meter 2-3, and the pump light output by the main path is input into the coupling module 3 via the optical circulator 2-4; the operating wavelength of the optical circulator 2-4 covers 1040-1090nm, the three-port isolation is ≥40dB, the insertion loss is ≤1.5dB, and the power capacity is ≥10W. In a bidirectional pumping configuration, it can achieve path isolation of forward / reverse pump light to prevent high-power return light from damaging the pump light source 2-1.

[0127] The structural diagram of the coupling module 3 is as follows Figure 4 As shown, it is used to combine the signal light and the pump light and couple them into the antiresonant hollow core fiber 5; the coupling module 3 includes a wavelength division multiplexer 3-1, a six-dimensional coupling platform 3-3 and an infrared achromatic lens 3-2 connected in sequence; the wavelength division multiplexer 3-1 supports bidirectional multiplexing and demultiplexing, and the operating wavelength covers 1040-1090nm and 1522-1567nm, the isolation of the two working bands is ≥40dB, the insertion loss is ≤0.5dB, and the polarization dependent loss is ≤0. The infrared achromatic lens 3-2 has a focal length difference of ≤10μm in the wavelength ranges of 1040-1090nm and 1522-1567nm, a coating transmittance of ≥95%, and a numerical aperture range of 0.24-0.4. The six-dimensional coupling platform 3-3 has a translational accuracy of ≤0.15μm, a rotational accuracy of ≤0.05mrad, supports an automatic calibration algorithm, a coupling efficiency of ≥90%, and a mechanical stability of ≤0.01dB / h. The innovative combination of a customized infrared achromatic lens 3-2 and a six-dimensional coupling platform 3-3 achieves coaxial, precise coupling of pump light and signal light across a wide spectral range. By eliminating the focal length differences between beams of different wavelengths, this design significantly reduces the insertion loss and polarization sensitivity of traditional multi-lens systems, simplifies the optical path structure, and provides a feasible foundation for large-scale deployment of the system.

[0128] The structural diagram of the gas control module 4 is as follows Figure 5As shown, a mixed gas of methane and hydrogen is filled in the antiresonant hollow core optical fiber 5; the gas control module 4 includes an air chamber 4-1 made of rigid metal, the top of the air chamber 4-1 is provided with an air inlet 4-7, and optical fiber insertion ports 4-9 and light through ports 4-8 are provided on both sides; the air inlet 4-7 is connected to one port of the No. 1 three-way valve 4-5, the second port of the No. 1 three-way valve 4-5 is connected to a vacuum pump 4-2 for pre-extracting residual gas in the air chamber 4-1 and the antiresonant hollow core optical fiber 5, the third port of the No. 1 three-way valve 4-5 is connected to one port of the No. 2 three-way valve 4-6, and the second port of the No. 2 three-way valve 4-6 is connected to the The second port and the third port are respectively connected to the methane gas tank 4-3 and the hydrogen gas tank 4-4; the second port and the third port of the No. 2 three-way valve 4-6 are respectively provided with mass flow meters for dynamically adjusting the content of methane and hydrogen in the mixed gas; the light port 4-8 is coaxial with the infrared achromatic lens 3-2 and the antiresonant hollow-core optical fiber 5, and is used to inject the signal light and the pump light from the coupling module 3 into the antiresonant hollow-core optical fiber 5 or from the antiresonant hollow-core optical fiber 5 into the coupling module 3; the optical fiber insertion port 4-9 is connected to the antiresonant hollow-core optical fiber 5, and is used to seal the input end and the output end of the antiresonant hollow-core optical fiber 5 in the gas chamber 4-1.

[0129] The wavelength of light passing through the light ports 4-8 covers 800-1700nm; the gas control module 4 also includes a pressure sensor and a PID controller; the pressure sensor has a range of -0.1 to 20MPa and an accuracy of ≤5Pa; the vacuum sealing degree of the gas control module 4 is ≤2×10 -6 Pa; the mass ratio of methane to hydrogen in the mixed gas is 90:10 to 98:2, and the pressure of the mixed gas is ≤10MPa.

[0130] The structural diagram of the antiresonant hollow core optical fiber 5 is as follows: Figure 6 As shown, it is used to transmit signal light, and its interior is filled with a mixed gas of methane and hydrogen, providing a place for the interaction between pump light, signal light and mixed gas molecules; the antiresonant hollow-core optical fiber 5 includes a silica outer cladding 5-1, a silica antiresonance region 5-2 and an air core region 5-3 arranged in sequence from the outside to the inside; the silica antiresonance region 5-2 includes 4-8 antiresonance units 5-4 with the same structure, each antiresonance unit 5-4 is composed of 1-5 levels of circular tubes 5-5, the circular tubes 5-5 of adjacent levels are in contact, and the thickness of the circular tubes 5-5 is 0.3-2μm; the diameter of the air core region 5-3 is ≤60μm and is not less than the maximum diameter of the circular tube 5-5; the length of the antiresonant hollow-core optical fiber 5 is ≥100km, supporting signal transmission in the wavelength range of 1040-1090nm and 1522-1567nm, with a fundamental mode transmission loss ≤5dB / km and an effective mode area ≥200μm 2 , nonlinear coefficient ≤ 1×10 -4 W-1 ·m -1 , high-order mode suppression ratio ≥100.

[0131] The structural diagram of the signal receiving module 6 is as follows Figure 7 As shown, it is used to receive signal light, convert the optical signal into an electrical signal and recover the original data therefrom; the signal receiving module 6 includes a coherent detector 6-1, a tunable optical filter 6-3, a variable optical attenuator 6-4 and a second erbium-doped fiber amplifier 6-5 connected in sequence, and the coherent detector 6-1 is connected to a local oscillator 6-2; the operating wavelength of the coherent detector 6-1 covers 800-1700nm, the bandwidth ≥40GHz, the sensitivity ≤-30dBm, the common mode rejection ratio ≥25dB, and supports QPS K, 16-QAM and 64-QAM modulation formats demodulation; the wavelength tuning range of the local oscillator 6-2 covers 1522-1567nm, the linewidth ≤1MHz, and the power stability ≤0.1dB; the wavelength tuning range of the tunable optical filter 6-3 covers 1522-1567nm, the bandwidth range is 0.1-2nm, and the insertion loss ≤1.5dB; the attenuation range of the variable optical attenuator 6-4 is 0-30dB, the resolution ≤0.1dB, and supports real-time power feedback adjustment.

[0132] Example 1

[0133] This embodiment provides an antiresonant hollow-core fiber Raman amplification system, including a signal transmitting module 1 , a pumping module 2 , a coupling module 3 , a gas control module 4 , an antiresonant hollow-core fiber 5 and a signal receiving module 6 .

[0134] In this embodiment, the signal transmission module 1 is used to output signal light of the required wavelength in the C-band. The signal light source 1-1 is a Keysight N7711A tunable laser, with an output wavelength continuously adjustable in the range of 1522-1567nm, a linewidth of 0.8MHz, an output power of 15mW, and a narrow linewidth C-band seed light. The phase noise is less than -120dBc / Hz, ensuring transmission coherence at the 100-kilometer level. The IQ modulator 1-2 is an iXblue MX1600-LN-40 lithium niobate Mach-Zehnder modulator with a bandwidth of 45GHz, supporting the 16-QAM modulation format, and an insertion loss of 2.5dB. Loading the 16-QAM modulation format on the channel doubles the spectrum efficiency. The arbitrary waveform generator 1-3 is a Tektronix AWG70002A with a sampling rate of 92GSa / s and a bandwidth of 36GHz. It is used to generate pre-distorted waveforms to compensate for signal distortion caused by gas nonlinearity. The first erbium-doped fiber amplifier 1-4 is a Keopsys KPS-C-23-BO has a gain of 25dB, a noise figure of 4dB, an output saturation power of 25dBm, and an operating band of 1522-1567nm. It is used to increase the signal power to 10dBm, breaking the hollow-core fiber coupling threshold.

[0135] In this embodiment, pump module 2 is used to output pump light in the 1μm band required for stimulated Raman scattering of methane. Pump light source 2-1 is an IPG Photonics YLR-10-LP fiber laser with an output wavelength of 1064nm and a continuously adjustable output power of 1-10W. One-to-two coupler 2-2 is a Thorlabs TW1064R2F1A broadband fiber coupler with a 90:10 split ratio between the main and monitoring channels. Its effective operating wavelength range is 964-1164nm, with a main channel insertion loss of 0.9dB, a polarization-dependent loss of 0.15dB, and a power capacity of 5W. Optical power meter 2-3 is an EXFO PPM-300 optical power monitoring module. Optical circulator 2-4 is an OZ Optics 3P-1064-SS high-power circulator, operating in the 1040-1090nm wavelength range, with 45dB three-port isolation, 1.2dB insertion loss, and a power capacity of 15W.

[0136] In this embodiment, coupling module 3 is used to combine signal light and pump light and couple them into antiresonant hollow-core fiber 5. Wavelength division multiplexer 3-1 is a customized 1064 / 1550 nm filter-type wavelength division multiplexer from Mingchuang Optoelectronics. Its operating wavelengths cover 1040-1090 nm and 1522-1567 nm, with 40 dB isolation, 0.5 dB insertion loss, and 0.1 dB polarization-dependent loss between the two operating bands. The infrared achromatic lens 3-2 is a customized product with an 8 μm focal length difference in the 1040-1090 nm and 1522-1567 nm wavelength ranges, a coating transmittance of 95%, and a numerical aperture range of 0.3. The six-dimensional coupling platform 3-3 is a Newport AG-UL6-R automated six-dimensional alignment platform with a translational accuracy of 0.12 μm, a rotational accuracy of 0.03 mrad, support for an automatic calibration algorithm, a coupling efficiency of 92.3%, and mechanical stability of ≤0.008 dB / h.

[0137] In this embodiment, the gas control module 4 is used to fill the antiresonant hollow-core fiber 5 with a mixture of methane and hydrogen. The gas control module 4 is a customized module, wherein the gas chamber 4-1 is made of stainless steel, the top of the gas chamber is provided with an air inlet 4-7, and the two sides are provided with a fiber insertion port 4-9 and a light port 4-8, and the light wavelength of the light port 4-8 covers 800-1700nm; the model of the first three-way valve 4-5 and the model of the second three-way valve 4-6 are both Swagelok SS-43GXS6; the second port of the first three-way valve 4-5 is connected to the vacuum pump 4-2, model Pfeiffer HiPace 300, with an ultimate vacuum degree of 2×10 -6 Pa; the second port and the third port of the No. 2 three-way valve 4-6 are respectively connected to the methane gas tank 4-3 and the hydrogen gas tank 4-4, and each is equipped with a mass flow meter; the gas control module 4 also includes a pressure sensor and a PID controller, the models are MKS 626B and Omega CNi3243, respectively, with a range of -0.1 to 20 MPa and an accuracy of 2 Pa; the gas control module 4 ultimately achieves a mass ratio of methane to hydrogen in the antiresonant hollow-core optical fiber 5 of 95:5, and the pressure of the mixed gas is ≤0.4 MPa.

[0138] In this embodiment, the antiresonant hollow-core optical fiber 5 is used to transmit signal light, and its interior is filled with a mixture of methane and hydrogen, providing a place for the pump light, signal light and the mixed gas molecules to interact. The antiresonant hollow-core optical fiber 5 includes a silica outer cladding 5-1, a silica antiresonance region 5-2 and an air core region 5-3, which are arranged in sequence from the outside to the inside; the outer diameter and inner diameter of the silica outer cladding are 142μm and 82.5μm respectively; the silica antiresonance region 5-2 includes five antiresonance units 5-4 with the same structure, each antiresonance unit 5-4 is composed of three levels of circular tubes 5-5, and the circular tubes 5-5 of adjacent levels are in contact, and the outer diameter and thickness of the outer circular tube 5-5 are 28μm respectively. and 0.45 μm, the outer diameter and thickness of the middle circular tube 5-5 are 21 μm and 0.45 μm respectively, and the outer diameter and thickness of the inner circular tube 5-5 are 9.5 μm and 0.37 μm respectively; the diameter of the air core region 5-3 is 26.5 μm; the length of the antiresonant hollow core optical fiber 5 is 100 km, supporting signal transmission in the wavelength range of 1040-1090 nm and 1522-1567 nm, the fundamental mode transmission loss is not higher than 4 dB / km, and the effective mode area is ≥325.8 μm 2 , nonlinear coefficient ≤ 3×10 -10 W -1 ·m -1 , the high-order mode suppression ratio is 156.

[0139] In this embodiment, the signal receiving module 6 is used to receive signal light, convert the optical signal into an electrical signal, and recover the original data. The coherent detector 6-1 has an operating wavelength range of 800-1700nm, a bandwidth of 40GHz, a sensitivity of -40dBm, a common-mode rejection ratio of 30dB, and supports demodulation of the 64-QAM modulation format. The local oscillator 6-2 has a wavelength tuning range of 1522-1567nm, a linewidth of 0.5MHz, and a power stability of 0.1dB. The tunable optical filter 6-3 has a wavelength tuning range of 1522-1567nm, a bandwidth of 2nm, and an insertion loss of 1.5dB. The variable optical attenuator 6-4 has an attenuation range of 0-30dB, a resolution of 0.1dB, and supports real-time power feedback adjustment.

[0140] The operating band of the antiresonant hollow-core fiber Raman amplification system in this embodiment is 1522-1567 nm, the Raman gain is not less than 8.25 dB, the gain flatness is 0.52 dB, the noise figure is not higher than 2.92 dB, and the polarization-dependent gain is not higher than 0.45 dB. The spectra of the Raman gain and noise figure are shown in FIG. Figure 8 shown.

[0141] In summary, the antiresonant hollow-core fiber Raman amplification system provided by the present invention can significantly improve the stability of the gas gain medium: by introducing a mixed gas system of methane and hydrogen, combined with the closed-loop control of a high-precision gas control module, a dynamic balance of gas components is achieved. Hydrogen, as an inhibitor, effectively delays the decomposition process of methane molecules under strong pumping, avoiding the contamination of the optical fiber core by carbon deposition. At the same time, through the coordinated work of the vacuum pump and the mass flow meter, the long-term stability of the mixed gas ratio is guaranteed, significantly improving the operating life and reliability of the system. The pump light and the signal light are synergistically optimized: based on the hollow-core fiber design of the multi-layer antiresonant structure, the core size of the antiresonant hollow-core fiber and the geometric parameters of the antiresonant unit are precisely controlled to effectively reduce the transmission loss of the pump light and the signal light, as well as the degree of mode mismatch between the two. In addition, the innovative combination of a customized infrared achromatic lens and a six-dimensional coupling platform is used to achieve coaxial precision coupling of the pump light and the signal light over a wide spectral range. This design significantly reduces the insertion loss and polarization sensitivity of traditional multi-lens systems by eliminating focal length differences between beams of different wavelengths. The integrated all-fiber design simplifies the optical path, paving the way for large-scale deployment. It features a dynamically reconfigurable amplification system: The system supports flexible switching between forward, reverse, and bidirectional pumping configurations. Combined with a tunable pump light source wavelength combination strategy, the gain profile can be optimized in real time based on the actual transmission distance and signal power requirements. This dynamic adjustment capability enables the system to adapt to complex optical network environments and achieve balanced gain spectrum flatness over long-distance transmission. It also exhibits multi-dimensional noise suppression: The low nonlinearity of the hollow-core fiber and the optimized molecular energy levels of the gas mixture effectively suppress spontaneous emission noise and cross-phase modulation effects. Combined with the constant pressure maintenance function of the gas control module, it reduces Raman gain drift caused by pressure fluctuations, achieving a combination of ultra-low noise figure and high signal fidelity at the system level. System robustness is comprehensively enhanced: The modular coupling unit and hermetic packaging structure effectively isolate external environmental interference. The PID control algorithm and closed-loop feedback mechanism of the pressure sensor enable high-precision dynamic compensation of gas parameters. This self-stabilizing feature enables the system to maintain stable amplification performance under complex working conditions such as temperature changes or mechanical vibrations.

[0142] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. An anti-resonant hollow-core fiber Raman amplification system, characterized in that: The antiresonant hollow-core fiber Raman amplification system includes a signal transmitting module, a pump module, a coupling module, a gas control module, an antiresonant hollow-core fiber, and a signal receiving module; the signal light output by the signal transmitting module and the pump light output by the pump module are combined by the coupling module and injected into the antiresonant hollow-core fiber, the input end and the output end of the antiresonant hollow-core fiber are sealed in the gas control module, and the gas control module is used to fill the antiresonant hollow-core fiber with a mixed gas of methane and hydrogen, and the signal light and the pump light output by the antiresonant hollow-core fiber are respectively injected into the signal receiving module and the pump module through the coupling module; The interior of the antiresonant hollow-core optical fiber is filled with a mixed gas of methane and hydrogen, providing a place for the pump light, the signal light and the mixed gas molecules to interact.

2. The antiresonant hollow-core fiber Raman amplification system according to claim 1, characterized in that: The antiresonant hollow-core fiber Raman amplification system has an operating band of 1522-1567 nm, a Raman gain of 8 dB or more, a gain flatness of 1.5 dB or less, a noise figure of 3 dB or less, and a polarization-dependent gain of 0.5 dB or less.

3. The antiresonant hollow-core fiber Raman amplification system according to claim 1 or 2, characterized in that: The signal transmission module includes a signal light source, an IQ modulator and a first erbium-doped fiber amplifier connected in sequence, and the IQ modulator is connected to an arbitrary waveform generator; Preferably, the output wavelength of the signal light source covers 1522-1567nm, the line width is ≤1MHz, and the output power is ≥10mW; Preferably, the IQ modulator is based on a lithium niobate Mach-Zehnder structure, has a bandwidth ≥ 40 GHz, supports QPSK, 16-QAM and 64-QAM modulation formats, and has an insertion loss ≤ 3 dB; Preferably, the sampling rate of the arbitrary waveform generator is ≥80 GHz and the bandwidth is ≥32 GHz; Preferably, the gain of the first erbium-doped fiber amplifier is ≥20 dB, the noise figure is ≤4.5 dB, the output saturation power is ≥23 dBm, and the operating band covers 1522-1567 nm.

4. The antiresonant hollow-core fiber Raman amplification system according to any one of claims 1 to 3, characterized in that: The pump module includes a pump light source and a one-to-two coupler connected in sequence, the one-to-two coupler is connected to a main path and a monitoring path, the main path is provided with an optical circulator, and the monitoring path is provided with an optical power meter; Preferably, the pump module includes a forward pump module, a reverse pump module and a bidirectional pump module.

5. The antiresonant hollow-core fiber Raman amplification system according to claim 4, characterized in that: The output wavelength of the pump light source covers 1040-1090nm, and the pump power is continuously adjustable and ≥1W; Preferably, the splitting ratio of the main path and the monitoring path of the one-to-two coupler is 90:10 to 99:1, the operating wavelength covers 1040-1090nm, the main path insertion loss is ≤1dB, the polarization-dependent loss is ≤0.2dB, and the power capacity is ≥1W; Preferably, the operating wavelength of the optical circulator covers 1040-1090 nm, the three-port isolation is ≥40 dB, the insertion loss is ≤1.5 dB, and the power capacity is ≥10 W.

6. The antiresonant hollow-core fiber Raman amplification system according to any one of claims 1 to 5, characterized in that: The coupling module includes a wavelength division multiplexer, a six-dimensional coupling platform and an infrared achromatic lens connected in sequence; Preferably, the wavelength division multiplexer supports bidirectional multiplexing and demultiplexing, and the operating wavelengths cover 1040-1090 nm and 1522-1567 nm, the isolation between the two working bands is ≥40 dB, the insertion loss is ≤0.5 dB, and the polarization-dependent loss is ≤0.1 dB; Preferably, the infrared achromatic lens has a focal length difference of ≤10 μm in the wavelength range of 1040-1090 nm and 1522-1567 nm, a coating transmittance of ≥95%, and a numerical aperture range of 0.24-0.4; Preferably, the six-dimensional coupling platform has a translation accuracy of ≤0.15 μm, a rotation accuracy of ≤0.05 mrad, supports an automatic calibration algorithm, has a coupling efficiency of ≥90%, and a mechanical stability of ≤0.01 dB / h.

7. The antiresonant hollow-core fiber Raman amplification system according to claim 6, characterized in that: The gas control module includes an air chamber, the top of which is provided with an air inlet, and two sides of which are provided with an optical fiber insertion port and a light passage port; the air inlet is connected to one port of a No. 1 three-way valve, the second port of the No. 1 three-way valve is connected to a vacuum pump, the third port of the No. 1 three-way valve is connected to one port of a No. 2 three-way valve, and the second port and the third port of the No. 2 three-way valve are connected to a methane gas tank and a hydrogen gas tank, respectively; Preferably, the second port and the third port of the No. 2 three-way valve are respectively provided with mass flow meters for dynamically adjusting the content of methane and hydrogen in the mixed gas; Preferably, the light port is coaxial with the infrared achromatic lens and the antiresonant hollow-core fiber, and is used to inject the signal light and the pump light from the coupling module into the antiresonant hollow-core fiber or from the antiresonant hollow-core fiber into the coupling module; Preferably, the light transmission wavelength of the light port covers 800-1700nm; Preferably, the optical fiber insertion port is connected to the anti-resonant hollow-core optical fiber, and is used to seal the input end and the output end of the anti-resonant hollow-core optical fiber in the air chamber.

8. The antiresonant hollow-core fiber Raman amplification system according to claim 7, characterized in that: The gas control module also includes an air pressure sensor and a PID controller; Preferably, the air pressure sensor has a measuring range of -0.1 to 20 MPa and an accuracy of ≤5 Pa; Preferably, the air chamber is made of rigid metal; Preferably, the vacuum tightness of the gas control module is ≤2×10 -6 Pa; Preferably, the mass ratio of methane to hydrogen in the mixed gas is 90:10 to 98:2, and the pressure of the mixed gas is ≤10 MPa.

9. The antiresonant hollow-core fiber Raman amplification system according to any one of claims 1 to 8, characterized in that: The antiresonant hollow core optical fiber comprises a silica outer cladding, a silica antiresonant region and an air core region arranged in sequence from the outside to the inside; Preferably, the silicon dioxide anti-resonance region comprises at least four anti-resonance units of the same structure, each anti-resonance unit is composed of circular tubes of different levels, and the circular tubes of adjacent levels are in contact; Preferably, the number of the anti-resonance units is 4-8; Preferably, the number of levels of the anti-resonance unit is 1-5; Preferably, the thickness of the round tube is 0.3-2 μm; Preferably, the diameter of the air core region is ≤60 μm and not less than the maximum diameter of the circular tube; Preferably, the length of the antiresonant hollow core fiber is ≥100 km, supports signal transmission in the wavelength range of 1040-1090 nm and 1522-1567 nm, has a fundamental mode transmission loss of ≤5 dB / km, and an effective mode area of ​​≥200 μm 2 , nonlinear coefficient ≤ 1×10 -4 W -1 ·m -1 , high-order mode suppression ratio ≥100.

10. The antiresonant hollow-core fiber Raman amplification system according to any one of claims 1 to 9, characterized in that: The signal receiving module includes a coherent detector, a tunable optical filter, a variable optical attenuator and a second erbium-doped fiber amplifier connected in sequence, and the coherent detector is connected to a local oscillator; Preferably, the coherent detector has an operating wavelength range of 800-1700 nm, a bandwidth ≥40 GHz, a sensitivity ≤-30 dBm, a common mode rejection ratio ≥25 dB, and supports demodulation of QPSK, 16-QAM, and 64-QAM modulation formats; Preferably, the wavelength tuning range of the local oscillator covers 1522-1567 nm, the line width is ≤1 MHz, and the power stability is ≤0.1 dB; Preferably, the wavelength tuning range of the tunable optical filter covers 1522-1567 nm, the bandwidth range is 0.1-2 nm, and the insertion loss is ≤1.5 dB; Preferably, the variable optical attenuator has an attenuation range of 0-30 dB, a resolution of ≤0.1 dB, and supports real-time power feedback adjustment.

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