阅读说明：本技术 一种可调谐等离子体光子晶体光纤装置 (Tunable plasma photonic crystal fiber device ) 是由 吴淑群 刘敏格 卞伟杰 顾亚楠 张潮海 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种可调谐等离子体光子晶体光纤装置,包括光子晶体光纤、高压脉冲电源、保护电阻、高压电极、绝缘片、地电极、入射布鲁斯特窗和出射布鲁斯特窗。红外激光经入射布鲁斯特窗进入光子晶体光纤并从出射布鲁斯特窗射出,高压脉冲电源向高压电极施加脉冲电压,通过介质阻挡多孔放电的形式在充满惰性工作气体的空心孔内获得低温等离子体,实现填充等离子体的光子晶体光纤；通过改变高压电源脉冲参数、惰性工作气体的气压或者电极间距,能够调节等离子体的特征物理参数和气体温度,对光子晶体光纤的红外带隙特征进行宽范围调谐。本发明具备调谐连续、可重构、调谐频段宽、响应速度快的优点,在光学通信方面具有广阔的工业应用前景。(The invention discloses a tunable plasma photonic crystal fiber device which comprises a photonic crystal fiber, a high-voltage pulse power supply, a protective resistor, a high-voltage electrode, an insulating sheet, a ground electrode, an incident Brewster window and an emergent Brewster window. Infrared laser enters the photonic crystal fiber through the incident Brewster window and is emitted from the emergent Brewster window, the high-voltage pulse power supply applies pulse voltage to the high-voltage electrode, and low-temperature plasma is obtained in the hollow hole filled with inert working gas in a dielectric barrier porous discharge mode, so that the photonic crystal fiber filled with the plasma is realized; by changing the pulse parameters of the high-voltage power supply and the air pressure or the electrode distance of the inert working gas, the characteristic physical parameters and the air temperature of the plasma can be adjusted, and the infrared band gap characteristic of the photonic crystal fiber can be tuned in a wide range. The invention has the advantages of continuous tuning, reconfigurability, wide tuning frequency band and high response speed, and has wide industrial application prospect in the aspect of optical communication.)

1. A tunable plasmonic crystal fiber device, characterized by: the high-voltage pulse laser comprises a photonic crystal fiber, a high-voltage pulse power supply, a protective resistor, a high-voltage electrode, an insulating sheet, a ground electrode, an incident Brewster window and an emergent Brewster window; the photonic crystal fiber is internally provided with a periodically arranged hollow hole array, each hollow hole penetrates through two ends of the photonic crystal fiber, and inert working gas is filled in each hollow hole; the incident Brewster window and the emergent Brewster window allow infrared light to penetrate through, are respectively arranged at two ends of the photonic crystal fiber, and seal the space between the two Brewster windows and the two ends of the photonic crystal fiber; the high-voltage electrode, the insulating sheet and the ground electrode are respectively in close contact with the surface of the photonic crystal fiber, the insulating sheet is arranged between the high-voltage electrode and the ground electrode, the output end of the high-voltage pulse power supply is electrically connected with the high-voltage electrode through a protective resistor, and the grounding end of the high-voltage pulse power supply is electrically connected with the ground electrode; infrared laser enters the photonic crystal fiber through the incident Brewster window and is emitted from the emergent Brewster window, the high-voltage pulse power supply applies pulse voltage to the high-voltage electrode, and low-temperature plasma is obtained in the hollow hole filled with inert working gas in a dielectric barrier porous discharge mode, so that the photonic crystal fiber filled with the plasma is realized; by changing the pulse parameters of the high-voltage power supply, the gas pressure of the inert working gas or the distance between the high-voltage electrode and the ground electrode, the characteristic physical parameters and the gas temperature of the plasma can be adjusted, and the infrared band gap characteristic of the photonic crystal fiber can be tuned in a wide range.

2. The tunable plasmonic crystal fiber device of claim 1, wherein: the hollow hole array is distributed in a circular, annular, rectangular or pentagonal shape, the number of the hollow holes is 3-120, and the inner diameter of each hollow hole is 3-45 mu m; the fiber core of the photonic crystal fiber is a single core or a double core, the diameter of the fiber core is 10-60 mu m, and the material of the fiber core is quartz, pure silicon or air holes; the diameter of the cross section of the photonic crystal fiber is less than 1mm, and the length of the photonic crystal fiber is 80-200 mm.

3. The tunable plasmonic crystal fiber device of claim 1, wherein: the two Brewster windows respectively have a Brewster angle with the vertical section of the photonic crystal fiber, are round, are made of barium fluoride, magnesium fluoride, zinc selenide or silicon, and are matched with the section of the photonic crystal fiber in size.

4. The tunable plasmonic crystal fiber device of claim 1, wherein: the inert working gas is helium, argon, neon or xenon; the pressure of inert working gas in the photonic crystal fiber is 1kPa-101 kPa.

5. The tunable plasmonic crystal fiber device of claim 1, wherein: the high-voltage electrode and the ground electrode are annular or spiral, the number of electrode pairs is 1-10, the electrode is made of copper, aluminum or stainless steel, and the diameter of the electrode is 1-4 mm; the distance between the high-voltage electrode and the ground electrode is 10-80 mm.

6. The tunable plasmonic crystal fiber device of claim 1, wherein: the insulating sheet is in a ring shape or umbrella skirt shape, the insulating sheet is made of quartz, ceramics, organic glass or epoxy resin, the diameter of the insulating sheet is 5-20mm, and the thickness of the insulating sheet is 0.5-3 mm; the number of the insulation sheets is 1-10, and the insulation sheets are arranged at equal intervals.

7. The tunable plasmonic crystal fiber device of claim 1, wherein: the polarity of the high-voltage pulse power supply is unipolar or positive-negative bipolar, the amplitude of output voltage is 5-30kV, the pulse repetition frequency is 1-30kHz, the pulse width is 1-20 mus, and the pulse rising edge is 0.1-2 mus.

8. The tunable plasmonic crystal fiber device of claim 1, wherein: the protection resistor is a non-inductive high-voltage-resistant resistor, the resistance range is 200-900 omega, and the power is 0.3-2 kW.

9. The tunable plasmonic crystal fiber device of claim 1, wherein: the wavelength range of incident infrared light modulated by the tunable plasma photonic crystal fiber device is 4-16 mu m.

Technical Field

The invention relates to the technical field of plasma and photonic crystal, in particular to a plasma photonic crystal fiber.

Background

The photonic crystal fiber is also called as a microstructure fiber and is divided into a band gap type photonic crystal fiber and a refractive index guide type fiber, and has wide application prospects in the fields of communication, sensing, quantum mechanics, medicine and the like. Its cross section has a more complex refractive index distribution, and besides the core region (or air holes), it usually contains hollow holes (air holes) in a periodic arrangement around the core, and the size of these hollow holes is approximately in the same order of magnitude as the wavelength of light and runs through the whole length of the device. The light wave can be limited to be transmitted in the core region of the optical fiber with low refractive index, and has the characteristics of low loss, infinite single-mode transmission, high birefringence, large mode field area and the like.

The band gap type photon crystal fiber is one kind of hollow quartz fiber with quartz-hollow hole photon crystal coating. The hollow holes are periodically arranged and distributed around the fiber core, so that the refractive index of the cross section of the cladding has periodic distribution, the Bragg diffraction effect of light propagation occurs, and a photonic band gap is formed, namely, light with corresponding wavelength cannot propagate in the cladding and can only be limited to propagate in the fiber core. The photonic band gap characteristics depend on the characteristic size, arrangement and refractive index of the hollow hole array. Once the photonic crystal fiber is prepared, the bandgap characteristics are determined, and the photonic crystal fiber cannot be used as an optical switch or an optical modulator because the structure is solidified, cannot be reconstructed and cannot be tuned.

In order to solve the above problems, the existing research proposes to coat gold, graphene or a filling liquid in the photonic crystal fiber, and adjust the refractive index of the filling material by controlling external conditions (such as voltage, magnetic field and temperature), so as to change the photonic band gap characteristics of the photonic crystal fiber and achieve tunable optical transmission. However, these methods fill solid powder or liquid into the hollow hole, and have the problems of complicated process, non-uniform coating, no reconstruction, difficult liquid injection, etc., so that the tunable photonic crystal fiber technology still stays in the laboratory stage and cannot be applied in industrial level.

The filling of low-temperature plasma in the hollow hole of the photonic crystal fiber is a new tunable mode. The plasma being in a fourth state other than gaseous, liquid and solid statesThe seed substance state is a substance state composed of a set of ions, electrons, and neutral particles and having a neutral overall state. According to the relative size of the electron temperature and the ion temperature, the plasma can be divided into high-temperature plasma and low-temperature plasma. However, implementing a tunable plasmonic crystal fiber will face the following four main problems: (1) the diameter of the hollow hole in the photonic crystal fiber is very small according to Paschen's law of gas discharge ((<50 microns), the breakdown voltage of the working gas rises rapidly; (2) high electron density of the plasma required for infrared transmission tuning>10¹⁵cm^-3) The conventional gas discharge mode is difficult to realize; (3) under the condition of low-temperature plasma with small size and high density, the heating problem of the photonic crystal fiber is serious; (4) the low-temperature plasma filling is not easy to be uniform, so that photonic band gap characteristics in the photonic crystal fiber have larger difference, and the infrared light transmission tuning effect is influenced.

Disclosure of Invention

In order to solve the technical problems mentioned in the background art, the invention provides a tunable plasma photonic crystal fiber device.

In order to achieve the technical purpose, the technical scheme of the invention is as follows:

a tunable plasma photonic crystal fiber device comprises a photonic crystal fiber, a high-voltage pulse power supply, a protective resistor, a high-voltage electrode, an insulating sheet, a ground electrode, an incident Brewster window and an emergent Brewster window; the photonic crystal fiber is internally provided with a periodically arranged hollow hole array, each hollow hole penetrates through two ends of the photonic crystal fiber, and inert working gas is filled in each hollow hole; the incident Brewster window and the emergent Brewster window allow infrared light to penetrate through, are respectively arranged at two ends of the photonic crystal fiber, and seal the space between the two Brewster windows and the two ends of the photonic crystal fiber; the high-voltage electrode, the insulating sheet and the ground electrode are respectively in close contact with the surface of the photonic crystal fiber, the insulating sheet is arranged between the high-voltage electrode and the ground electrode, the output end of the high-voltage pulse power supply is electrically connected with the high-voltage electrode through a protective resistor, and the grounding end of the high-voltage pulse power supply is electrically connected with the ground electrode; infrared laser enters the photonic crystal fiber through the incident Brewster window and is emitted from the emergent Brewster window, the high-voltage pulse power supply applies pulse voltage to the high-voltage electrode, and low-temperature plasma is obtained in the hollow hole filled with inert working gas in a dielectric barrier porous discharge mode, so that the photonic crystal fiber filled with the plasma is realized; by changing the pulse parameters of the high-voltage power supply, the gas pressure of the inert working gas or the distance between the high-voltage electrode and the ground electrode, the characteristic physical parameters and the gas temperature of the plasma can be adjusted, and the infrared band gap characteristic of the photonic crystal fiber can be tuned in a wide range.

Furthermore, the hollow hole array is distributed in a circular shape, a ring shape, a rectangular shape or a pentagonal shape, the number of the hollow holes is 3-120, and the inner diameter of each hollow hole is 3-45 mu m; the fiber core of the photonic crystal fiber is a single core or a double core, the diameter of the fiber core is 10-60 mu m, and the material of the fiber core is quartz, pure silicon or air holes; the diameter of the cross section of the photonic crystal fiber is less than 1mm, and the length of the photonic crystal fiber is 80-200 mm.

Furthermore, the two Brewster windows respectively have a Brewster angle with the vertical section of the photonic crystal fiber, are round, are made of barium fluoride, magnesium fluoride, zinc selenide or silicon, and are matched with the section of the photonic crystal fiber in size.

Further, the inert working gas is helium, argon, neon or xenon; the pressure of inert working gas in the photonic crystal fiber is 1kPa-101 kPa.

Furthermore, the high-voltage electrode and the ground electrode are annular or spiral, the number of electrode pairs is 1-10, the material of the electrode is copper, aluminum or stainless steel, and the diameter of the electrode is 1-4 mm; the distance between the high-voltage electrode and the ground electrode is 10-80 mm.

Furthermore, the insulating sheet is in a circular ring shape or umbrella skirt shape, the insulating sheet is made of quartz, ceramic, organic glass or epoxy resin, the diameter of the insulating sheet is 5-20mm, and the thickness of the insulating sheet is 0.5-3 mm; the number of the insulation sheets is 1-10, and the insulation sheets are arranged at equal intervals.

Furthermore, the polarity of the high-voltage pulse power supply is unipolar or positive-negative bipolar, the amplitude of the output voltage is 5-30kV, the pulse repetition frequency is 1-30kHz, the pulse width is 1-20 mus, and the pulse rising edge is 0.1-2 mus.

Furthermore, the protection resistor is a non-inductive high-voltage-resistant resistor, the resistance range is 200-900 omega, and the power is 0.3-2 kW.

Further, the wavelength range of incident infrared light modulated by the tunable plasma photonic crystal fiber is 4-16 μm.

Adopt the beneficial effect that above-mentioned technical scheme brought:

(1) compared with the adoption of solid powder or liquid, the invention adopts dielectric barrier porous discharge to realize that low-temperature plasma fills the tiny hollow holes of the photonic crystal fiber, and the filling process is simple;

(2) the generation and disappearance of the low-temperature plasma can be controlled by an external high-voltage pulse power supply, namely, the electric control, and the method has the characteristics of reconfiguration and high response speed;

(3) the invention adopts inert gas, a double-electrode structure and an insulating sheet, so that the gas breakdown voltage in the photonic crystal fiber is reduced;

(4) the invention adopts the high-voltage pulse power supply to drive the low-temperature plasma, can generate the plasma with high electron density, and is easy to control the gas temperature in the photonic crystal fiber;

(5) the invention adopts a high-voltage pulse power supply to drive the dielectric barrier porous discharge, so that the low-temperature plasma is uniformly filled;

(6) according to the invention, the infrared band gap characteristics of the photonic crystal fiber can be continuously tuned in a wide wavelength range by flexibly regulating and controlling the parameters of the high-voltage pulse power supply or the air pressure of the working gas or the electrode spacing;

(7) the invention adopts a dielectric barrier porous discharge structure and a Brewster window, and avoids laser scattering or deflection and the like caused by the transmission of infrared laser in the photonic crystal fiber due to the design of an electrode structure.

Drawings

FIG. 1 is an overall schematic diagram of an embodiment of the present invention;

FIG. 2 is a three-dimensional structure diagram of a photonic crystal fiber, an electrode and an insulation sheet according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a photonic crystal fiber according to an embodiment of the present invention;

fig. 4 is a graph of an infrared bandgap signature of an embodiment of the present invention.

Description of reference numerals: 1. an infrared laser; 2. an incident brewster window; 3. an inert working gas; 4. quartz; 5. an array of hollow holes; 6. high-voltage electrode, 7, insulating sheet; 8. a ground electrode; 9. emitting a Brewster window; 10. a beam splitter; 11. measuring the polarization state; 12. a photomultiplier tube; 13. a protection resistor; 14. a high voltage pulse power supply; 15. a core.

Detailed Description

The technical scheme of the invention is explained in detail in the following with the accompanying drawings.

As shown in fig. 1, the tunable plasma photonic crystal fiber device provided by the present invention includes an incident brewster window 2, an inert working gas 3, a photonic crystal fiber (including quartz 4, a hollow hole array 5, and a fiber core 15), a high voltage electrode 6, an insulating sheet 7, a ground electrode 8, an exit brewster window 9, a protection resistor 13, and a high voltage pulse power supply 14. In order to cooperate with the implementation of the device, an infrared laser 1, a beam splitter 10, a polarization state measuring instrument 11 and a photomultiplier tube 12 are also provided. As shown in fig. 2, the photonic crystal fiber is of a quartz-hollow hole band gap type, hollow hole arrays 5 are periodically arranged in the photonic crystal fiber, hollow holes penetrate through two ends of the photonic crystal fiber, and inert working gas 3 is filled in the hollow holes. The two ends of the photonic crystal fiber are externally connected with Brewster windows 2 and 9, the ports are sealed, the inert working gas 3 can be sealed in the photonic crystal fiber, the Brewster windows allow infrared laser to enter and exit, S polarization can be filtered, and the incident laser is changed into specific p polarization. The surface of the photonic crystal fiber is in close contact with the high-voltage electrode 6, the ground electrode 8 and the insulating sheet 7. The high-voltage electrode 6 is electrically connected to a high-voltage output terminal of the high-voltage pulse power supply 14 through a protective resistor 13, and the ground electrode 8 is connected to a ground terminal of the high-voltage pulse power supply 14. And the breakdown voltage can be reduced by adopting inert working gas and reasonably designing the structure and the distance of the two electrodes. From the electrical connection point of view, two parallel branches exist between the high-voltage electrode and the ground electrode, namely a series branch containing the porous array of the photonic crystal fiber and inert working gas, and a series branch containing air around the photonic crystal fiber and an insulating sheet. The insulating sheet is arranged between the two electrodes, so that the phenomenon that the air insulation is broken down to cause short circuit between the two electrodes can be avoided. The high-voltage pulse power supply has the advantages of rapid rising edge and flexible and adjustable multi-parameter, can provide higher breakdown voltage than an alternating-current power supply, and generates porous low-temperature plasma with high electron density, controllable temperature and more uniformity. Therefore, pulse voltage is applied to the electrode, and low-temperature plasma can be obtained in the hollow hole filled with inert working gas through the form of dielectric barrier porous discharge, so that the photonic crystal fiber filled with the plasma is realized. By changing the parameters of the high-voltage pulse power supply or the gas pressure or the electrode spacing of the working gas, the characteristic physical parameters (such as electron density and plasma size) and the gas temperature of the plasma can be adjusted, and the infrared band gap characteristic of the photonic crystal fiber can be tuned in a wide range.

In the embodiment, the hollow hole array 5 is distributed in a circular, annular, rectangular or pentagonal shape, the number of the hollow holes is 3-120, and the inner diameter of the hollow holes is 3-45 μm. The fiber core 15 of the photonic crystal fiber is a single core or a double core, the diameter of the fiber core is 10-60 mu m, and the material of the fiber core is quartz, pure silicon or air holes; the diameter of the cross section of the photonic crystal fiber is less than 1mm, and the length of the photonic crystal fiber is 80-200 mm. Fig. 3 is a schematic cross-sectional view of a fiber with a circular hollow hole array 5.

In this embodiment, the two brewster windows 2 and 9 respectively have a brewster angle with respect to the vertical cross section of the photonic crystal fiber, the windows are circular, the windows are made of barium fluoride, magnesium fluoride, zinc selenide or silicon, and the size of the windows is matched with the size of the cross section of the photonic crystal fiber.

In the present embodiment, the inert working gas 3 is helium, argon, neon or xenon; the pressure of inert working gas in the photonic crystal fiber is 1kPa-101 kPa.

In this embodiment, the high voltage electrode 6 and the ground electrode 8 are annular or spiral, the number of electrode pairs is 1-10, the material of the electrodes is copper, aluminum or stainless steel, and the diameter of the electrodes is 1-4 mm; the distance between the high-voltage electrode 6 and the ground electrode 8 is 10-80 mm.

In this embodiment, the insulating sheet 7 is circular or umbrella skirt-shaped, the insulating sheet 7 is made of quartz, ceramic, organic glass or epoxy resin, and the insulating sheet 7 has a diameter of 5-20mm and a thickness of 0.5-3 mm; the number of the insulating sheets 7 is 1-10, and the insulating sheets are arranged at equal intervals.

In this embodiment, the polarity of the high voltage pulse power supply 14 is unipolar or bipolar, the output voltage amplitude is 5-30kV, the pulse repetition frequency is 1-30kHz, the pulse width is 1-20 mus, and the pulse rising edge is 0.1-2 mus.

In this embodiment, the protection resistor is a non-inductive high-voltage-resistant resistor with a resistance range of 200 Ω and 900 Ω, and a power of 0.3-2 kW.

In this embodiment, the wavelength range of the incident infrared light modulated by the tunable plasmonic crystal fiber is 4-16 μm.

In the embodiment, the infrared laser 1 adopts a Daylight ü ber Tuner, the output infrared laser wavelength is 4-10 μm, the beam splitter 10 adopts a Thorlabs beam splitting cube, the polarization state measuring instrument 11 adopts a high-precision polarization state measuring system of hinds company, and the photomultiplier 12 adopts a Hamamatsu H10721-01 nanosecond fast response type photomultiplier for detecting the laser radiation intensity.

The working process of the embodiment is as follows:

on the premise that the whole device is arranged, the high-voltage pulse power supply 14 is started, and the power supply parameters are adjusted to be within the parameter range. High-voltage pulses are applied to the high-voltage electrode 6, dielectric barrier porous discharge is generated, uniform low-temperature plasmas can be obtained in the hollow holes filled with helium, and the photonic crystal fiber filled with the low-temperature plasmas is realized. The high voltage pulse power supply 14 is turned on and off to control the generation and extinction of the low temperature plasma. Adjusting the parameters of the high voltage pulse power supply 14 can make the electron density of the low temperature plasma at 10¹⁶-10¹⁸cm^-3Internal change, gas temperature changes within 350-600K. Therefore, adjusting the parameters of the high voltage pulsed power supply 14 can change the characteristic physical parameters of the low temperature plasma. As shown in fig. 4, when the electron density is from 10¹⁷cm^-3Is raised to 10¹⁸cm^-3When the photonic crystal fiber is used, the infrared band gap characteristics corresponding to the wavelength within the range of 7.2-8.8 mu m are obviously changed, and the central frequency of the band gap deviates 0.1 mu m. The test procedure was as follows: and starting the infrared laser 1, setting the wavelength and the scanning step length after the infrared laser is stabilized, outputting the infrared laser, and enabling the infrared laser to reach the beam splitter 10 through the incident Brewster window 2, the photonic crystal fiber and the emergent Brewster window 9. The laser beam is split into two beams, one beam enters the photomultiplier tube 12 and the other beam enters the polarization state measuring instrument 11. And opening and closing the low-temperature plasma, and observing the radiation intensity and polarization state change of the infrared laser with different wavelengths according to output signals of the photomultiplier and the polarization state measuring instrument. The characteristic physical parameters of the low-temperature plasma are adjusted by changing the parameters of the high-voltage pulse power supply 14, so that the polarization state and the radiation intensity of the infrared laser under different wavelengths are adjusted, and the purpose of tuning in a wide range is achieved. Therefore, the invention has the advantages of more uniform filling of plasma, simple process, convenient tuning and reconfigurability, and can be used as an infrared optical fiber switch or an infrared modulator.