Hollow-core optical fiber mixed gas laser

Abstract

The invention provides a hollow-core optical fiber mixed gas laser. The hollow-core optical fiber mixed gas laser comprises a pump laser, a reflecting mirror, a dichroic mirror, a coupling lens, an input sealing cavity, an output sealing cavity, a vacuumizing and inflating system, a hollow-core optical fiber and a collimating lens. Laser beams output by a pump laser are combined and then coupled into a hollow-core optical fiber, the hollow-core optical fiber is vacuumized and then filled with corresponding gain gas, and laser output of various different wavebands is generated by simultaneously filling at least two kinds of gain gas into the same section of hollow-core optical fiber, so that a wider output waveband is obtained; the output wave band range of the hollow-core optical fiber gas laser is improved, the gas pressure of the gain gas is controlled, and the output power of the hollow-core optical fiber gas laser is improved. By adopting the optical fiber structure, the hollow-core optical fiber mixed gas laser is simple and compact in structure, high in stability and high in light beam quality.

Description

Technical Field

[0001] The invention belongs to the technical field of optical fiber lasers, and in particular relates to a hollow-core optical fiber mixed-gas laser. Background Art

[0002] As an important means of outputting portable, stable and efficient lasers, fiber lasers have good beam quality and compact structure, and have great development prospects in the field of lasers. In particular, in the fields of medical treatment, material processing, national defense and sensing, the number of applications of lasers requiring high average power, compact portable size, high reliability and long-distance beam propagation capabilities is increasing rapidly.

[0003] The hollow-core fiber-based gas laser is a new type of laser light source developed with the emergence of hollow-core fiber. It combines many advantages of traditional gas lasers and fiber lasers and has received widespread attention in recent years. Fiber gas lasers use hollow-core fiber as the transmission carrier of the laser and gas molecules as the gain medium. They combine the advantages of fiber lasers and gas lasers, and have a long action distance, good beam quality, good heat dissipation characteristics, and a high damage threshold. At the same time, different types of gain gases (such as CO2, CO, HF, etc.) can be replaced to output lasers of different wavelengths.

[0004] Common fiber gas lasers are usually filled with only one gain gas. In terms of output band, the output spectrum that can be obtained with a single gain gas is limited, and the output line width of the pump source is required to be high. Summary of the invention

[0005] In view of the defects of the prior art, the present invention proposes a hollow-core fiber mixed gas laser to obtain a laser light source with a wide output band range, high beam quality and flexible transmission.

[0006] In order to achieve the above technical objectives, the specific technical solutions adopted by the present invention are as follows: Hollow core fiber mixed gas laser, including pump laser, reflector, dichroic mirror, coupling lens, input sealed cavity, output sealed cavity, vacuum and gas filling system, hollow core fiber, collimating lens; The pump laser output by the pump laser is injected into the dichroic mirror after adjusting the optical path through the reflector. The dichroic mirror combines the pump laser beam and injects it into the coupling lens. The coupling lens couples the combined pump laser beam into the hollow-core optical fiber. The input end and the output end of the hollow-core optical fiber are sealed in the input sealed cavity and the output sealed cavity respectively. The vacuum pumping and gas filling system is connected to the input sealed cavity or the output sealed cavity. The vacuum pumping and gas filling system is used to vacuum the hollow-core optical fiber and fill at least two gain gases with set air pressure into the hollow-core optical fiber, and control the air pressure of a single gain gas in the hollow-core optical fiber not to exceed 2mbar, and the total air pressure of the gain gas in the hollow-core optical fiber not to exceed 3mbar. After the pump laser interacts with the at least two gain gases in the hollow-core optical fiber, a pump laser with a wide output wavelength range is output. The pump laser with a wide output wavelength range output by the hollow-core optical fiber is collimated by the collimating lens and then emitted.

[0007] Furthermore, the number of the pump lasers corresponds to the type of gain gas, and the pump lasers are narrow-linewidth laser light sources whose central wavelengths correspond to the absorption lines of the gain gas.

[0008] Furthermore, the reflector is a plane reflector with high reflectivity corresponding to the central wavelength of the pump laser.

[0009] Furthermore, the dichroic mirror is a plane dichroic mirror having high reflectivity for the pump laser wave band incident after adjustment by the reflector and high transmittance for the pump laser wave band incident directly.

[0010] Furthermore, the coupling lens is a positive lens with high transmittance to the pump laser band, and the coupling lens can focus the pump beam to match the hollow-core optical fiber mode field.

[0011] Furthermore, the input sealed cavity and the output sealed cavity are respectively provided with an input window plate and an output window plate; the input window plate has high transmittance to the pump laser band and the output laser band; the output window plate has high transmittance to the output laser band.

[0012] Furthermore, the vacuuming and charging system includes a vacuum pump, a gas cylinder, a pressure regulating valve, and a barometer, which are used to adjust and monitor the pressure of the gain gas in the hollow-core optical fiber.

[0013] Furthermore, the hollow core optical fiber can transmit the pump laser band and the output laser band with low loss.

[0014] Furthermore, the collimating lens is a positive lens with high transmittance to the output laser wavelength band.

[0015] Furthermore, the gain gas includes but is not limited to carbon monoxide, carbon dioxide, hydrogen bromide, and acetylene.

[0016] The beneficial effects of the present invention are as follows: The present invention adopts at least two gases as gain gases at the same time, and generates laser outputs of multiple different bands at the same time through stimulated radiation of different gases, thereby obtaining a wider output band and improving the output band range of the hollow-core fiber gas laser. In principle, the pump laser pumps the gain gas molecules from the ground state to the excited state by aligning the P-branch or R-branch absorption line of the gain gas, and the excited-state gain gas molecules transition to the lower laser energy level through stimulated radiation to output mid-infrared lasers; at the same time, the mutual collision between at least two gain gas molecules will change the energy level relaxation rate, thereby improving the laser output power and efficiency, and filling the hollow-core fiber with at least two gain gases can further improve the gas collision broadening, thereby improving the absorption line width of each gas and reducing the output line width requirements for the pump source; in the present invention, the stability of the laser output power will not be reduced after filling at least two gain gases; the present invention also improves the output power of the hollow-core fiber mixed gas laser by controlling the gas pressure of the gain gas in the hollow-core fiber.

[0017] The present invention adopts an optical fiber structure, and the light is bound in a hollow core optical fiber, which is not easily affected by the external environment. Therefore, the present invention has the advantages of simple and compact structure, high stability, high light beam quality, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of the structure of a hollow-core fiber mixed-gas laser provided in an embodiment; Figure 2 An output spectrum diagram of an embodiment provided by simultaneously charging HBr and CO gases; Figure 3 A diagram showing the effect of gas pressure on the output power of a hollow-core fiber mixed-gas laser when CO gas is filled into 1.49 mbar HBr gas provided in an embodiment; Figure 4 A diagram showing the effect of gas pressure on the output power of a hollow-core fiber mixed-gas laser when CO gas is filled into 3 mbar HBr gas provided in an embodiment; Figure 5 A diagram showing the effect of gas pressure on the output power of a hollow-core fiber mixed-gas laser when HBr gas is filled into 2.2 mbar CO gas provided in an embodiment; Figure 6A diagram showing the effect of gas pressure on the output power of a hollow-core fiber mixed-gas laser when HBr gas is filled into 5.2 mbar CO gas provided in an embodiment; Figure 7 A schematic diagram of the output power of a hollow-core fiber mixed-gas laser provided in an embodiment; Figure 8 A diagram showing the effect of gas pressure changes on the CO absorption line width increase in a hollow-core fiber mixed-gas laser provided in an embodiment; Fig. 9 This is a diagram showing the effect of gas pressure changes on the HBr absorption linewidth increase in a hollow-core fiber mixed-gas laser provided in an embodiment.

[0020] Figure annotation: 1. The first pump laser; 2. The second pump laser; 3. The reflector; 4. The dichroic mirror; 5. The coupling lens; 6. The input window; 7. The input sealed cavity; 8. The vacuum pumping and inflation system; 9. The hollow core optical fiber; 10. The output sealed cavity; 11. The output window; 12. The collimating lens. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In one embodiment, the hollow core fiber mixed gas laser includes a first pump laser 1, a second pump laser 2, a reflector 3, a dichroic mirror 4, a coupling lens 5, an input window 6, an input sealed cavity 7, a vacuum pumping and gas filling system 8, a hollow core fiber 9, an output sealed cavity 10, an output window 11, and a collimating lens 12; The first pump laser output by the first pump laser 1 passes through the reflector 3 and the dichroic mirror 4 in sequence, and is combined with the second pump laser output by the second pump laser 2 through the dichroic mirror 4. The combined pump laser is focused by the coupling lens 5 to achieve mode field matching between the pump laser and the core of the hollow core optical fiber 9. The pump laser is coupled to the core of the hollow core optical fiber 9 through the input window 6. The input end and the output end of the hollow core optical fiber 9 are respectively sealed in the input sealed cavity 7 and the output sealed cavity 10; the vacuum and gas filling system 8 is connected to the input sealed cavity 7 or the output sealed cavity 10, and the vacuum and gas filling system 8 is used to vacuum the hollow core optical fiber 9 and fill the hollow core optical fiber 9 with at least two gain gases of set air pressure, and control the single gain gas in the hollow core optical fiber 9. The gas pressure of the gain gas does not exceed 2 mbar, and the total gas pressure of the gain gas in the hollow-core optical fiber 9 does not exceed 3 mbar; the hollow-core optical fiber 9 effectively confines the pump laser in the fiber core, providing an effective interaction distance between the pump laser and the gain gas; after the hollow-core optical fiber 9 is filled with at least two gain gases, on the one hand, the radiation spectrum range of the laser can be increased, and on the other hand, the collision between the gain gas molecules can be enhanced, the absorption line width of the gas molecules can be increased, and the energy level life of the gain gas can be improved; after the pump laser interacts with the multiple gain gases in the hollow-core optical fiber 9, a pump laser with a wide output wavelength range is output, and the pump laser with a wide output wavelength range output by the hollow-core optical fiber 9 passes through the output window plate 11 and is collimated by the collimating lens 12 and then emitted.

[0023] like Figure 1 In one embodiment, the hollow-core fiber mixed gas laser includes a first pump laser 1, a second pump laser 2, a reflector 3, a dichroic mirror 4, a coupling lens 5, an input window 6, an input sealed cavity 7, a vacuum pumping and gas filling system 8, a hollow-core fiber 9, an output sealed cavity 10, an output window 11, and a collimating lens 12; The first pump laser output by the first pump laser 1 passes through the reflector 3 and the dichroic mirror 4 in sequence, and is combined with the second pump laser output by the second pump laser 2 through the dichroic mirror 4. The combined pump laser is focused by the coupling lens 5 to achieve mode field matching between the pump laser and the core of the hollow core optical fiber 9. The pump laser is coupled to the core of the hollow core optical fiber 9 through the input window piece 6. The input end and the output end of the hollow core optical fiber 9 are respectively sealed in the input sealed cavity 7 and the output sealed cavity 10; the vacuum pumping and inflation system 8 is connected to the input sealed cavity 7 or the output sealed cavity 10, and the vacuum pumping and inflation system 8 is connected to the input sealed cavity 7 or the output sealed cavity 10. The vacuum and gas filling system 8 is used to evacuate the hollow core optical fiber 9 and fill 1 mbar of HBr gas and 0.1 mbar of CO gas into the hollow core optical fiber 9; the hollow core optical fiber 9 effectively confines the pump laser in the fiber core, providing an effective interaction distance between the pump laser and the HBr and CO gases; the pump laser interacts with the HBr and CO gases in the hollow core optical fiber 9 to output a pump laser with a wide output wavelength range, and the pump laser with a wide output wavelength range output by the hollow core optical fiber 9 passes through the output window 11 and is collimated by the collimating lens 12 before being emitted.

[0024] The first pump laser 1 is a Tm fiber laser with a central wavelength of 1971.67 nm and a line width of 10 MHz; the second pump laser 2 is a Tm fiber laser with a central wavelength of 2331.93 and a line width of 10 MHz.

[0025] The reflector 3 is a plane reflector with a silver film coated on the surface, and has a high reflectivity for laser with a central wavelength of 1971.67 nm.

[0026] The dichroic mirror 4 is a plane dichroic mirror with a dichroic film coated on its surface, and has high reflectivity for lasers with a central wavelength of 1971.67 nm and high transmittance for lasers with a central wavelength of 2331.93 nm.

[0027] The coupling lens 5 is a plano-convex lens with a focal length of 50 mm, has high transmittance to lasers with central wavelengths of 1971.67 nm and 2331.93 nm, and can focus the pump beam to match the hollow-core optical fiber mode field.

[0028] The input sealed cavity 7 and the output sealed cavity 10 are respectively provided with an input window 6 and an output window 11; the input window 6 is a plane glass window with high transmittance to lasers with central wavelengths of 1971.67nm and 2331.93nm; the output window 11 is a plane glass window with high transmittance to lasers in the 3.5-4.8μm band.

[0029] The hollow core optical fiber 9 has low transmission loss for lasers in the wavelength bands of 1971.67 nm, 2331.93 nm and 3.5-4.8 μm.

[0030] The collimating lens 12 is a plano-convex lens and has high transmittance to 3.5-4.8 μm laser.

[0031] like Figure 2 As shown, Figure 2 This is an output spectrum diagram of an embodiment provided by simultaneously filling HBr and CO gases. As can be seen from the figure, the simultaneous filling of HBr and CO gases simultaneously generates laser output, indicating that the hollow-core fiber mixed gas laser provided by the present invention can operate when simultaneously filling HBr and CO gases.

[0032] In a hollow-core fiber mixed gas laser, the more HBr and CO gas are filled into the hollow-core fiber, the better. When the HBr gas in the hollow-core fiber is constant, the amount of CO gas filled into the hollow-core fiber will affect the output power of the hollow-core fiber mixed gas laser. Specifically, Figure 3 The effect of the CO gas pressure in 1.49mbarHBr gas on the output power of the hollow-core fiber mixed gas laser provided in an embodiment. In this embodiment, the central wavelength of the first pump laser is 1971.67nm, the output line width is less than 10MHz, and the output power is kept constant at 3W; the central wavelength of the second pump laser is 2331.93, the output line width is less than 10MHz, the output power is kept constant at 1W, the hollow-core fiber length is 5m, and the core diameter is 100μm. Figure 3 It can be seen that at the initial moment, the hollow-core fiber mixed gas laser is only filled with HBr gas, and the gas pressure of HBr gas is 1.49mbar. At this time, the output power of the hollow-core fiber mixed gas laser is about 2.7mW. Use the vacuum pumping and gas filling system to fill CO gas into the hollow-core fiber, and monitor the output power of the hollow-core fiber mixed gas laser in real time. Figure 3 It can be seen that the amount of CO gas filled will affect the output power of the hollow-core fiber mixed gas laser. When 0.1mbar of CO gas is filled, the output power of the hollow-core fiber mixed gas laser reaches the maximum value, and then as the CO gas filled in the hollow-core fiber increases, the output power of the hollow-core fiber mixed gas laser continues to decrease. When the CO gas filled in the hollow-core fiber exceeds 0.3mbar, the output power of the hollow-core fiber mixed gas laser will begin to gradually decrease from the output power of the hollow-core fiber mixed gas laser when only 1.49mbar of HBr gas is filled at the initial moment.

[0033] like Figure 4 As shown, Figure 4 The effect of gas pressure on the output power of a hollow-core fiber mixed-gas laser when CO gas is filled into 3 mbar HBr gas provided in an embodiment. Figure 3 The embodiment shown is the same, from Figure 4It can be seen that at the initial moment, the hollow-core fiber gas-filled laser is only filled with HBr gas, and the gas pressure of HBr gas is 3mbar. At this time, the output power of the hollow-core fiber gas-filled laser is about 4.2mW. CO gas is filled into the hollow-core fiber using the vacuum pumping and gas filling system, and the output power of the hollow-core fiber gas-filled laser is monitored in real time. Figure 4 It can be seen that the amount of CO gas filled will affect the output power of the hollow-core fiber mixed gas laser. Then, as the CO gas filled in the hollow-core fiber increases, the output power of the hollow-core fiber mixed gas laser decreases continuously. This shows that when the HBr gas pressure filled in the hollow-core fiber mixed gas laser is too high, the filling of CO gas will reduce the output power of the hollow-core fiber mixed gas laser.

[0034] like Figure 5 As shown, Figure 5 The effect of gas pressure on the output power of a hollow-core fiber mixed gas laser when HBr gas is filled into 2.2 mbar CO gas provided in an embodiment. Figure 3 The embodiment shown is the same, from Figure 5 It can be seen that at the initial moment, the hollow-core fiber mixed gas laser is only filled with CO gas, and the CO gas pressure is 2.2mbar. At this time, the output power of the hollow-core fiber mixed gas laser is about 5.4mW. Use the vacuum pumping and gas filling system to fill HBr gas into the hollow-core fiber, and monitor the output power of the hollow-core fiber mixed gas laser in real time. Figure 5 It can be seen that the amount of HBr gas filled will affect the output power of the hollow-core fiber mixed gas laser. When 0.8 mbar of HBr gas is filled, the output power of the hollow-core fiber mixed gas laser reaches the maximum value, and then as the HBr gas filled in the hollow-core fiber increases, the output power of the hollow-core fiber mixed gas laser continues to decrease. When the HBr gas filled in the hollow-core fiber exceeds 2.9 mbar, the output power of the hollow-core fiber mixed gas laser will begin to gradually decrease from the output power of the hollow-core fiber mixed gas laser when only 2.2 mbar of CO gas is filled at the initial moment.

[0035] like Figure 6 As shown, Figure 6 The effect of gas pressure on the output power of a hollow-core fiber mixed gas laser when HBr gas is filled into 5.2 mbar CO gas provided in an embodiment. Figure 3 The embodiment shown is the same, from Figure 6It can be seen that at the initial moment, the hollow-core fiber mixed gas laser is only filled with CO gas, and the CO gas pressure is 5.2mbar. At this time, the output power of the hollow-core fiber mixed gas laser is about 2.4mW. Use the vacuum pumping and gas filling system to fill HBr gas into the hollow-core fiber, and monitor the output power of the hollow-core fiber mixed gas laser in real time. Figure 6 It can be seen that the amount of HBr gas filled will affect the output power of the hollow-core fiber mixed gas laser. Then, as the amount of HBr gas filled in the hollow-core fiber increases, the output power of the hollow-core fiber mixed gas laser continues to decrease. This shows that when the CO gas pressure filled in the hollow-core fiber mixed gas laser is too high, filling with HBr gas will reduce the output power of the hollow-core fiber mixed gas laser.

[0036] When the gain gases filled in the hollow-core fiber are CO and HBr, the gas pressure of a single gain gas should not exceed 2 mbar, and the total gas pressure of the gain gas filled in the hollow-core fiber should not exceed 3 mbar; if the total gas pressure of the gain gas filled in the hollow-core fiber exceeds 3 mbar, it will not only fail to increase the output power of the hollow-core fiber mixed gas laser, but will cause the output power of the hollow-core fiber mixed gas laser to decrease.

[0037] like Figure 7 As shown, Figure 7 A schematic diagram of the output power of a hollow-core fiber mixed gas laser provided in an embodiment. Figure 3 The embodiment shown is the same. The root mean square of the output power of the hollow-core fiber mixed gas laser in the figure is 1.1%, indicating that the hollow-core fiber mixed gas laser has good power stability.

[0038] like Figure 8 As shown, Figure 8 The effect of the change of gas pressure in the hollow-core fiber mixed gas laser on the increase of the CO absorption line width is shown in the figure. It can be seen from the figure that as the total gas pressure in the hollow-core fiber increases, the increase of the CO absorption line width also increases; Fig. 9 , Fig. 9 The figure is a diagram showing the effect of the change in gas pressure on the HBr absorption line width increase in a hollow-core fiber mixed gas laser provided in an embodiment. It can be seen from the figure that as the total gas pressure in the hollow-core fiber increases, the HBr absorption line width increase also increases. This shows that the hollow-core fiber mixed gas laser provided by the present invention can increase the absorption line width of the gain gas, thereby reducing the output line width requirement for the pump source.

[0039] Matters not covered by the present invention are known technologies.

[0040] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0041] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Hollow core fiber mixed gas laser, characterized in that: It includes pump laser, reflector, dichroic mirror, coupling lens, input sealed cavity, output sealed cavity, vacuum pumping and gas filling system, hollow core optical fiber and collimating lens; The pump laser output by the pump laser is injected into the dichroic mirror after adjusting the optical path through the reflector. The dichroic mirror combines the pump laser beam and injects it into the coupling lens. The coupling lens couples the combined pump laser beam into the hollow-core optical fiber. The input end and the output end of the hollow-core optical fiber are sealed in the input sealed cavity and the output sealed cavity respectively. The vacuum pumping and gas filling system is connected to the input sealed cavity or the output sealed cavity. The vacuum pumping and gas filling system is used to vacuum the hollow-core optical fiber and fill at least two gain gases with set air pressure into the hollow-core optical fiber, and control the air pressure of a single gain gas in the hollow-core optical fiber not to exceed 2mbar, and the total air pressure of the gain gas in the hollow-core optical fiber not to exceed 3mbar. After the pump laser interacts with the at least two gain gases in the hollow-core optical fiber, a pump laser with a wide output wavelength range is output. The pump laser with a wide output wavelength range output by the hollow-core optical fiber is collimated by the collimating lens and then emitted.

2. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The number of the pump lasers corresponds to the type of gain gas, and the pump lasers are narrow-linewidth laser light sources whose central wavelengths correspond to the absorption lines of the gain gas.

3. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The reflector is a plane reflector with high reflectivity corresponding to the central wavelength of the pump laser.

4. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The dichroic mirror is a plane dichroic mirror which has high reflectivity for the pump laser wave band incident after adjustment by the reflector and high transmittance for the pump laser wave band incident directly.

5. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The coupling lens is a positive lens with high transmittance to the pump laser band, and the coupling lens can focus the pump beam to match the hollow-core optical fiber mode field.

6. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The input sealed cavity and the output sealed cavity are respectively provided with an input window plate and an output window plate; the input window plate has high transmittance to the pump laser band and the output laser band; the output window plate has high transmittance to the output laser band.

7. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The vacuuming and gas filling system comprises a vacuum pump, a gas cylinder, a gas pressure regulating valve and a barometer, and is used to adjust and monitor the gas pressure of the gain gas in the hollow core optical fiber.

8. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The hollow core optical fiber can transmit the pump laser band and the output laser band with low loss.

9. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The collimating lens is a positive lens with high transmittance to the output laser wavelength band.

10. The hollow-core fiber mixed-gas laser according to claim 1, characterized in that: The gain gas includes but is not limited to carbon monoxide, carbon dioxide, hydrogen bromide, and acetylene.

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