High-power mid-infrared nanosecond pulse hollow-core optical fiber gas laser

Abstract

The invention discloses a high-power mid-infrared nanosecond pulse hollow-core optical fiber gas laser. Pump light of a pumping source is output to a lens through an optical fiber. The lens comprises a plano-convex lens and a reflecting mirror which are in primary light path connection, and the reflecting mirror and the plano-convex lens focus the pump light; and the gas chamber A is used for loading the hollow-core anti-resonance optical fiber and filling gas. And the focused pump light is coupled into the hollow-core anti-resonance optical fiber through the window. And the gas chamber B is used for loading the hollow-core anti-resonance optical fiber and sealing the gas. And the intermediate infrared band-pass optical filter of the intermediate infrared band-pass optical filter is placed at the tail end of the hollow-core optical fiber and is used for filtering residual pump light. By combining the double advantages of the hollow-core optical fiber and the traditional gas laser, the laser has the characteristics of abundant emission wavelength, high output power, good light beam quality and the like; the method has important application in the fields of military photoelectric countermeasure, laser medical treatment, trace gas detection and the like.

Description

Technical Field

[0001] This invention relates to a high-power mid-infrared nanosecond pulsed hollow fiber gas laser, belonging to the field of mid-infrared laser application technology. Background Technology

[0002] Currently, mid-infrared lasers are generated using methods including solid-state lasers, fiber lasers, quantum cascade lasers, gas lasers, and chemical lasers. Among these, fiber lasers, with their high optical-to-optical conversion efficiency, compact structure, and good beam quality, have become a research hotspot both domestically and internationally. Common rare-earth ions used in fiber lasers include erbium ions (Er). 3+ Thulium ions (Tm 3+ ), ytterbium ions (Yb 3+ ), holmium ions (Ho) 3+ ) and dysprosium ions (Dy 3+ )wait.

[0003] In existing technologies, limited by the luminescence range of rare-earth ions and the light-guiding range of the matrix material, the output wavelength of rare-earth-doped soft glass fiber lasers is mostly concentrated in the 1~4µm band. Rare-earth-doped fibers have various glass matrices, such as silicate glass, fluoride glass, telluride glass, and chalcogenide glass. Silicate glass has a high phonon energy (~1100 cm⁻¹). -1 Mid-infrared lasers exhibit strong absorption of light with wavelengths greater than 2.2µm, which is detrimental to their generation and transmission. "Soft glasses," such as fluoride glasses, telluride glasses, and chalcogenide glasses, have lower phonon energies and weaker absorption of mid-infrared lasers. However, soft glasses suffer from poor physicochemical properties, exhibiting issues like material deliquescence and poor resistance to optical damage, thus limiting the improvement of mid-infrared fiber laser power levels. Summary of the Invention

[0004] This invention utilizes gas-filled hollow optical fiber as a gain medium to generate mid-infrared laser.

[0005] The technical solution adopted in this invention is a high-power mid-infrared nanosecond pulsed hollow fiber gas laser, with a pump source of 2μm band single-frequency fiber laser, and the pump light is output to the lens through the fiber.

[0006] The lens includes a plano-convex lens connected in the primary optical path. Mirror Mirror Plano-convex lens The pump light is focused; gas chamber A is used to load the hollow anti-resonant fiber and fill it with gas at a pressure of 5.2 mbar. The focused pump light is coupled into the hollow anti-resonant fiber through a window. The hollow anti-resonant fiber is 6.8 m long and consists of eight quartz tubular cladding elements. Gas chamber B is used to load the hollow anti-resonant fiber and seal it with gas. A mid-infrared bandpass filter is placed at the end of the hollow fiber to filter out residual pump light in the 2 μm band and transmit signal light in the 4.3 μm band. At a pump laser power of 125 W and a carbon dioxide gas pressure of 5.2 mbar, a pulse output with a repetition frequency of 10 MHz and a pulse width of 29 ns at a wavelength of 4.3 μm is obtained, with a pulse energy of 1.027 μJ and a maximum output power of approximately 10.27 W. High-power laser output in the 4.3 μm band is achieved by filling the hollow fiber with carbon dioxide as a gain medium and using a mid-infrared laser as the pump source.

[0007] Furthermore, the center wavelength of the pump light is precisely tuned in the range of 1999.5~2001.6nm, with a repetition frequency of 10MHz, a pulse width of 37ns, and an output power of 140W.

[0008] Furthermore, the plano-convex lens With a focal length of 20mm, the pump light passes through a plano-convex lens. Perform alignment.

[0009] Furthermore, the reflector In the 1908nm to 2000nm wavelength range, the reflectivity is greater than 95%, and the collimated pump light is reflected to a mirror in another direction. .

[0010] Furthermore, the reflector With a reflectivity greater than 95% in the 1908nm to 2000nm wavelength range, the collimated pump light is reflected to a plano-convex lens in another direction. .

[0011] Furthermore, the plano-convex lens The focal length is 80mm, and the pump light passes through a plano-convex lens. Focus.

[0012] Furthermore, the gas chamber A has a window at the input port, wherein the input window is an anti-reflective coating window in the 2-micron band (with a transmittance of 98% in the range of 1.9-2.1μm).

[0013] Furthermore, gas chamber B has a window at the output port, wherein the output window is an uncoated calcium fluoride window (with a transmittance of 92% in the range of 1-5 μm).

[0014] Compared with existing technologies, this invention combines the advantages of hollow-core optical fibers and traditional gas lasers, featuring rich emission wavelengths, high output power, and good beam quality. The mid-infrared 3-5µm band falls within the "molecular fingerprint region," the high-transmittance "window" of the Earth's atmosphere, and the sensitive band of military detectors. Lasers in this band have important applications in military optoelectronic countermeasures, laser medicine, and trace gas detection.

[0015] A 10-watt, 4.3-μm nanosecond pulsed laser source was first obtained in a carbon dioxide-filled hollow optical fiber based on the population inversion mechanism between the vibrational and rotational energy levels of gas molecules.

[0016] Gas-filled hollow fiber lasers based on the population inversion principle use pump lasers to excite molecules from the ground state to the upper energy level vibrational state, resulting in population inversion between the upper and lower energy levels. When molecules radiatively transition from the upper energy level to the lower energy level, mid-infrared laser light is generated. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the device of the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] The present invention utilizes a gas-filled hollow optical fiber as a gain medium to generate mid-infrared laser. This invention combines the advantages of both hollow optical fibers and traditional gas lasers, featuring a rich range of emission wavelengths, high output power, and excellent beam quality. The mid-infrared 3–5 µm band falls within the "molecular fingerprint region," the high-transmittance "window" of the Earth's atmosphere, and is a sensitive band for military detectors. Lasers in this band have important applications in military optoelectronic warfare, laser medicine, and trace gas detection.

[0020] A 10-watt, 4.3-μm nanosecond pulsed laser source was first obtained in a carbon dioxide-filled hollow optical fiber based on the population inversion mechanism between the vibrational and rotational energy levels of gas molecules.

[0021] Gas-filled hollow fiber lasers based on the population inversion principle use pump lasers to excite molecules from the ground state to the upper energy level vibrational state, resulting in population inversion between the upper and lower energy levels. When molecules radiatively transition from the upper energy level to the lower energy level, mid-infrared laser light is generated.

[0022] Figure 1 This is a schematic diagram of the device of the present invention. The experimental setup for the carbon dioxide-filled hollow-core anti-resonant fiber optic light source consists of the following components:

[0023] Pump source 1: 2μm band single-frequency fiber laser, whose center wavelength can be precisely tuned in the range of 1999.5~2001.6nm, with a repetition frequency of 10MHz, a pulse width of 37ns, and an output power of 140W. The pump light is output to the lens through an optical fiber.

[0024] Plano-convex lens 2: The focal length is 20mm, and the pump light is collimated through this lens.

[0025] reflector 3: In the 1908nm to 2000nm band, the reflectivity is greater than 95%, and the collimated pump light is reflected in another direction.

[0026] reflector 4: In the 1908nm to 2000nm band, the reflectivity is greater than 95%, and the collimated pump light is reflected in another direction.

[0027] Plano-convex lens 5: The focal length is 80mm, and the pump light is focused through this lens.

[0028] Gas chamber A6: Used to load the hollow-core antiresonant fiber and fill it with gas at a pressure of 5.2 mbar. Gas chamber A has a window at its input port, which is an anti-reflective coated window in the 2-micron wavelength range (98% transmittance in the 1.9-2.1 μm range). The focused pump light is coupled into the hollow-core antiresonant fiber 7 through the window.

[0029] The hollow-core anti-resonant fiber 7 is 6.8m long and consists of eight quartz tubular cladding elements. Its core diameter is 150μm, and its theoretical transmission losses are 0.3dB / km@2.0μm and 84dB / km@4.3μm, respectively.

[0030] Gas chamber B8: Used to load hollow anti-resonant optical fiber and seal the gas. Gas chamber B8 has a window at the output port, where the output window is an uncoated calcium fluoride window (with a transmittance of 92% in the range of 1-5μm).

[0031] Mid-infrared bandpass filter 9: The mid-infrared bandpass filter (Thorlabs FB4250-500) is placed at the end of the hollow fiber to filter out residual pump light in the 2μm band and transmit signal light in the 4.3μm band.

[0032] With a pump laser power of 125W and a carbon dioxide gas pressure of 5.2mbar, a pulse output with a repetition frequency of 10MHz and a pulse width of 29ns at a wavelength of 4.3μm was obtained, with a pulse energy of 1.027μJ and a maximum output power of approximately 10.27W.

[0033] Carbon dioxide is filled into hollow optical fibers as a gain medium, and mid-infrared laser is used as a pump source to achieve high-power 4.3μm band laser output.

Claims

1. A high-power mid-infrared nanosecond pulsed hollow-core fiber gas laser, characterized in that: The pump source is a 2μm band single-frequency fiber laser, and the pump light is output to the lens through the fiber. The lens includes a plano-convex lens connected in the primary optical path. Mirror Mirror Plano-convex lens The pump light is focused; gas chamber A is used to load the hollow anti-resonant fiber and fill it with gas at a pressure of 5.2 mbar; the focused pump light is coupled into the hollow anti-resonant fiber through a window; the hollow anti-resonant fiber is 6.8 m long and consists of eight quartz tubular cladding elements; gas chamber B is used to load the hollow anti-resonant fiber and seal it with gas; a mid-infrared bandpass filter is placed at the end of the hollow fiber to filter out residual pump light in the 2 μm band and transmit signal light in the 4.3 μm band; at a pump laser power of 125 W and a carbon dioxide gas pressure of 5.2 mbar, a pulse output with a repetition frequency of 10 MHz and a pulse width of 29 ns at a wavelength of 4.3 μm is obtained, with a pulse energy of 1.027 μJ and a maximum output power of approximately 10.27 W; carbon dioxide is filled into the hollow fiber as a gain medium, and a mid-infrared laser is used as the pump source to achieve high-power laser output in the 4.3 μm band.

2. A high-power mid-infrared nanosecond pulsed hollow-core fiber gas laser according to claim 1, characterized in that: The center wavelength of the pump light is precisely tuned in the range of 1999.5~2001.6nm, with a repetition frequency of 10MHz, a pulse width of 37ns, and an output power of 140W.

3. A high-power mid-infrared nanosecond pulsed hollow fiber gas laser according to claim 1, characterized in that: The plano-convex lens With a focal length of 20mm, the pump light passes through a plano-convex lens. Perform alignment.

4. A high-power mid-infrared nanosecond pulsed hollow-core fiber gas laser according to claim 1, characterized in that: The reflector In the 1908nm to 2000nm wavelength range, the reflectivity is greater than 95%, and the collimated pump light is reflected to a mirror in another direction. .

5. A high-power mid-infrared nanosecond pulsed hollow fiber gas laser according to claim 1, characterized in that: The reflector With a reflectivity greater than 95% in the 1908nm to 2000nm wavelength range, the collimated pump light is reflected to a plano-convex lens in another direction. .

6. A high-power mid-infrared nanosecond pulsed hollow fiber gas laser according to claim 1, characterized in that: The plano-convex lens The focal length is 80mm, and the pump light passes through a plano-convex lens. Focus.

7. A high-power mid-infrared nanosecond pulsed hollow-core fiber gas laser according to claim 1, characterized in that: Gas chamber A has a window at the input port, where the input window is an anti-reflective coating window in the 2-micron band.

8. A high-power mid-infrared nanosecond pulsed hollow fiber gas laser according to claim 1, characterized in that: Gas chamber B has a window at the output port, wherein the output window is an uncoated calcium fluoride window.

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