Light path system based on gas-filled hollow-core optical fiber

Abstract

The invention discloses a light path system based on a gas-filled hollow-core optical fiber, and the system comprises a spectrum broadening device which comprises a first gas extraction chamber, a gas inlet chamber and a second gas extraction chamber, the first gas extraction chamber and the second gas extraction chamber are located at the two ends of the gas inlet chamber respectively, and the first gas extraction chamber and the gas inlet chamber are separated through a first sealing part; the second air exhaust chamber and the air inlet chamber are separated through a second sealing piece; the spectrum broadening device is internally provided with a hollow-core optical fiber and is provided with at least one through hole penetrating through the pipe wall of the hollow-core optical fiber, the two ends of the hollow-core optical fiber penetrate through the first sealing piece and the second sealing piece respectively so that the two ends of the hollow-core optical fiber can be communicated with the first air suction chamber and the second air suction chamber respectively, and the through hole is located in the air inlet chamber. The two ends of the hollow-core optical fiber are subjected to air exhaust, so that the ionization rate and the self-focusing effect generated when the laser is output after the spectrum of the inflated hollow-core optical fiber is broadened can be remarkably reduced, the requirement for improving the power input of the laser is met, and a light path system can bear higher laser monopulse energy compression.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of laser optics, in particular to an optical path system based on a gas-filled hollow-core fiber. BACKGROUND

[0002] With the wide application of femtosecond lasers in the fields of strong-field physics, ultrafast spectroscopy, femtosecond laser processing and time-resolved imaging, the demand for high peak power, extremely short pulse and good beam quality is increasing. In recent years, gas-filled hollow-core fiber (HCF) has attracted widespread attention as an efficient pulse post-compression method. Its optical path system can significantly compress the pulse width while maintaining high laser output energy.

[0003] The mainstream gas-filled HCF post-compression technology currently uses differential pumping. The device pumps gas at the front end of the HCF, and pumps gas at the rear end of the HCF. The optical path is as shown in Figure 1 The gas pressure at the rear end of the HCF is high. The strong ionization and self-focusing nonlinear effects that exist when high-intensity laser propagates in the gas will consume the energy of the laser and deteriorate the beam quality, which significantly increases the influence of nonlinear effects in the gas on the characteristics of the laser, and also causes excessive ionization to accumulate a large amount of subsequent uncompensated high-order dispersion and to lose laser energy. SUMMARY

[0004] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of protection of the claims.

[0005] The embodiment of the present application provides an optical path system based on a gas-filled hollow-core fiber, which can ensure a low ionization rate in the optical path system and improve the upper limit of the laser single-pulse energy that can be tolerated.

[0006] The embodiment of the present application provides an optical path system based on a gas-filled hollow-core fiber, which comprises: The spectral broadening device comprises a first gas pumping chamber, a gas inlet chamber and a second gas pumping chamber. The first gas pumping chamber and the second gas pumping chamber are respectively located at two ends of the gas inlet chamber. The first gas pumping chamber and the gas inlet chamber are separated by a first sealing member. The second gas pumping chamber and the gas inlet chamber are separated by a second sealing member. A hollow-core fiber is installed in the spectral broadening device. The hollow-core fiber has at least one through hole penetrating the wall of the hollow-core fiber. The two ends of the hollow-core fiber respectively pass through the first sealing member and the second sealing member, so that the two ends of the hollow-core fiber respectively communicate with the first gas pumping chamber and the second gas pumping chamber. The through hole is located in the gas inlet chamber. The dispersion compensation and compression device is used for outputting the laser after dispersion compensation of the spectral broadening device.

[0007] In some embodiments, the optical path system further comprises a first polarization device, a second polarization device and a first reflection device; The laser emitted by the laser passes through the first polarization device and enters the first pumping chamber, the laser emitted by the second pumping chamber passes through the second polarization device and the first reflection device and enters the second pumping chamber, and the laser emitted by the first pumping chamber passes through the first polarization device and is reflected to the output of the dispersion compensation compression device.

[0008] In some embodiments, the dispersion compensation compression device comprises a first chirped mirror, the first polarization device comprises a first polarizer, a first rotator, a first half-wave plate and a second polarizer, the first polarizer, the first rotator, the first half-wave plate and the second polarizer are arranged in sequence along the propagation path of the laser, and the first chirped mirror is used for dispersion compensation of the laser reflected by the second polarizer.

[0009] In some embodiments, the second polarization device comprises a quarter-wave plate, a second rotator, a second half-wave plate and a third polarizer, and the quarter-wave plate, the second rotator, the second half-wave plate, the third polarizer and the first reflection device are arranged in sequence along the propagation path of the laser.

[0010] In some embodiments, the second polarization device comprises a fourth polarizer, a third half-wave plate and a second chirped mirror, the fourth polarizer, the third half-wave plate and the second chirped mirror are arranged in sequence along the propagation path of the laser, and the laser output by the second chirped mirror is reflected by the first reflection device and returns to the second pumping chamber through the fourth polarizer.

[0011] In some embodiments, the optical path system further comprises a third polarization device, a light splitting device and a second reflection device, and the spectral broadening device and the second reflection device constitute a loop with the light splitting device as the starting point; The laser emitted by the laser passes through the third polarization device and the light splitting device and is divided into two beams, which propagate in opposite directions in the loop and return to the light splitting device to combine, and are reflected by the third polarization device to the dispersion compensation compression device for dispersion compensation.

[0012] In some embodiments, two spectral broadening devices are arranged in the loop, and the two beams of laser light split by the light splitting device return to the light splitting device to combine after passing through the two spectral broadening devices in opposite directions in sequence.

[0013] In some embodiments, quarter-wave plates are arranged at both ends of the spectral broadening device, and a fifth polarizer is further arranged between the two spectral broadening devices.

[0014] In some embodiments, the dispersion compensation compression device comprises a third chirped mirror, the third polarization device comprises a sixth polarizer, a third rotator and a fourth half-wave plate, the sixth polarizer, the third rotator, the fourth half-wave plate and the light splitting device are sequentially arranged along the propagation path of the laser, and the third chirped mirror is used for dispersion compensation of the laser reflected by the sixth polarizer.

[0015] In some embodiments, the dispersion compensation compression device comprises a fourth chirped mirror, the third polarization device comprises a pulse splitting loop, a fourth rotator and a fifth half-wave plate, the pulse splitting loop, the fourth rotator, the fifth half-wave plate and the light splitting device are sequentially arranged along the propagation path of the laser, and the fourth chirped mirror is used for dispersion compensation of the laser output by the pulse splitting loop.

[0016] The gas-filled hollow-core fiber-based optical system provided by the embodiments of the present application can significantly reduce the ionization rate and self-focusing effect of the laser after the laser is spectrally broadened by the gas-filled hollow-core fiber, and can meet the requirement of increasing the power input of the laser without reducing the compression ratio or even increasing the compression ratio, so that the optical system can withstand higher laser single-pulse energy compression.

[0017] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and achieved by the structure specifically pointed out in the specification, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings are intended to provide a further understanding of the technical solutions of the present application and constitute a part of the specification, and are used together with examples of the present application to explain the technical solutions of the present application, and do not constitute a limitation on the technical solutions of the present application.

[0019] Figure 1 is a structural schematic diagram of a prior art gas-filled hollow-core fiber-based optical system; Figure 2 is a structural schematic diagram of a gas-filled hollow-core fiber-based optical system provided by an embodiment of the present application; Figure 3 is a structural schematic diagram of a gas-filled hollow-core fiber-based optical system provided by an embodiment of the present application; Figure 4 is a structural schematic diagram of a gas-filled hollow-core fiber-based optical system provided by an embodiment of the present application; Figure 5 This is a schematic diagram of an optical path system based on gas-filled hollow fiber with two spectral broadening devices provided in one embodiment of this application; Figure 6 This is a schematic diagram of the structure of an optical path system based on gas-filled hollow fiber with a pulse-splitting loop provided in one embodiment of this application; Figure 7 for Figure 2 A schematic diagram of the structure of the medium spectral broadening device. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various implementations. Simultaneously, the steps or actions described in the method description can be rearranged or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various orders in the specification and drawings are merely for the clear description of a particular embodiment and do not imply a mandatory order, unless otherwise stated that a particular order must be followed.

[0021] In the description of this application, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0023] Ultrafast laser pulses, characterized by high peak power and ultrashort pulse widths, have wide applications in precision spectroscopy, femtosecond laser processing, nonlinear optics, biomedical imaging, and strong-field physics. To further enhance the performance of ultrafast lasers in these fields, post-compression techniques are typically employed to broaden the pulse spectrum, combined with dispersion compensation methods to achieve pulse compression, thereby obtaining shorter pulse widths (approaching or falling below several optical cycles) and higher peak power. Existing post-compression techniques include multi-plate, multi-pass cell (MPC), gas-filled HCF, and plasma filamentation. Gas-filled HCF, due to its large effective mode area, tunable dispersion and nonlinear parameters, wide applicable wavelength range (covering ultraviolet to near-mid-infrared), and relatively high damage threshold under high-energy conditions, has become one of the mainstream methods for broadening and compressing high-energy femtosecond pulses.

[0024] In existing post-compression technology applications, solid-state fibers, such as highly nonlinear fibers and photonic crystal fibers, have been widely used for spectral broadening and pulse compression. However, the material dispersion and nonlinear parameters of solid-state fibers are fixed, lacking degrees of freedom for adjustment. Furthermore, they are constrained by effects such as material damage threshold, stimulated Raman scattering, and excessive self-phase modulation, making it difficult to achieve high-quality broadband broadening and high-fidelity compression under high peak power conditions. This limits the application range of solid-state fibers in high-energy ultrafast laser processing.

[0025] To overcome the aforementioned problems, the gas-filled HCF (Hydrogen-Coated Fiber) scheme has emerged. HCF typically has a large effective mode area, which can significantly reduce nonlinear accumulation effects while maintaining fundamental mode transmission. Simultaneously, by filling the hollow fiber with gas, dispersion characteristics and nonlinear parameters can be adjusted over a wide range, enabling more flexible pulse shaping. Specifically, by filling the hollow fiber with inert gases such as helium, argon, or neon and adjusting their pressure, pulse broadening can be effectively achieved using effects such as self-phase modulation and soliton dynamics. The broadened pulse, under the action of a suitable dispersion compensation device, can be further compressed to near the few optical periods, thereby obtaining higher time resolution and peak power to meet the needs of attosecond science.

[0026] like Figure 1As shown, existing differential pumping methods involve pumping gas from the front end of the HCF (Hydraulic Fluorescent Fiber) and introducing gas from the rear end. This structure, due to the high gas pressure at the HCF output rear end, is prone to strong ionization and self-focusing, which consumes laser energy and degrades beam quality. For example, the self-focusing threshold of an 800nm ​​laser in fused silica is 2.4MW. To avoid damaging the output window and reduce the self-focusing effect at the window location, the laser output from the HCF rear end needs to travel a long distance through a gas-filled enclosed space. This reduces the peak intensity of the laser passing through the window. Therefore, the laser output from the HCF rear end needs to travel a long distance through a gas-filled enclosed space to expand the beam spot. This significantly increases the impact of nonlinear effects in the gas on the laser characteristics, and also leads to excessive ionization, accumulating a large amount of high-order dispersion that cannot be compensated for later, and further depleting laser energy.

[0027] Based on this, this application provides an optical path system based on gas-filled hollow fiber. The spectral broadening device differs from the traditional hollow fiber method of one-end gas intake and one-end gas extraction. It can extract gas from both ends of the hollow fiber, which can significantly reduce the ionization rate and self-focusing effect when the laser is output after spectral broadening through the gas-filled hollow fiber. The optical path system constructed based on this spectral broadening device can meet the requirements of increasing laser power input without reducing or even increasing the compression ratio, so that the optical path system can withstand higher laser single-pulse energy compression.

[0028] Reference Figures 2 to 6 , Figures 2 to 6 A schematic diagram of an optical path system based on gas-filled hollow optical fiber according to an embodiment of this application is shown. Figure 2 As shown, the optical path system based on gas-filled hollow optical fiber provided in this application embodiment includes: a spectral broadening device 200, comprising a first extraction chamber 210, an inlet chamber 220, and a second extraction chamber 230. The first extraction chamber 210 and the second extraction chamber 230 are respectively located at both ends of the inlet chamber 220. The first extraction chamber 210 and the inlet chamber 220 are separated by a first sealing member 240, and the second extraction chamber 230 and the inlet chamber 220 are separated by a second sealing member 250; the spectral broadening device 200... A hollow optical fiber 100 is installed inside the 0. The hollow optical fiber 100 has at least one through hole 110 that penetrates the tube wall of the hollow optical fiber 100. The two ends of the hollow optical fiber 100 pass through the first sealing member 240 and the second sealing member 250 respectively, so that the two ends of the hollow optical fiber 100 are connected to the first air extraction chamber 210 and the second air extraction chamber 230 respectively. The through hole 110 is located in the air inlet chamber 220. A dispersion compensation compression device 300 is used to perform dispersion compensation on the laser output by the spectral broadening device 200 before outputting it.

[0029] It is understood that the optical path system based on gas-filled hollow fiber in this embodiment of the application, by installing the hollow fiber 100 into the air inlet chamber 220 and sealing the hollow fiber 100 with the first sealing member 240 and the second sealing member 250, allows the gas in the air inlet chamber 220 to reach the first extraction chamber 210 and the second extraction chamber 230 through the through hole 110. Therefore, during use, the first extraction chamber 210 and the second extraction chamber 230 at both ends of the hollow fiber 100 can be simultaneously extracted, which can significantly reduce the ionization rate and self-focusing effect that occur when the laser is output after spectral broadening through the gas-filled hollow fiber 100. While ensuring high coupling efficiency and high stability, it also achieves controllable gas pressure distribution inside the hollow fiber 100.

[0030] Reference Figure 7 , Figure 7 A schematic diagram of the spectral broadening device in the aforementioned optical path system based on gas-filled hollow fiber is shown. Figure 7 As shown, the spectral broadening device 200 also includes an air inlet connector 221, a first air extraction connector 211, and a second air extraction connector 231. The air inlet connector 221 is disposed on the outer wall of the air inlet chamber 220, the first air extraction connector 211 is disposed on the outer wall of the first air extraction chamber 210, and the second air extraction connector 231 is disposed on the outer wall of the second air extraction chamber 230. This structure enables simultaneous air extraction at both ends of the hollow fiber 100 and air intake at the middle position, effectively maintaining a low air pressure at both ends of the hollow fiber 100. This avoids the influence of plasma defocusing regardless of which end the laser enters the hollow fiber 100 from, improving the efficiency of laser coupling to the hollow fiber 100.

[0031] In practical applications, the relationship between the peak power of a laser and its single-pulse energy is shown in the following formula:

[0032] in It is energy. It's a pulse width.

[0033] To ensure the transmittance of the hollow fiber 100 to the laser, excessive ionization and self-focusing must be avoided inside the hollow fiber 100. Based on these constraints, the scaling relationship between the peak power of the incident laser in the spectral broadening device 200 and the air pressure, inner diameter, and effective length can be obtained, as shown in the following formula:

[0034] in, It is the peak power of the incident laser. It's air pressure. It refers to the inner diameter of a 100mm hollow fiber. This is the effective length of the B integral. To improve peak power... Traditional methods use lower air pressure Increase inner diameter And increase the length of the hollow fiber 100. This application achieves peak power through optical path design in different embodiments. The improvement.

[0035] In some embodiments, the optical path system further includes a first polarization device 400, a second polarization device 500, and a first reflection device 600; the laser emitted by the laser 130 passes through the first polarization device 400 and enters the first evacuation chamber 210; the laser emitted from the second evacuation chamber 230 passes through the second polarization device 500 and the first reflection device 600 and enters back into the second evacuation chamber 230; the laser emitted from the first evacuation chamber 210 is reflected by the first polarization device 400 and output to the dispersion compensation compression device 300.

[0036] like Figure 2 As shown, the laser emitted by laser 130 enters the first polarization device 400 after passing through mirror 140. Mirror 140 is a broadband high-reflectivity mirror, but a silver film mirror can also be used. Afterward, the laser passes through the first polarization device 400 and enters the first extraction chamber 210, then passes through the second polarization device 500 and the first reflection device 600 before entering the second extraction chamber 230. Finally, it is reflected by the first polarization device 400 and output to the dispersion-compensating compressor 300.

[0037] Figure 2 The optical path design principle utilizes polarization optical elements to control the polarization of light, allowing each pulse to pass through the hollow fiber 100 twice. This controls the peak intensity of the laser input to be below the ionization threshold, effectively extending the accumulation of the B integral. .

[0038] In some embodiments, the dispersion compensation compression device 300 includes a first chirped mirror 310, and the first polarization device 400 includes a first polarizer 410, a first optical rotator 420, a first half-wave plate 430, and a second polarizer 440. The first polarizer 410, the first optical rotator 420, the first half-wave plate 430, and the second polarizer 440 are arranged sequentially along the propagation path of the laser. The first chirped mirror 310 is used to perform dispersion compensation on the laser reflected by the second polarizer 440.

[0039] Understandably, the dispersion compensation and compression device 300 consists of a chirp mirror (CM) or a pair of gratings. Specifically, the chirp mirror is a core optical element in an ultrafast laser system used to compensate for dispersion, compressing the laser pulse width by introducing a specific amount of dispersion. Through a multi-layer coating design, the chirp mirror introduces negative group delay dispersion when reflecting the light pulse, counteracting the positive dispersion generated when the laser propagates in the hollow fiber 100, thereby reducing pulse broadening.

[0040] like Figure 2 As shown, the first polarization device 400 includes a first polarizer 410, a first optical rotator 420, a first half-wave plate 430, and a second polarizer 440, which are arranged sequentially along the propagation path of the laser.

[0041] The first polarizer 410 and the second polarizer 440 are thin film polarizers (TFPs). A TFP is an optical polarizer based on a multilayer dielectric coating. When laser light is incident on a TFP, due to the anisotropy of the refractive index of the film material, the propagation speed of the light in the perpendicular and parallel directions is different. The perpendicular and parallel components undergo multiple reflections and interferences at the interfaces of the film layers, ultimately resulting in the effective suppression of one polarization component and the enhancement of the other polarization component, thereby generating linearly polarized light. The first optical rotator 420 is a Faraday rotator (FR). An FR is an optical device that uses the Faraday effect to rotate the polarization state of light. It consists of a magneto-optical crystal and a permanent magnet or ferromagnetic material that generates a magnetic field. When linearly polarized light passes through a transparent medium in a magnetic field, its polarization direction will rotate. The first half-wave plate 430 (HWP) is made of a quartz birefringent crystal with a precise thickness. Its optical axis is parallel to the surface of the crystal. The HWP can generate an optical path difference of half a wavelength, or 180° phase difference, between two mutually perpendicular linearly polarized lights, thereby changing the polarization state of the light.

[0042] In some embodiments, the second polarization device 500 includes a quarter-wave plate 510, a second optical rotator 520, a second half-wave plate 530, and a third polarizer 540, which are arranged sequentially along the propagation path of the laser.

[0043] like Figure 2 As shown, a quarter-wave plate 510, a second optical rotator 520, a second half-wave plate 530, a third polarizer 540, and a first reflecting device 600 are arranged sequentially along the laser propagation path. The quarter-wave plate 510 (QWP) is used to change the polarization state of the light. A QWP is typically made of a birefringent material; when light is incident perpendicularly, it decomposes the incident light into ordinary and extraordinary light, creating a quarter-wavelength (90° phase difference) optical path difference between them. After passing through the second polarizer 500, the laser returns along its original path after passing through the first reflecting device 600.

[0044] In some embodiments, the second polarization device 500 includes a fourth polarizer 550, a third half-wave plate 560, and a second chirped mirror 570. The fourth polarizer 550, the third half-wave plate 560, and the second chirped mirror 570 are arranged sequentially along the propagation path of the laser. The laser output from the second chirped mirror 570 is reflected by the first reflecting device 600 and returns to the second extraction chamber 230 after passing through the fourth polarizer 550.

[0045] In some embodiments, lenses 260 are provided on both sides of the spectral broadening device 200. Lenses 260 can collimate incident divergent light (such as a Gaussian beam output from a laser) into parallel light, or focus parallel light into focused light, enabling the beam to accurately enter the core region of the hollow fiber 100 and reducing light leakage loss during coupling. In other embodiments, lenses 260 can be replaced with concave silver mirrors.

[0046] Reference Figure 3 , Figure 3 This is a schematic diagram of an optical path system based on gas-filled hollow optical fiber, equipped with a second chirped mirror 570, according to one embodiment of this application. Figure 3 As shown, the fourth polarizer 550, the third half-wave plate 560, and the second chirped mirror 570 are arranged sequentially along the laser propagation path. The laser output from the second chirped mirror 570 is reflected by the first reflecting device 600 and returns to the second extraction chamber 230 after passing through the fourth polarizer 550. At this time, the first reflecting device 600 can also be composed of three reflecting mirrors 140. After the laser output from the second chirped mirror 570 passes through the three reflecting mirrors 140 in sequence, the laser angle changes by 270° and re-enters the fourth polarizer 550. After adjusting the angle, it enters the second extraction chamber 230 in the opposite direction of the original optical path.

[0047] It should be noted that, Figure 3 optical path and Figure 2 The difference in optical paths lies in Figure 3 The design allows the laser pulse to undergo spectral broadening once through the hollow fiber 100, and then directly use the second chirped mirror 570 to compensate for dispersion. After pulse compression, it is coupled back into the hollow fiber 100 for further spectral broadening. Under suitable air pressure distribution conditions, this is beneficial for accumulating more B integrals, making it suitable for laser compression with a few cycles.

[0048] Reference Figure 4 , Figure 4 This is a schematic diagram of an optical path system based on gas-filled hollow optical fiber, equipped with a beam splitter 800, according to an embodiment of this application. Figure 4As shown, in some embodiments, the optical path system further includes a third polarization device 700, a beam splitter 800, and a second reflection device 900. The spectral broadening device 200 and the second reflection device 900 form a loop starting from the beam splitter 800. The laser emitted by the laser 130 is split into two beams after passing through the third polarization device 700 and the beam splitter 800. They propagate in opposite directions in the loop and return to the beam splitter 800 to be combined. The beams are then reflected by the third polarization device 700 to the dispersion compensation and compression device 300 for dispersion compensation.

[0049] It should be noted that the laser emitted by laser 130 is split into two beams after passing through the third polarization device 700 and the beam splitter 800. These beams propagate in opposite directions within the loop and return to the beam splitter 800 to be combined, forming a Sagnac Ring. The core of the Sagnac Ring is that the same beam is split and propagates in two opposite directions along the ring's optical path. After completing one revolution, the two beams rejoin. If the ring structure does not rotate, the two beams have the same optical path length and no phase difference. The beam splitter 800 can utilize a telephoto lens (TFP) to achieve both beam splitting and combining.

[0050] like Figure 4 The optical path design shown allows a single laser beam to be split into two beams by a beam splitter 800. Each beam then undergoes spectral broadening via a hollow fiber 100 before being combined again by the beam splitter 800. This structure effectively increases the peak power that a single hollow fiber 100 can withstand. .

[0051] In some embodiments, two spectral broadening devices 200 are provided in the loop. The two laser beams split by the beam splitter 800 pass through the two spectral broadening devices 200 in opposite directions and then return to the beam splitter 800 for beam recombination.

[0052] Reference Figure 5 , Figure 5 This is a schematic diagram of an optical path system based on gas-filled hollow fiber, equipped with two spectral broadening devices 200, according to an embodiment of this application. Figure 5 As shown, a spectral broadening device 200 is provided on both sides of the Sagnac ring. The two laser beams split from the beam splitter 800 pass through the two spectral broadening devices 200 in opposite directions before returning to the beam splitter 800 for recombining. The process of the laser passing through the two spectral broadening devices 200 is the same as the steps described above, and will not be repeated here.

[0053] In some embodiments, quarter-wave plates 510 are respectively provided at both ends of the spectral broadening device 200, and a fifth polarizer 270 is also provided between the two spectral broadening devices 200.

[0054] It should be noted that by setting quarter-wave plates 510 at both ends of the spectral broadening device 200, the laser pulses entering the hollow fiber 100 can be circularly polarized, reducing the nonlinearity and ionization rate of the gas inside the hollow fiber 100, thereby increasing the single-pulse energy that the optical path system based on gas-filled hollow fiber can withstand.

[0055] It should be noted that, as Figure 5 and Figure 6 As shown, if the polarization states of the clockwise (CW) and counterclockwise (CCW) beams in the Sagnac ring are inconsistent, some power will be transmitted along the direction of the red arrow on the left side of the beam splitter 800 during beam combining. Therefore, by setting the fifth polarizer 270, the P-polarized component of the two beams can be filtered out, reducing the output power of the laser along the direction of the red arrow after passing through the beam splitter 800, effectively reducing power leakage after passing through the beam splitter 800.

[0056] Figure 5 The structure enables passive coherent combining of optical paths; this optical path design is based on... Figure 2 Based on this, each pulse passes through an additional air-filled hollow fiber 100, accumulating more B integrals, which is suitable for applications that further compress pulses.

[0057] In some embodiments, the dispersion compensation compression device 300 includes a third chirped mirror 320, and the third polarization device 700 includes a sixth polarizer 710, a third optical rotator 720, and a fourth half-wave plate 730. The sixth polarizer 710, the third optical rotator 720, the fourth half-wave plate 730, and the beam splitter 800 are arranged sequentially along the propagation path of the laser. The third chirped mirror 320 is used to perform dispersion compensation on the laser reflected by the sixth polarizer 710.

[0058] like Figure 4 and Figure 5 As shown, the sixth polarizer 710, the third optical rotator 720, the fourth half-wave plate 730, and the beam splitter 800 are arranged sequentially along the laser propagation path. The third chirped mirror 320 is used to compensate for the dispersion of the laser reflected by the sixth polarizer 710. The functions of the sixth polarizer 710, the third optical rotator 720, and the fourth half-wave plate 730 are the same as those of the first polarizer 410, the first optical rotator 420, and the first half-wave plate 430 in the above embodiment. The function of the third chirped mirror 320 is the same as that of the first chirped mirror 310 in the above embodiment, and will not be repeated here. The difference is that the first chirped mirror 310 is used to compensate for the dispersion of the laser passing through the second polarizer 440, while the third chirped mirror 320 is used to compensate for the dispersion of the laser passing through the fourth half-wave plate 730, the third optical rotator 720, and the sixth polarizer 710.

[0059] Reference Figure 6 ,Figure 6 This is a schematic diagram of an optical path system based on gas-filled hollow fiber, equipped with a pulse-splitting loop 740, according to an embodiment of this application. Figure 6 As shown, the dispersion compensation and compression device 300 includes a fourth chirped mirror 330, and the third polarization device 700 includes a pulse splitting loop 740, a fourth optical rotator 750, and a fifth half-wave plate 760. The pulse splitting loop 740, the fourth optical rotator 750, the fifth half-wave plate 760, and the beam splitting device 800 are arranged sequentially along the propagation path of the laser. The fourth chirped mirror 330 is used to perform dispersion compensation on the laser output from the pulse splitting loop 740.

[0060] like Figure 6 As shown, the pulse-splitting loop 740 coherently segments the pulse before the spectral broadening device 200, allowing the segmented sub-pulses to propagate along different paths and accumulate smaller nonlinear phase shifts. These sub-pulses are then recombined before output, effectively increasing the peak power that the entire device can withstand. Furthermore, by using the pulse-splitting loop 740, the pulse is segmented before the spectral broadening device 200, and the nonlinear spectral broadening process experienced by each sub-pulse is relatively independent. This allows each sub-pulse to withstand higher gas pressures during spectral broadening, thereby increasing the peak power that the optical path system can withstand without reducing the compression ratio.

[0061] Figure 6 The optical path design is based on Figure 5 Based on the optical path design, a pulse-splitting loop 740 is added, which divides a pulse into two in time. This further reduces the single-pulse energy of each pulse passing through the hollow fiber 100, thereby increasing the peak power of the input light. The ultimate effect is to enable optical systems based on gas-filled hollow optical fibers to withstand higher laser single-pulse energy compression.

[0062] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0063] It will be understood by those skilled in the art that all or some of the steps and systems in the methods disclosed above can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all of the physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0064] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An optical path system based on gas-filled hollow optical fiber, characterized in that, include: A spectral broadening device 200 includes a first extraction chamber 210, an inlet chamber 220, and a second extraction chamber 230. The first extraction chamber 210 and the second extraction chamber 230 are located at opposite ends of the inlet chamber 220. The first extraction chamber 210 and the inlet chamber 220 are separated by a first sealing member 240, and the second extraction chamber 230 and the inlet chamber 220 are separated by a second sealing member 250. A hollow optical fiber 100 is installed inside the spectral broadening device 200. The hollow optical fiber 100 has at least one through hole 110 penetrating the tube wall of the hollow optical fiber 100. The two ends of the hollow optical fiber 100 pass through the first sealing member 240 and the second sealing member 250, respectively, so that the two ends of the hollow optical fiber 100 are connected to the first extraction chamber 210 and the second extraction chamber 230, respectively. The through hole 110 is located in the inlet chamber 220. The dispersion compensation compression device 300 is used to perform dispersion compensation on the laser output from the spectral broadening device 200 before outputting it.

2. The optical path system according to claim 1, characterized in that, The optical path system also includes a first polarization device 400, a second polarization device 500, and a first reflection device 600; The laser emitted by the laser 130 passes through the first polarization device 400 and enters the first extraction chamber 210. The laser emitted from the second extraction chamber 230 passes through the second polarization device 500 and the first reflection device 600 and enters back into the second extraction chamber 230. The laser emitted from the first extraction chamber 210 is reflected by the first polarization device 400 and output by the dispersion compensation compression device 300.

3. The optical path system according to claim 2, characterized in that, The dispersion compensation and compression device 300 includes a first chirped mirror 310, and the first polarization device 400 includes a first polarizer 410, a first optical rotator 420, a first half-wave plate 430, and a second polarizer 440. The first polarizer 410, the first optical rotator 420, the first half-wave plate 430, and the second polarizer 440 are arranged sequentially along the propagation path of the laser. The first chirped mirror 310 is used to perform dispersion compensation on the laser reflected by the second polarizer 440.

4. The optical path system according to claim 3, characterized in that, The second polarization device 500 includes a quarter-wave plate 510, a second optical rotator 520, a second half-wave plate 530, and a third polarizer 540, wherein the quarter-wave plate 510, the second optical rotator 520, the second half-wave plate 530, the third polarizer 540, and the first reflection device 600 are arranged sequentially along the propagation path of the laser.

5. The optical path system according to claim 3, characterized in that, The second polarization device 500 includes a fourth polarizer 550, a third half-wave plate 560, and a second chirped mirror 570. The fourth polarizer 550, the third half-wave plate 560, and the second chirped mirror 570 are arranged sequentially along the propagation path of the laser. The laser output by the second chirped mirror 570 is reflected by the first reflecting device 600 and returns to the second extraction chamber 230 after passing through the fourth polarizer 550.

6. The optical path system according to claim 1, characterized in that, The optical path system also includes a third polarization device 700, a beam splitter 800, and a second reflection device 900. The spectral broadening device 200 and the second reflection device 900 form a loop starting from the beam splitter 800. The laser emitted by the laser 130 is split into two beams after passing through the third polarization device 700 and the beam splitter 800. The beams propagate in opposite directions in the loop and return to the beam splitter 800 to be combined. The beams are then reflected by the third polarization device 700 to the dispersion compensation and compression device 300 for dispersion compensation.

7. The optical path system according to claim 6, characterized in that, Two spectral broadening devices 200 are provided in the loop. The two laser beams split by the beam splitter 800 pass through the two spectral broadening devices 200 in opposite directions and then return to the beam splitter 800 to be combined.

8. The optical path system according to claim 7, characterized in that, A quarter-wave plate 510 is provided at each end of the spectral broadening device 200, and a fifth polarizer 270 is provided between the two spectral broadening devices 200.

9. The optical path system according to claim 6, characterized in that, The dispersion compensation and compression device 300 includes a third chirped mirror 320, and the third polarization device 700 includes a sixth polarizer 710, a third optical rotator 720, and a fourth half-wave plate 730. The sixth polarizer 710, the third optical rotator 720, the fourth half-wave plate 730, and the beam splitter 800 are arranged sequentially along the propagation path of the laser. The third chirped mirror 320 is used to perform dispersion compensation on the laser reflected by the sixth polarizer 710.

10. The optical path system according to claim 6, characterized in that, The dispersion compensation and compression device 300 includes a fourth chirped mirror 330, and the third polarization device 700 includes a pulse splitting loop 740, a fourth optical rotator 750, and a fifth half-wave plate 760. The pulse splitting loop 740, the fourth optical rotator 750, the fifth half-wave plate 760, and the beam splitting device 800 are arranged sequentially along the propagation path of the laser. The fourth chirped mirror 330 is used to perform dispersion compensation on the laser output by the pulse splitting loop 740.

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