Nonlinear compression device based on ultrashort femtosecond pulses generated by a perforated endoscope

Abstract

This utility model relates to a nonlinear compression device based on an ultrashort femtosecond pulse generated by a perforated cavity mirror, belonging to the field of nonlinear compression devices. The device includes: a perforated cavity mirror with at least one through-hole at a specific position, diameter, and tilt angle, the through-hole ensuring that the incident direction of the input laser beam matches the self-reproducing mode, and the output beam is output in reverse through the same through-hole; a concave reflector coaxial with the perforated cavity mirror; and a nonlinear medium filling the space between the perforated cavity mirror and the concave reflector. The perforated cavity mirror, concave reflector, and nonlinear medium combine to form a multi-cavity laser cavity, where the laser beam undergoes multiple reflections between the perforated cavity mirror and the concave reflector to form a self-reproducing mode. This nonlinear compression device based on an ultrashort femtosecond pulse generated by a perforated cavity mirror effectively solves the problems of damage risk, space occupation, and adjustment difficulty existing in the prior art by introducing a perforated cavity mirror to replace the traditional reflector injection structure.

Description

Technical Field

[0001] This utility model relates to the field of nonlinear compression devices, and in particular to a nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated cavity mirror. Background Technology

[0002] Traditional multi-cavity pulse compressors are widely used in high-power laser pulse compression systems such as femtosecond lasers. A multi-cavity pulse compressor typically consists of two concave mirrors and injection / output optical elements. Its core principle is to achieve pulse compression by using a reflective optical path structure and multiple reflections to create a self-reproducing mode within the cavity. These pulse compressors are widely used in laser technology, optical experiments, and industrial laser systems, especially in applications requiring high precision and high power output. However, traditional multi-cavity pulse compressors have an increased risk of damage in practical applications. Specifically, in the design of traditional multi-cavity pulse compressors, the laser beam needs to enter and exit through an injection mirror in front of the cavity mirrors. This results in a smaller spot size on the mirror (the closer to the cavity center, the smaller the spot size). Under the influence of high-power lasers, the concentrated energy density of the spot is high, which easily leads to mirror damage, especially when using femtosecond laser pulses, where this high energy density issue is more pronounced. Summary of the Invention

[0003] Therefore, it is necessary to provide a nonlinear compression device based on a perforated endoscope that generates ultrashort femtosecond pulses to address the increased risk of damage in practical applications of traditional multi-cavity pulse compressors.

[0004] This utility model provides a nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope, comprising:

[0005] A perforated cavity mirror has at least one through hole with a specific position, aperture and tilt angle on its mirror surface. The through hole is used to ensure that the incident direction of the input laser beam matches the self-reproducing mode, and the output beam is output in reverse through the same through hole.

[0006] A concave reflecting mirror is coaxial with the perforated cavity mirror;

[0007] A nonlinear medium is filled between the perforated cavity mirror and the concave reflector.

[0008] The perforated cavity mirror, concave mirror, and nonlinear medium are combined to form a multi-cavity laser cavity, and the laser beam is reflected multiple times between the perforated cavity mirror and the concave mirror to form a self-reproducing mode.

[0009] In one embodiment, the diameter of the through hole is 3-6 mm, and the center of the through hole is located in the region 70%-90% away from the center of the punched endoscope.

[0010] In one embodiment, the radii of curvature of the perforated cavity mirror and the concave reflector are adapted to the cavity length and the number of reflections, the distance between the perforated cavity mirror and the concave reflector is adjusted according to the spot pattern, and the number of laser reflections between the perforated cavity mirror and the concave reflector is 8-60.

[0011] In one embodiment, a first chirped mirror and a second chirped mirror are disposed outside the multi-cavity laser cavity.

[0012] In one embodiment, a collimating lens is provided between the perforated endoscope and the second chirped mirror.

[0013] In one embodiment, the nonlinear medium is an inert gas, and the gas pressure inside the multi-cavity laser cavity is 1-5 bar.

[0014] The aforementioned nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated cavity mirror injects the laser beam into the cavity through a through-hole on the perforated cavity mirror. After multiple reflections, the beam is automatically output through the same through-hole. On the one hand, due to the matching of the laser beam with the self-reproducing mode within the multi-cavity laser cavity, the input and output paths of the laser are precisely controlled. Since the beam is input and output through only one through-hole, the use of inlet and outlet mirrors in traditional designs is avoided. The smaller spot size resulting from the closer proximity to the cavity center leads to higher energy density, thus greatly reducing the risk of damage. On the other hand, by eliminating the folded optical path used by inlet and outlet mirrors in traditional designs, the optical path is simpler, and the device occupies significantly less space, making it suitable for applications with limited space and compact requirements. At the same time, adjustment and operation become simpler, reducing the need for high-precision mechanical adjustments, lowering the difficulty of equipment debugging and maintenance, and significantly improving the stability and reliability of the system, making it suitable for high-power laser pulse applications. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a nonlinear compression device based on an ultrashort femtosecond pulse generated by a perforated endoscope in one embodiment.

[0017] Figure 2 This is a schematic diagram of a perforated endoscope structure in one embodiment;

[0018] Figure 3 This is a schematic diagram of the multi-cavity mode structure and input / output in one embodiment.

[0019] Figure label:

[0020] 100. Drilled cavity mirror; 110. Through hole; 200. Concave mirror; 300. Nonlinear medium; 400. Multi-cavity laser cavity; 500. First chirped mirror; 600. Second chirped mirror; 700. Collimating lens. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0022] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this specification are for illustrative purposes only and do not represent the only possible implementation.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0024] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature and the second feature are in indirect contact through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this specification belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0026] Traditional multi-cavity pulse compressors are widely used in high-power laser pulse compression systems such as femtosecond lasers. A multi-cavity pulse compressor typically consists of two concave mirrors and injection / output optical elements. Its core principle is to use a reflective optical path structure and multiple reflections to create a self-reproducing mode within the cavity, thereby achieving pulse compression. These pulse compressors are widely used in laser technology, optical experiments, and industrial laser systems, especially in applications requiring high precision and high power output. However, traditional multi-cavity pulse compressors have several problems and shortcomings in practical applications, as follows:

[0027] 1. Increased risk of damage: In the design of traditional multi-cavity pulse compressors, the laser beam needs to enter through an injection mirror in front of the cavity mirror, which results in a smaller spot size on the mirror (the closer to the center of the cavity, the smaller the spot size). Under the action of high-power laser, the energy density of the concentrated spot is high, which can easily cause mirror damage, especially when using femtosecond laser pulses, where this high energy density problem is more prominent.

[0028] The complex optical path structure and large space occupation: Due to the use of a reflective injection structure, folded optical paths are usually required for the input and output of the beam, which increases the complexity of the system and the space occupied. For laser systems that require a compact design, this complex optical path design not only increases the size of the device, but also hinders the integration and debugging of the device.

[0029] Attitude control issues for the import and export mirrors: In traditional multi-cavity pulse compressors, the attitude of the import and export mirrors requires precise control, which complicates the tooling system and increases the difficulty of system debugging. Precise attitude control also requires additional mechanical and optical adjustment equipment, which not only increases costs but also raises the difficulty of maintenance and operation.

[0030] The following is combined Figures 1-3 This invention describes a nonlinear compression device based on ultrashort femtosecond pulses generated by a perforated endoscope.

[0031] like Figure 1As shown, in one embodiment, a nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated cavity mirror includes a perforated cavity mirror 100, a concave mirror 200, and a nonlinear medium 300.

[0032] The mirror of the perforated cavity mirror 100 has at least one through hole 110 with a specific position, aperture and tilt angle. The through hole 110 is used to ensure that the incident direction of the input laser beam matches the self-reproducing mode, and the output beam is output in reverse through the same through hole 110.

[0033] The perforated cavity mirror 100 can be manufactured using a variety of optical materials, depending on the operating wavelength and power of the laser system. Suitable materials may include optical glass, single-crystal materials, or high-performance coating materials to ensure good light transmission and low optical loss.

[0034] The through hole 110 can be designed according to a specific cavity shape. The position and size of the through hole 110 on the drilling cavity mirror 100 can be determined. Through holes 110 of different sizes and positions can be designed according to the time width, power and application scenario of the laser pulse.

[0035] The concave reflector 200 and the perforated cavity mirror 100 are coaxial.

[0036] Nonlinear medium 300 is filled between the perforated cavity mirror 100 and the concave mirror 200.

[0037] The perforated cavity mirror 100, the concave mirror 200, and the nonlinear medium 300 are combined to form a multi-cavity laser cavity 400. The laser beam is reflected multiple times between the perforated cavity mirror 100 and the concave mirror 200 to form a self-reproducing mode.

[0038] This nonlinear compression device is applicable to multi-pass cavities with different cavity types and number of passes, and has strong adaptability and scalability. By adjusting the length and number of passes of the multi-pass laser cavity 400, pulse compression in different power and wavelength ranges can be achieved.

[0039] The specific working principle is as follows:

[0040] The femtosecond laser pulse output from the laser source (such as yttrium-doped fiber or solid-state laser) is focused by optical elements (such as beam expanders and focusing lenses) and enters the multi-cavity laser cavity 400 through the through hole 110 on the perforated cavity mirror 100. The position and size of the through hole 110 are precisely designed to ensure that the incident direction of the laser beam matches the optical mode within the multi-cavity laser cavity 400.

[0041] The laser beam propagates through multiple reflections within the multi-cavity laser cavity 400 via the perforated cavity mirror 100 and the concave reflector 200. During these multiple reflections, the laser mode within the multi-cavity laser cavity 400 remains consistent, achieving mode "self-reproduction".

[0042] After the Nth reflection, i.e. the last reflection, the beam will naturally exit through the through-hole 110 on the perforated cavity mirror 100 without the need for any other optical elements such as inlet and outlet mirrors. This design avoids the complexity and optical loss caused by mirrors or inlet / outlet optical paths in traditional designs.

[0043] Since the input and output paths of the beam are precisely controlled by the position of the through hole 110 of the perforated cavity mirror, this structure achieves automatic locking of the cavity length and self-reproducible mode, which facilitates precise control of the cavity length and thus ensures the quality of the laser beam output by the system.

[0044] This nonlinear compression device, based on ultrashort femtosecond pulse generation using a perforated cavity mirror 100, injects a laser beam into the cavity through a through-hole 110 on the perforated cavity mirror 100. After multiple reflections, the beam is automatically output through the same through-hole 110. On the one hand, due to the matching of the laser beam with the self-reproducing mode within the multi-cavity laser cavity 400, the input and output paths of the laser are precisely controlled. Since the beam is input and output through only one through-hole 110, the use of inlet and outlet mirrors in traditional designs is avoided. The smaller spot size resulting from the closer proximity to the cavity center leads to higher energy density, thus greatly reducing the risk of damage. On the other hand, by eliminating the folded optical path used by inlet and outlet mirrors in traditional designs, the optical path is simpler, and the device occupies significantly less space, making it suitable for applications with limited space and compact requirements. At the same time, adjustment and operation become simpler, reducing the need for high-precision mechanical adjustments, lowering the difficulty of equipment debugging and maintenance, and significantly improving the stability and reliability of the system, making it suitable for high-power laser pulse applications.

[0045] In this embodiment, the diameter of the through hole 110 is 3-6 mm, and the center of the through hole 110 is located in the 70%-90% range from the center of the perforated endoscope 100.

[0046] The aperture of the through hole 110 is designed according to the laser power and the number of cavity passes. Low-power laser applications are adapted to a 3-4mm aperture, while high-power laser applications are adapted to a 5-6mm aperture. The incident angle and the number of reflections are determined by coordinate calculation to ensure that the beam accurately returns to the small aperture output after the Nth reflection.

[0047] See Figure 2 This demonstrates the specific design of the through hole 110 on the perforated endoscope 100 and the precise location of the through hole 110. Figure 2 The content includes:

[0048] Position of through hole 110: The center position of through hole 110 is marked in the figure and compared with the incident path and output path of the laser beam.

[0049] Aperture and Dimensions: The diameter and design dimensions of the through-hole 110 are specified to ensure precise beam control and matching of the self-reproducing mode.

[0050] Beam incident and output path: The beam is injected into the multi-cavity laser cavity 400 through the through hole 110 on the perforated cavity mirror 100, and is automatically output through the same through hole 110 at the final output.

[0051] In this embodiment, the radii of curvature of the perforated cavity mirror 100 and the concave mirror 200 are adapted to the cavity length and the number of reflections. The distance between the perforated cavity mirror 100 and the concave mirror 200 is adjusted according to the spot pattern. The number of laser reflections between the perforated cavity mirror 100 and the concave mirror 200 is 8-60.

[0052] In this embodiment, a first chirped mirror 500 and a second chirped mirror 600 are disposed outside the multi-cavity laser cavity 400. The first chirped mirror 500 and the second chirped mirror 600 are used to compensate for the dispersion of the laser pulse and compress the pulse width to below 50 fs.

[0053] Through multiple reflections, the interaction between the laser pulse and the nonlinear medium 300 broadens the laser pulse spectrum. After chirp compensation, a shorter laser pulse can be obtained, effectively reducing the pulse duration and increasing the peak power of the beam. The pulse compression effect depends on the intensity of the nonlinear effect within the cavity and the effectiveness of dispersion compensation.

[0054] In this embodiment, a collimating lens 700 is provided between the punched cavity mirror 100 and the second chirped mirror 600. The collimating lens 700 is used to maintain the collimation of the beam transmission.

[0055] In this embodiment, the nonlinear medium 300 is an inert gas, and the gas pressure inside the multi-cavity laser cavity 400 is 1-5 bar.

[0056] The nonlinear medium gas is an inert gas such as argon, neon, or a mixture thereof.

[0057] Specific application examples are as follows:

[0058] Suppose we need to compress a femtosecond laser pulse with a wavelength of 1030 nm, a pulse width of 250 fs, and a single pulse energy of 100 µJ, with the goal of compressing the pulse width to within 50 fs and achieving an output energy of 92 µJ. The specific implementation method is as follows:

[0059] After the laser pulse is output from the yttrium-doped solid-state laser, the beam spot size is controlled by a beam expander or beam reducer, and then focused by a specific lens and injected into the multi-channel cavity along the through hole 110 of the perforated cavity mirror.

[0060] The multi-cavity design utilizes a perforated cavity mirror 100 with a curvature radius of 300mm and a concave reflector 200, resulting in a total of 56 reflections. Each mirror has 28 reflections, the cavity length is close to 600mm, and the total cavity length is 33 meters.

[0061] By adjusting the direction of the laser beam incident into the multi-pass cavity and the distance between the coaxial perforated cavity mirror 100 and the concave reflector 200 within the multi-pass cavity, the laser beam is accurately output through the perforated cavity mirror 100 after being reflected a total of 56 times within the multi-pass cavity.

[0062] Injecting a suitable inert gas (such as argon at 3.8 bar) into the cavity allows the laser pulse spectrum to support 40 fs. Then, using a suitable chirped mirror for chirp compensation, a 40 fs output pulse with stable energy output can be obtained.

[0063] See Figure 3 The image shows the light spot distribution on the perforated endoscope 100 and the concave mirror 200 inside the cavity, as well as the location of the hole on the perforated endoscope 100. Figure 3 The upper-middle image shows the light spot distribution on the perforated endoscope 100. The positions of numbers 0 and 56 in the image overlap, indicating the location of the hole on the perforated endoscope 100. Figure 3 The lower middle image shows the light spot distribution on the concave mirror 200.

[0064] Optical mode: Figure 3 The optical mode of the laser beam propagating within the multi-cavity laser chamber 400 is indicated, comprising 56 passes. Each lens has 28 passes. Specifically, 4.46mm diameter holes are drilled at positions numbered 0 and 56 for laser injection into and output from the multi-cavity chamber.

[0065] Self-reproducible mode: This means that the 56 light spots on the perforated cavity mirror 100 and the concave mirror 200 are all the same size, constrained by the radius of curvature and relative distance of the cavity mirrors. After the light beam inside the cavity is reflected multiple times by the mirrors, a self-reproducible mode is finally formed, which matches the position of the small hole, automatically realizing the output of the light beam.

[0066] This nonlinear compression device based on the generation of ultrashort femtosecond pulses using a perforated cavity mirror effectively solves the problems of damage risk, space occupation, and adjustment difficulty in the existing technology by introducing a perforated cavity mirror 100 to replace the traditional reflector injection structure. It provides a highly efficient, compact, and stable pulse compressor design. This technical solution can significantly improve the performance of the laser system, reduce the complexity of the system, and broaden the application prospects of laser technology in various fields.

[0067] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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.

[0068] The above-described embodiments are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

Claims

1. A nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope, characterized in that, include: A perforated cavity mirror has at least one through hole with a specific position, aperture and tilt angle on its mirror surface. The through hole is used to ensure that the incident direction of the input laser beam matches the self-reproducing mode, and the output beam is output in reverse through the same through hole. A concave reflecting mirror is coaxial with the perforated cavity mirror; A nonlinear medium is filled between the perforated cavity mirror and the concave reflector. The perforated cavity mirror, concave mirror, and nonlinear medium are combined to form a multi-cavity laser cavity, and the laser beam is reflected multiple times between the perforated cavity mirror and the concave mirror to form a self-reproducing mode.

2. The nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope according to claim 1, characterized in that, The diameter of the through hole is 3-6mm, and the center of the through hole is located in the 70%-90% range from the center of the drilling endoscope.

3. The nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope according to claim 2, characterized in that, The radius of curvature of the perforated cavity mirror and the concave reflector is adapted to the cavity length and the number of reflections. The distance between the perforated cavity mirror and the concave reflector is adjusted according to the spot pattern. The number of laser reflections between the perforated cavity mirror and the concave reflector is 8-60.

4. The nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope according to claim 3, characterized in that, The multi-cavity laser cavity is provided with a first chirped mirror and a second chirped mirror.

5. The nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope according to claim 4, characterized in that, A collimating lens is provided between the perforated cavity mirror and the second chirped mirror.

6. The nonlinear compression device based on ultrashort femtosecond pulse generation using a perforated endoscope according to any one of claims 1 to 5, characterized in that, The nonlinear medium is an inert gas, and the gas pressure inside the multi-cavity laser cavity is 1-5 bar.

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