A pulse compressor with ease of adjustment

Abstract

The present application relates to pulse compressor, specifically to a kind of pulse compressor of being adjusted easily, including collimating lens, first plane mirror, first diffraction grating, corner cube reflector, high-low mirror and second plane mirror, the surface of collimating lens and the input light port of pulse compressor panel are all equipped with pinhole diaphragm, first plane mirror is fixedly installed on precision rotary table, corner cube reflector is fixedly installed on precision displacement table;The technical scheme provided by the present application can effectively overcome the defects that the negative dispersion value introduced by changing the relative interval of grating and the diffraction angle of grating is not convenient to adjust to obtain different pulse width compression, and it is inconvenient to collimate and adjust incident light.

Description

Technical Field

[0001] This invention relates to pulse compressors, and more specifically to an easily adjustable pulse compressor. Background Technology

[0002] Femtosecond lasers, with their extremely high peak power and extremely narrow pulse width, have been widely used in fields such as precision micromachining of materials, semiconductors, and solar photovoltaics. When used for materials processing, femtosecond lasers interact with matter using extremely short-duration light pulses, injecting all their energy into a very small area of ​​interaction at an extremely high speed. The thermal effects on the material are well controlled. Compared to nanosecond and picosecond lasers, femtosecond lasers offer advantages such as high precision, a small heat-affected zone, and burr-free processing edges.

[0003] Chirped pulse amplification (CPA) is widely used in ultrashort pulse fiber lasers. Its principle is to first broaden the ultrashort optical pulse in the time domain, then amplify it to high energy, and finally compress the pulse width back. This technique effectively reduces the peak power of the pulse in the amplifier and gets rid of the limitation of nonlinear effects. High peak power ultrashort pulses can be obtained from this laser system.

[0004] Laser pulse compression is generally achieved using grating-pair compressors. The working principle of a grating-pair compressor is as follows: when a positively chirped pulse passes through a parallel grating, it experiences different optical paths for different spectral components. The optical path experienced by a longer wavelength is greater than that of a shorter wavelength. By introducing a negative dispersion compensation positive chirp conjugate with the stretcher, pulse compression is achieved.

[0005] Currently, the pulse width compression of pulse compressors is achieved by adjusting the introduced negative dispersion value by changing the relative spacing and diffraction angle of the gratings. To obtain different pulse width compression values, the relative distance and diffraction angle of the gratings in the pulse compressor need to be adjustable, and the grating pairs must be placed in strict parallel alignment. Therefore, the adjustment of the angle places very high demands on the rotational accuracy of the rotary stage. At the same time, as an independent and integrable module, the pulse compressor requires collimation of the angle and height of the incident light. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention provides an easily adjustable pulse compressor, which can effectively overcome the defects of the prior art, such as the inconvenience of adjusting the negative dispersion value introduced by changing the relative spacing of the grating and the diffraction angle of the grating to obtain different pulse width compression amounts, and the inconvenience of collimating the incident light.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] An easily adjustable pulse compressor includes a collimating lens, a first plane mirror, a first diffraction grating, a corner mirror, an elevation mirror, and a second plane mirror. The collimating lens and the input port of the pulse compressor panel are both provided with pinhole apertures. The first plane mirror is fixedly mounted on a precision rotating stage, and the corner mirror is fixedly mounted on a precision displacement stage.

[0011] Collimating lens, incident light enters the pinhole aperture through the collimating lens;

[0012] A pinhole aperture is used to direct the collimated incident light onto the first plane mirror.

[0013] The first plane mirror receives the collimated incident light and reflects it to form a first incident beam that is incident on the first diffraction grating; it also receives the fourth diffraction beam generated by the first diffraction grating and reflects it to form a pulse-width compressed beam that is incident on the output port of the pulse compressor panel.

[0014] The first diffraction grating receives the first incident beam generated by the first plane mirror and undergoes a first diffraction to form a first diffracted beam and a 0th-order beam; it receives the second incident beam generated by the corner mirror and undergoes a second diffraction to form a second diffracted beam; it receives the third incident beam generated by the high and low mirrors and undergoes a third diffraction to form a third diffracted beam; it then receives the fourth incident beam generated by the corner mirror again and undergoes a fourth diffraction to form a fourth diffracted beam.

[0015] The corner mirror receives the first diffracted beam generated by the first diffraction grating and reflects it to form a second incident beam that is incident on the first diffraction grating; it also receives the third diffracted beam generated by the first diffraction grating and reflects it to form a fourth incident beam that is incident on the first diffraction grating.

[0016] The high-low mirror receives the first diffraction beam generated by the first diffraction grating and elevates the light to a certain height to form a third incident beam that is incident on the first diffraction grating.

[0017] The second planar reflector receives the zero-order light generated by the first diffraction grating and reflects the zero-order light to the reference light output port of the pulse compressor panel.

[0018] Preferably, the first diffraction grating is a transmission grating or a reflection grating, and the grating lines of the first diffraction grating are in the vertical direction.

[0019] Preferably, the corner mirror consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the vertical direction.

[0020] Preferably, the elevation mirror consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the horizontal direction.

[0021] Preferably, the panel of the pulse compressor includes an input optical port, an output optical port, a reference optical output port, a dispersion adjustment and dispersion display window;

[0022] The dispersion adjustment is used to electrically or manually adjust the precision rotary stage and the precision displacement stage. The angle of the first incident beam is adjusted by controlling the angle of the first plane mirror through the precision rotary stage, so as to change the introduced negative second-order dispersion value. The distance between the corner mirror and the first diffraction grating is controlled by the precision displacement stage to change the introduced negative second-order dispersion value.

[0023] Preferably, the reference light output port is provided with a crosshair, and a detection camera connected to an external computer is provided at the reference light output port. The incident light collimation is adjusted by observing the position of the zero-order light output in real time. When the zero-order light reflected from the second plane mirror is located at the center of the crosshair, the incident light collimation is completed.

[0024] Preferably, when monochromatic light is incident on the surface of the diffraction grating at an incident angle γ, the light is diffracted and deflected, and the diffraction angle γ-θ of the diffracted light changes with the wavelength:

[0025] sinγ+sin(γ-θ)=λ / d;

[0026] Where λ is the wavelength of the incident light, d is the spacing between the grating lines, and θ is the angle between the incident light and the diffracted light;

[0027] The relationship between the grating pair spacing G and the geometric path P of the beam between the grating pairs is as follows:

[0028]

[0029] The negative second-order dispersion φ introduced by the grating pair is:

[0030]

[0031] Where c is the speed of light;

[0032] The output pulse width after introducing the negative second-order dispersion φ” is:

[0033]

[0034] Where, τ in τ is the input pulse width. out The output pulse width;

[0035] According to the above formula, given the diffraction angle γ-θ of the diffracted light and the grating pair spacing G, the negative second-order dispersion φ” and the pulse width compression can be calculated and displayed in real time in the dispersion display window of the pulse compressor panel.

[0036] (III) Beneficial Effects

[0037] Compared with the prior art, the pulse compressor provided by the present invention is easy to adjust. The angle of the first incident beam is adjusted by controlling the angle of the first plane mirror through a precision rotary stage, and the distance between the corner mirror and the first diffraction grating is controlled by a precision displacement stage to change the introduced negative second-order dispersion value, thereby making it very convenient to obtain different pulse width compression amounts. The reference light output port is provided with a crosshair. When the 0th order light reflected from the second plane mirror is located at the center of the crosshair, the incident light collimation adjustment is completed, making the incident light collimation adjustment convenient and quick. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0039] Figure 1 This is a schematic diagram of the first structure of the present invention;

[0040] Figure 2 This is a schematic diagram of the second structure of the present invention;

[0041] Figure 3 This is a schematic diagram of the pulse compressor panel in this invention;

[0042] Figure 4 For the present invention Figure 3 A magnified schematic diagram of the reference light output port;

[0043] Figure 5 This is a schematic diagram of the dispersion of the grating. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0045] An easily adjustable pulse compressor, such as Figure 1 As shown, it includes a collimating lens 1, a first plane mirror 2, a first diffraction grating 4, a corner mirror 5, an elevation mirror 7, and a second plane mirror 8. The collimating lens 1 and the input light port of the pulse compressor panel are both provided with pinhole apertures 9. The first plane mirror 2 is fixedly installed on a precision rotary stage 3, and the corner mirror 5 is fixedly installed on a precision displacement stage 6.

[0046] Collimating lens 1, the incident light enters the pinhole aperture 9 through collimating lens 1;

[0047] The pinhole aperture 9 allows the collimated incident light to be incident on the first plane mirror 2;

[0048] The first plane mirror 2 receives the collimated incident light and reflects it to form a first incident beam that is incident on the first diffraction grating 4; it also receives the fourth diffraction beam generated by the first diffraction grating 4 and reflects it to form a pulse-width compressed beam that is incident on the output port of the pulse compressor panel.

[0049] The first diffraction grating 4 receives the first incident beam generated by the first plane mirror 2 and undergoes a first diffraction to form a first diffracted beam and a 0th order beam; it receives the second incident beam generated by the corner mirror 5 and undergoes a second diffraction to form a second diffracted beam; it receives the third incident beam generated by the high-low mirror 7 and undergoes a third diffraction to form a third diffracted beam; it then receives the fourth incident beam generated by the corner mirror 5 again and undergoes a fourth diffraction to form a fourth diffracted beam.

[0050] The corner mirror 5 receives the first diffracted beam generated by the first diffraction grating 4 and reflects it to form a second incident beam that is incident on the first diffraction grating 4; it also receives the third diffracted beam generated by the first diffraction grating 4 and reflects it to form a fourth incident beam that is incident on the first diffraction grating 4.

[0051] The high-low mirror 7 receives the first diffracted beam generated by the first diffraction grating 4 and raises the light to a certain height to form a third incident beam that is incident on the first diffraction grating 4.

[0052] The second plane mirror 8 receives the zero-order light generated by the first diffraction grating 4 and reflects the zero-order light to the reference light output port of the pulse compressor panel.

[0053] The first diffraction grating 4 is a transmission grating or a reflection grating, and the grating lines of the first diffraction grating 4 are in the vertical direction.

[0054] The corner mirror 5 consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the vertical direction.

[0055] The elevation mirror 7 consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the horizontal direction.

[0056] like Figure 3 As shown, the pulse compressor's panel includes an input optical port, an output optical port, a reference optical output port, a dispersion adjustment window, and a dispersion display window;

[0057] The dispersion adjustment is used to electrically or manually adjust the precision rotary stage 3 and the precision displacement stage 6. The angle of the first incident beam is adjusted by controlling the angle of the first plane mirror 2 through the precision rotary stage 3, so as to change the introduced negative second-order dispersion value. The distance between the corner mirror 5 and the first diffraction grating 4 is controlled by the precision displacement stage 6 to change the introduced negative second-order dispersion value.

[0058] like Figure 4 As shown, a crosshair is provided on the reference light output port, and a detection camera connected to an external computer is provided at the reference light output port. The incident light collimation is adjusted by observing the position of the 0th order light output in real time. When the 0th order light reflected by the second plane mirror 8 is located at the center of the crosshair, the incident light collimation is completed.

[0059] like Figure 5 As shown, when monochromatic light is incident on the surface of a diffraction grating at an incident angle γ, the light is diffracted and deflected. The diffraction angle γ-θ of the diffracted light changes with the wavelength.

[0060] sinγ+sin(γ-θ)=λ / d;

[0061] Where λ is the wavelength of the incident light, d is the spacing between the grating lines, and θ is the angle between the incident light and the diffracted light;

[0062] The relationship between the grating pair spacing G and the geometric path P of the beam between the grating pairs is as follows:

[0063]

[0064] The negative second-order dispersion φ introduced by the grating pair is:

[0065]

[0066] Where c is the speed of light;

[0067] The output pulse width after introducing the negative second-order dispersion φ” is:

[0068]

[0069] Where, τ in τ is the input pulse width. out The output pulse width;

[0070] According to the above formula, given the diffraction angle γ-θ of the diffracted light and the grating pair spacing G, the negative second-order dispersion φ” and the pulse width compression can be calculated and displayed in real time in the dispersion display window of the pulse compressor panel.

[0071] The collimated incident light is reflected by the first plane mirror 2 to the first diffraction grating 4. The light beam incident on the first diffraction grating 4 is the first incident beam. The first incident beam undergoes the first diffraction through the first diffraction grating 4 to form the first diffracted beam and the 0th order light is transmitted. The first diffracted beam is in a horizontal state at this time and illuminates the first reflecting surface of the corner mirror 5. The transmitted 0th order light is reflected by the second plane mirror 8 to the reference light output port. The 0th order light is in a horizontal state.

[0072] The first diffracted light is incident on the first reflecting surface of the corner mirror 5 and is reflected perpendicularly to the second reflecting surface. After being reflected by the second reflecting surface, it forms a second incident light beam, which is incident on the first diffraction grating 4 to form a second diffracted light beam. The second diffracted light beam is in a horizontal state at this time and diffracts to the high and low mirrors 7.

[0073] The high-low mirror 7 raises the second diffracted beam by a certain angle to form a third incident beam. The third incident beam is parallel to the second incident beam and has a height difference. Their projections on the horizontal plane coincide. The third incident beam passes through the first diffraction grating 4 to form the third diffracted beam.

[0074] The third diffracted beam is reflected a second time by the corner mirror 5 to form the fourth incident beam. The fourth incident beam undergoes a fourth diffraction by the first diffraction grating 4 to form the fourth diffracted beam. The fourth diffracted beam is incident on the first plane mirror 2. After being reflected by the first plane mirror 2, it forms a compressed beam output with pulse width compression. The output beam is parallel to the incident beam and has a height difference. The projections of the two on the horizontal plane coincide.

[0075] Based on the first pulse compressor structure disclosed above, this application provides a second pulse compressor structure. The difference from the first pulse compressor structure is that the corner mirror 5 is replaced with a second diffraction grating 11, and the first diffraction grating 4 and the second diffraction grating 11 can be a double-transmission grating, a double-reflection grating, or a single-transmission-single-reflection grating. A third plane mirror 10 is also added. Figure 2 As shown, the working process of the second type of pulse compressor is as follows:

[0076] The collimated incident light is reflected by the third plane mirror 10 and the first plane mirror 2 onto the second diffraction grating 11, forming a first diffracted beam and a 0th-order light reflection. The 0th-order light is reflected by the second plane mirror 8 to the reference light exit port, and the 0th-order light is in a horizontal state. The first diffracted beam is incident on the first diffraction grating 4 to form a second diffracted beam, and the elevation mirror 7 raises the second diffracted beam to a certain height.

[0077] The second diffracted beam, after being raised by the elevation mirror 7, is reflected to the first diffraction grating 4 to form the third diffracted beam. The third diffracted beam is incident on the second diffraction grating 11 to form the fourth diffracted beam. The fourth diffracted beam is incident on the first plane mirror 2 and reflected to the third plane mirror 10. After being reflected by the third plane mirror 10, it forms a compressed beam output with pulse width compression. The output beam is parallel to the incident beam and has a height difference. The projections of the two beams on the horizontal plane coincide.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An easily adjustable pulse compressor, characterized in that: It includes a collimating lens (1), a first plane mirror (2), a first diffraction grating (4), a corner mirror (5), an elevation mirror (7), and a second plane mirror (8). The collimating lens (1) and the input light port of the pulse compressor panel are both provided with pinhole apertures (9). The first plane mirror (2) is fixedly installed on a precision rotary stage (3), and the corner mirror (5) is fixedly installed on a precision displacement stage (6). Collimating lens (1), incident light enters pinhole aperture (9) through collimating lens (1); A small aperture (9) is used to collimate the incident light to the first plane mirror (2). The first plane mirror (2) receives the collimated incident light and reflects it to form a first incident beam that is incident on the first diffraction grating (4); it receives the fourth diffraction beam generated by the first diffraction grating (4) and reflects it to form a compressed beam after pulse width compression that is incident on the output light port of the pulse compressor panel. The first diffraction grating (4) receives the first incident beam generated by the first plane mirror (2) and undergoes the first diffraction to form the first diffracted beam and the 0th order light; it receives the second incident beam generated by the corner mirror (5) and undergoes the second diffraction to form the second diffracted beam; it receives the third incident beam generated by the high-low mirror (7) and undergoes the third diffraction to form the third diffracted beam; it then receives the fourth incident beam generated by the corner mirror (5) and undergoes the fourth diffraction to form the fourth diffracted beam. The corner mirror (5) receives the first diffracted beam generated by the first diffraction grating (4) and reflects it to form a second incident beam that is incident on the first diffraction grating (4); it also receives the third diffracted beam generated by the first diffraction grating (4) and reflects it to form a fourth incident beam that is incident on the first diffraction grating (4). The high-low mirror (7) receives the first diffraction beam generated by the first diffraction grating (4) and raises the light to a certain height to form a third incident beam that is incident on the first diffraction grating (4). The second plane mirror (8) receives the 0th order light generated by the first diffraction grating (4) and reflects the 0th order light to the reference light output port of the pulse compressor panel; The pulse compressor panel includes an input optical port, an output optical port, a reference optical output port, a dispersion adjustment and dispersion display window; The dispersion adjustment is used to electrically or manually adjust the precision rotary stage (3) and the precision displacement stage (6). The angle of the first plane mirror (2) is controlled by the precision rotary stage (3) to adjust the incident angle of the first incident beam, thereby changing the introduced negative second-order dispersion value. The distance between the corner mirror (5) and the first diffraction grating (4) is controlled by the precision displacement stage (6) to change the introduced negative second-order dispersion value. When monochromatic light is at an angle of incidence When light is incident on the surface of a diffraction grating, it is diffracted and deflected. The diffraction angle of the diffracted light is... Changes with wavelength: ； in, λ is the wavelength of the incident light, and d is the spacing between the grating lines. The angle between the incident light and the diffracted light; The relationship between the grating pair spacing G and the geometric path P of the beam between the grating pairs is as follows: ； Negative second-order dispersion introduced by the grating pair for: ； Where c is the speed of light; Introducing negative second-order dispersion The output pulse width after that is: ； in, The input pulse width, The output pulse width; According to the above formula, given the diffraction angle of the diffracted light... Given the grating pair spacing G, the negative second-order dispersion can be calculated. The pulse width compression is displayed in real time in the dispersion display window on the pulse compressor panel.

2. The easily adjustable pulse compressor according to claim 1, characterized in that: The first diffraction grating (4) is a transmission grating or a reflection grating, and the grating lines of the first diffraction grating (4) are in the vertical direction.

3. The easily adjustable pulse compressor according to claim 1, characterized in that: The corner mirror (5) consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the vertical direction.

4. The easily adjustable pulse compressor according to claim 1, characterized in that: The high-low mirror (7) consists of two mirrors with a right angle between them, and the intersection line of the two mirrors is in the horizontal direction.

5. The easily adjustable pulse compressor according to claim 1, characterized in that: The reference light output port is provided with a crosshair, and a detection camera connected to an external computer is provided at the reference light output port. The incident light collimation is adjusted by observing the position of the 0th order light output in real time. When the 0th order light reflected by the second plane mirror (8) is located at the center of the crosshair, the incident light collimation is completed.

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