Pulse compressor convenient to adjust

Abstract

The invention relates to a pulse compressor, in particular to a pulse compressor convenient to adjust, which comprises a collimating lens, a first plane reflecting mirror, a first diffraction grating, an angle reflecting mirror, a high-low mirror and a second plane reflecting mirror, the first plane mirror is fixedly installed on the precision rotating table, and the angle mirror is fixedly installed on the precision displacement table. According to the technical scheme provided by the invention, the defects in the prior art that different pulse width compression amounts are inconvenient to obtain by changing the relative interval of the grating and adjusting the introduced negative dispersion value through the diffraction angle of the grating, and collimation adjustment of the incident light is inconvenient can be effectively overcome.

Description

Technical Field

[0001] The invention relates to a pulse compressor, in particular to a pulse compressor which is easy to adjust. Background Art

[0002] Femtosecond lasers are widely used in the fields of fine micro-machining of materials, semiconductors, solar photovoltaics, etc. due to their extremely high peak power and extremely narrow pulse width. When used for material processing, femtosecond lasers use extremely short-duration light pulses to interact with matter, and can inject all of their energy into a very small action area at an extremely fast speed, and the thermal effect of the material is well controlled. Compared with nanosecond and picosecond lasers, the use of femtosecond lasers to process materials has the advantages of high precision, small heat-affected area, and no burrs on the processed edges.

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

[0004] Laser pulse compression is generally achieved using a grating pair compressor. The working principle of the grating pair compressor is that when a positively chirped pulse passes through a parallel grating, different spectral components experience different optical path lengths, with the optical path experienced by a long wavelength being greater than that experienced by a short wavelength. Pulse compression is achieved by introducing a negative dispersion-compensating positive chirp that is conjugated with a stretcher.

[0005] At present, the pulse width compression of the pulse compressor is achieved by adjusting the negative dispersion value introduced by changing the relative spacing of the gratings and the diffraction angle of the gratings. In order to obtain different pulse width compression amounts, the relative distance of the gratings and the diffraction angle of the gratings in the pulse compressor need to be adjustable, and the grating pairs need to be placed strictly in parallel, so the angle adjustment has very high requirements on the rotation accuracy of the rotating stage; at the same time, as an independent and integrable module, the pulse compressor needs to collimate the angle and height of the incident light. Summary of the invention

[0006] 1. Technical issues to be resolved

[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 that it is not convenient to adjust 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 it is not convenient to collimate the incident light.

[0008] (II) Technical solution

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] A pulse compressor that is easy to adjust, comprising a collimating lens, a first plane reflector, a first diffraction grating, an angle reflector, a high-low mirror and a second plane reflector, wherein a small aperture diaphragm is provided on the surface of the collimating lens and at the input light port of the pulse compressor panel, the first plane reflector is fixedly mounted on a precision rotating stage, and the angle reflector is fixedly mounted on a precision displacement stage;

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

[0012] A pinhole aperture allows the collimated incident light to be incident on the first plane reflector;

[0013] The first plane reflector receives the collimated incident light and reflects it to form a first incident light beam which is incident on the first diffraction grating; receives the fourth diffraction light beam generated by the first diffraction grating and reflects it to form a compressed light beam after pulse width compression which is incident on the output light port of the pulse compressor panel;

[0014] The first diffraction grating receives the first incident light beam generated by the first plane reflector, and performs a first diffraction to form a first diffracted light beam and a 0th order light; receives the second incident light beam generated by the angle reflector, and performs a second diffraction to form a second diffracted light beam; receives the third incident light beam generated by the height reflector, and performs a third diffraction to form a third diffracted light beam; receives the fourth incident light beam generated by the angle reflector again, and performs a fourth diffraction to form a fourth diffracted light beam;

[0015] A corner mirror receives a first diffraction light beam generated by the first diffraction grating, reflects the first diffraction light beam to form a second incident light beam, and then enters the first diffraction grating; receives a third diffraction light beam generated by the first diffraction grating, reflects the first diffraction light beam to form a fourth incident light beam, and then enters the first diffraction grating;

[0016] The elevation mirror receives the first diffraction light beam generated by the first diffraction grating, and raises the light to a certain height to form a third incident light beam incident on the first diffraction grating;

[0017] The second plane reflecting mirror receives the 0th order light generated by the first diffraction grating, and reflects the 0th order light to the reference light outlet of the pulse compressor panel.

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

[0019] Preferably, the corner reflector is composed of two reflectors with a right angle, and the intersection line of the two reflectors is in the vertical direction.

[0020] Preferably, the high and low mirrors are composed of two reflectors with a right angle, and the intersection line of the two reflectors is in the horizontal direction.

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

[0022] Among them, the dispersion adjustment is used for electrically or manually adjusting the precision rotating stage and the precision translation stage. The incident angle of the first incident light beam is adjusted by controlling the angle of the first plane reflector through the precision rotating stage to change the introduced negative second-order dispersion value; the distance between the angle reflector and the first diffraction grating is controlled by the precision translation stage to change the introduced negative second-order dispersion value.

[0023] Preferably, a cross mark is provided on the reference light outlet, and a detection camera connected to an external computer is provided at the reference light outlet. The incident light collimation adjustment is performed by observing the 0th order light exit position in real time. When the 0th order light reflected by the second plane reflector is located at the center of the cross mark, the incident light collimation adjustment 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 light beam between the grating pairs is:

[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 negative second-order dispersion φ" is:

[0033]

[0034] Among them, τ in is the input pulse width, τ out is the output pulse width;

[0035] According to the above formula, when the diffraction angle γ-θ of the diffracted light and the grating pair spacing G are known, the negative second-order dispersion φ" and the pulse width compression amount 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 present invention provides an easily adjustable pulse compressor, which adjusts the incident angle of the first incident light beam by controlling the angle of the first plane reflector through a precision rotating table, and controls the distance between the angle reflector and the first diffraction grating through a precision displacement table to change the introduced negative second-order dispersion value, thereby being able to very conveniently obtain different pulse width compression amounts; a cross mark is provided on the reference light outlet, and when the 0th order light reflected by the second plane reflector is located at the center of the cross mark, the incident light collimation adjustment is completed, making the incident light collimation adjustment convenient and quick. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] Figure 1 It is a first structural schematic diagram of the present invention;

[0040] Figure 2 It is a second structural schematic diagram of the present invention;

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

[0042] Figure 4 For the present invention Figure 3 A schematic diagram of the enlarged structure of the reference light outlet;

[0043] Figure 5 Schematic diagram of grating pair dispersion. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] A pulse compressor that is easily adjustable, such as Figure 1 As shown, it includes a collimating lens 1, a first plane reflector 2, a first diffraction grating 4, a corner reflector 5, a high-low mirror 7 and a second plane reflector 8. A pinhole diaphragm 9 is provided at the surface of the collimating lens 1 and the input light port of the pulse compressor panel. The first plane reflector 2 is fixedly mounted on a precision rotating stage 3, and the corner reflector 5 is fixedly mounted on a precision translation stage 6.

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

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

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

[0049] The first diffraction grating 4 receives the first incident light beam generated by the first plane reflector 2, and performs the first diffraction to form the first diffracted light beam and the 0th order light; receives the second incident light beam generated by the corner reflector 5, and performs the second diffraction to form the second diffracted light beam; receives the third incident light beam generated by the high-low mirror 7, and performs the third diffraction to form the third diffracted light beam; receives the fourth incident light beam generated by the corner reflector 5 again, and performs the fourth diffraction to form the fourth diffracted light beam;

[0050] The corner reflector 5 receives the first diffraction light beam generated by the first diffraction grating 4, and reflects it to form a second incident light beam incident to the first diffraction grating 4; receives the third diffraction light beam generated by the first diffraction grating 4, and reflects it to form a fourth incident light beam incident to the first diffraction grating 4;

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

[0052] The second plane reflector 8 receives the 0th order light generated by the first diffraction grating 4, and reflects the 0th order light to the reference light outlet of the pulse compressor panel.

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

[0054] The corner reflector 5 is composed of two reflectors with a right angle, and the intersection line of the two reflectors is in the vertical direction.

[0055] The high-low mirror 7 is composed of two reflectors with a right angle, and the intersection line of the two reflectors is in the horizontal direction.

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

[0057] Among them, the dispersion adjustment is used to electrically or manually adjust the precision rotating stage 3 and the precision translation stage 6. The angle of the first plane reflector 2 is controlled by the precision rotating stage 3 to adjust the incident angle of the first incident light beam to change the introduced negative second-order dispersion value; the distance between the corner reflector 5 and the first diffraction grating 4 is controlled by the precision translation stage 6 to change the introduced negative second-order dispersion value.

[0058] like Figure 4 As shown, a cross mark is provided on the reference light outlet, and a detection camera connected to an external computer is provided at the reference light outlet. The incident light collimation is adjusted by observing the 0-level light exit position in real time. When the 0-level light reflected by the second plane reflector 8 is located at the center of the cross mark, the incident light collimation adjustment is completed.

[0059] like Figure 5 As shown in Figure 1, 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:

[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 light beam between the grating pairs is:

[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 negative second-order dispersion φ" is:

[0068]

[0069] Among them, τ in is the input pulse width, τ out is the output pulse width;

[0070] According to the above formula, when the diffraction angle γ-θ of the diffracted light and the grating pair spacing G are known, the negative second-order dispersion φ" and the pulse width compression amount 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 reflector 2 to the first diffraction grating 4. The light beam incident on the first diffraction grating 4 is the first incident light beam. The first incident light beam undergoes a first diffraction by the first diffraction grating 4 to form a first diffraction light beam and 0-order light transmission. The first diffraction light beam is in a horizontal state at this time and irradiates the first reflecting surface of the corner mirror 5, and the transmitted 0-order light is reflected by the second plane reflector 8 to the reference light outlet, and the 0-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 vertically reflected to the second reflecting surface. After being reflected by the second reflecting surface, a second incident light beam is formed and 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 is diffracted to the high-low mirror 7.

[0073] The elevation 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. The projections on the horizontal plane overlap. The third incident beam passes through the first diffraction grating 4 to form a third diffracted beam.

[0074] The third diffracted light beam is reflected for the second time by the corner mirror 5 to form a fourth incident light beam. The fourth incident light beam is diffracted for the fourth time by the first diffraction grating 4 to form a fourth diffracted light beam. The fourth diffracted light beam is incident on the first plane reflector 2, and is reflected by the first plane reflector 2 to form a compressed light beam output after pulse width compression. The output light is parallel to the incident light and there is a height difference between them, and the projections of the two on the horizontal plane coincide.

[0075] Based on the first pulse compressor structure disclosed above, the technical solution of the present application provides a second pulse compressor structure, which is different from the first pulse compressor structure in that the corner reflector 5 is replaced by the second diffraction grating 11, and the first diffraction grating 4 and the second diffraction grating 11 can be double transmission gratings, double reflection gratings or one transmission and one reflection grating, and a third plane reflector 10 is added. Figure 2 As shown, the working process of the second pulse compressor is as follows:

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

[0077] The second diffraction beam raised by the height mirror 7 is reflected to the first diffraction grating 4 to form a third diffraction beam. The third diffraction beam is incident on the second diffraction grating 11 to form a fourth diffraction beam. The fourth diffraction beam is incident on the first plane reflector 2 and reflected to the third plane reflector 10. After being reflected by the third plane reflector 10, a compressed beam output after pulse width compression is formed. The output light is parallel to the incident light and there is a height difference between them. The projections of the two on the horizontal plane coincide.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements 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. A pulse compressor that is easy to adjust, characterized in that: The invention comprises a collimating lens (1), a first plane reflecting mirror (2), a first diffraction grating (4), an angle reflecting mirror (5), a high-low mirror (7) and a second plane reflecting mirror (8); a small aperture diaphragm (9) is provided at the surface of the collimating lens (1) and the input light port of the pulse compressor panel; the first plane reflecting mirror (2) is fixedly mounted on a precision rotating platform (3); and the angle reflecting mirror (5) is fixedly mounted on a precision displacement platform (6); A collimating lens (1), through which incident light enters a pinhole aperture (9); A pinhole diaphragm (9) allows the collimated incident light to be incident on the first plane reflector (2); The first plane reflector (2) receives the collimated incident light and reflects it to form a first incident light beam which is incident on the first diffraction grating (4); receives the fourth diffraction light beam generated by the first diffraction grating (4), and reflects it to form a compressed light beam after pulse width compression which is incident on the output light port of the pulse compressor panel; The first diffraction grating (4) receives the first incident light beam generated by the first plane reflector (2), and performs a first diffraction to form a first diffracted light beam and a zero-order light beam; receives the second incident light beam generated by the angle reflector (5), and performs a second diffraction to form a second diffracted light beam; receives the third incident light beam generated by the height reflector (7), and performs a third diffraction to form a third diffracted light beam; and receives the fourth incident light beam generated by the angle reflector (5) again, and performs a fourth diffraction to form a fourth diffracted light beam; A corner reflector (5) receives a first diffraction light beam generated by the first diffraction grating (4), reflects the light to form a second incident light beam, and then enters the first diffraction grating (4); receives a third diffraction light beam generated by the first diffraction grating (4), reflects the light to form a fourth incident light beam, and then enters the first diffraction grating (4); A high-low mirror (7) receives a first diffraction light beam generated by the first diffraction grating (4), and raises the light to a certain height to form a third incident light beam that is incident on the first diffraction grating (4); The second plane reflector (8) receives the 0th order light generated by the first diffraction grating (4), and reflects the 0th order light to the reference light outlet of 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 engraved lines of the first diffraction grating (4) are in a vertical direction.

3. The easily adjustable pulse compressor according to claim 1, characterized in that: The corner reflector (5) is composed of two reflectors whose included angle is a right angle, and the intersection line of the two reflectors is in the vertical direction.

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

5. The easily adjustable pulse compressor according to claim 1, characterized in that: The panel of the pulse compressor includes an input light port, an output light port, a reference light output port, and a dispersion adjustment and dispersion display window; The dispersion adjustment is used to electrically or manually adjust the precision rotating stage (3) and the precision displacement stage (6); the angle of the first plane reflector (2) is controlled by the precision rotating stage (3) to adjust the incident angle of the first incident light beam so as to change the introduced negative second-order dispersion value; and the distance between the angle reflector (5) and the first diffraction grating (4) is controlled by the precision displacement stage (6) to change the introduced negative second-order dispersion value.

6. The easily adjustable pulse compressor according to claim 5, characterized in that: A cross mark is arranged on the reference light outlet, and a detection camera connected to an external computer is arranged at the reference light outlet. The collimation adjustment of the incident light is performed by observing the 0-order light outlet position in real time. When the 0-order light reflected by the second plane reflector (8) is located at the center of the cross mark, the collimation adjustment of the incident light is completed.

7. The easily adjustable pulse compressor according to claim 5, characterized in that: 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: sinγ+sin(γ-θ)=λ / d; 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; The relationship between the grating pair spacing G and the geometric path P of the light beam between the grating pairs is: The negative second-order dispersion φ” introduced by the grating pair is: Where c is the speed of light; The output pulse width after introducing negative second-order dispersion φ" is: Among them, τ in is the input pulse width, τ out is the output pulse width; According to the above formula, when the diffraction angle γ-θ of the diffracted light and the grating pair spacing G are known, the negative second-order dispersion φ" and the pulse width compression amount can be calculated and displayed in real time in the dispersion display window of the pulse compressor panel.

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