A 248.3nm single-frequency all-solid-state deep ultraviolet laser system and method

Abstract

The present invention belongs to the field of laser technology. In order to solve the complex problems of the existing deep ultraviolet laser system, a 248.3nm single-frequency all-solid-state deep ultraviolet laser system and method are provided. Among them, the 248.3nm single-frequency all-solid-state deep ultraviolet laser system includes a seed laser source optical path, a triple frequency optical path, an optical parametric oscillator optical path and a sum frequency optical path; the seed laser source optical path sequentially modulates and amplifies the set wavelength single-frequency seed laser, and then performs light splitting processing, and then transmits it to the triple frequency optical path and the optical parametric oscillator optical path respectively; the triple frequency optical path generates 1 / 3 times the set laser and outputs it to the sum frequency optical path; the optical parametric oscillator optical path generates a laser with a matching wavelength through optical parametric oscillation and outputs it to the sum frequency optical path; the sum frequency optical path performs sum frequency to generate a 248.3nm deep ultraviolet laser. It does not require a complex external timing control circuit, can greatly reduce the system complexity and cost, and improve the system stability and reliability.

Description

Technical Field

[0001] The invention belongs to the technical field of lasers, and in particular relates to a 248.3nm single-frequency all-solid-state deep ultraviolet laser system and method. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Since the materials commonly used in fiber Bragg gratings are sensitive to 248.3nm light sources and have good etching characteristics, 248.3nm light sources are widely used in fiber Bragg grating etching. At the same time, 248.3nm light sources are the third generation of lithography light sources after G-line and I-line, and can be used in integrated circuit lithography to achieve 130nm nodes.

[0004] At present, the main solutions for obtaining 248.3nm deep ultraviolet laser output include the following:

[0005] (1) Using a KrF excimer laser as a seed source to obtain a 248.3nm excimer laser output, which is then amplified by a multi-stage excimer amplifier to obtain a 248.3nm laser output. Although this method can achieve an output power of more than 400 watts, it is relatively complicated to develop and use, and consumables need to be replaced regularly.

[0006] (2) Using a 745nm laser with titanium sapphire or alexandrite as a gain crystal, the 248.3nm laser output is obtained as a seed source through nonlinear frequency conversion, and then amplified by a multi-stage KrF excimer amplifier. This method uses an all-solid-state 248.3nm laser to replace the KrF excimer laser as a seed source, which makes up for the problem of poor beam quality of the traditional seed source and can obtain a high-quality 248.3nm laser output. However, the current method of obtaining an all-solid-state 248.3nm deep ultraviolet laser is limited by the thermal effect of the gain crystal and the immature pump source, making it difficult to obtain an efficient, miniaturized and low-cost 248.3nm laser.

[0007] (3) Using 1064nm Nd:YAG and 1645nm Er:YAG lasers as fundamental frequency light, all-solid-state 248.3nm deep ultraviolet laser output is obtained through nonlinear frequency conversion. However, this method requires two fundamental frequency lights and requires complex external timing synchronization circuits for control, which increases the complexity of the system, making the entire system complicated and the device bulky. Summary of the invention

[0008] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a 248.3nm single-frequency all-solid-state deep ultraviolet laser system and method, which does not require a complex external timing control circuit, can greatly reduce the system complexity and cost, improve the system stability and reliability, and simplify daily maintenance, which is conducive to the integration and miniaturization of 248.3nm light sources.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] A first aspect of the present invention provides a 248.3 nm single-frequency all-solid-state deep ultraviolet laser system.

[0011] A 248.3nm single-frequency all-solid-state deep ultraviolet laser system, comprising: a seed laser source optical path, a triple frequency optical path, an optical parametric oscillator optical path and a sum frequency optical path;

[0012] The seed laser source optical path is used to: The single-frequency seed laser is modulated and amplified in sequence, and then subjected to light splitting processing, and then transmitted to the triple frequency optical path and the optical parametric oscillator optical path respectively; the wavelength of the single-frequency seed laser is The range is 1000nm-1100nm;

[0013] The triple frequency optical path is used to generate a wavelength of The laser is output to the sum frequency optical path;

[0014] The optical parametric oscillator optical path is used to generate a wavelength of The laser is output to the sum frequency optical path;

[0015] The sum frequency optical path is used to: The laser and wavelength are The laser is combined with the frequency to generate 248.3nm deep ultraviolet laser.

[0016] As an implementation method, the triple frequency optical path is used to: convert the received laser into a wavelength of Laser, output wavelength is The laser and wavelength are The laser with wavelength The laser and wavelength are After the laser is processed by frequency summation, the wavelength is of laser.

[0017] As an embodiment, the optical parametric oscillator optical path is used to: convert the received laser into a wavelength of Laser, then the wavelength is The laser is converted into a wavelength of of laser.

[0018] As an embodiment, the seed laser source optical path includes wavelengths arranged in sequence along the optical path. Single-frequency seed laser, acousto-optic modulator, fiber amplifier, solid-state amplifier, first reflector and spectroscope.

[0019] As an implementation manner, the triple frequency optical path includes a first frequency doubling nonlinear optical crystal, a first sum frequency nonlinear optical crystal and a first dichroic mirror which are sequentially arranged along the optical path.

[0020] As an embodiment, the optical parametric oscillator optical path includes a second reflector, a second frequency doubling nonlinear optical crystal, a second dichroic mirror, a third dichroic mirror, a reflective volume Bragg grating, an optical parametric oscillator nonlinear optical crystal, an optical parametric oscillator output mirror and a fourth dichroic mirror arranged in sequence along the optical path.

[0021] As an implementation mode, a second sum frequency nonlinear optical crystal is provided on the sum frequency optical path; the second sum frequency nonlinear optical crystal is used to receive a wavelength of The laser and wavelength are The laser is frequency combined to obtain 248.3nm deep ultraviolet laser.

[0022] As an implementation manner, a fifth dichroic mirror and a sixth dichroic mirror are sequentially arranged on the sum frequency optical path; the 248.3 nm deep ultraviolet laser is then output through the fifth dichroic mirror and the sixth dichroic mirror in sequence.

[0023] As an embodiment, the fifth dichroic mirror and the sixth dichroic mirror are both coated with a dielectric film, and the dielectric film reflects the laser with a wavelength of 248.3 nm and transmits Wavelength and wavelength of laser light.

[0024] The second aspect of the present invention provides a 248.3nm single-frequency all-solid-state deep ultraviolet laser output method.

[0025] A 248.3nm single-frequency all-solid-state deep ultraviolet laser output method, comprising:

[0026] For wavelength The single-frequency seed laser is modulated and amplified in turn, and the amplified wavelength is The laser is split and processed into two paths;

[0027] After frequency doubling and sum frequency processing, one of the channels generates a wavelength of Laser

[0028] The other path is processed by frequency doubling and optical parametric oscillation to produce a wavelength of Laser

[0029] Finally, the wavelength is The laser and wavelength are The laser is combined with the frequency to generate 248.3nm deep ultraviolet laser.

[0030] The beneficial effects of the present invention are:

[0031] (1) The present invention only uses a single-frequency laser with a preset wavelength as the fundamental frequency light, and realizes a 248.3nm single-frequency all-solid-state deep ultraviolet laser output with high beam quality through nonlinear frequency conversion technology; the single-frequency fundamental frequency light is easy to obtain, and due to the extremely narrow line width, it has a high conversion efficiency in nonlinear frequency conversion.

[0032] (2) The present invention only uses the wavelength of a single-frequency seed laser A light source with a wavelength range of 1000nm-1100nm is used as the fundamental frequency light, and combined with the triple frequency optical path, the optical parametric oscillator optical path and the sum frequency optical path. Compared with other solutions using multiple fundamental frequency lights, there is no need for complex external timing control circuits, which can greatly reduce system complexity and cost, improve system stability and reliability, simplify daily maintenance, and is conducive to the integration and miniaturization of 248.3nm light sources.

[0033] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0035] Figure 1 It is a schematic diagram of the structure of a 248.3nm single-frequency all-solid-state deep ultraviolet laser system according to an embodiment of the present invention.

[0036] Among them, 1. single-frequency 1064nm seed laser; 2. acousto-optic modulator; 3. optical fiber amplifier; 4. solid-state amplifier; 5. first reflector; 6. spectrometer; 7. first frequency-doubling nonlinear optical crystal; 8. first sum frequency nonlinear optical crystal; 9. second reflector; 10. second frequency-doubling nonlinear optical crystal; 11. second dichroic mirror; 12. third dichroic mirror; 13. reflective volume Bragg grating; 14. optical parametric oscillator nonlinear optical crystal; 15. optical parametric oscillator output mirror; 16. fourth dichroic mirror; 17. first dichroic mirror; 18. second sum frequency nonlinear optical crystal; 19. fifth dichroic mirror; 20. sixth dichroic mirror. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0038] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0039] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0040] The embodiment of the present invention provides a 248.3nm single-frequency all-solid-state deep ultraviolet laser system, which includes: a seed laser source optical path, a triple frequency optical path, an optical parametric oscillator optical path and a sum frequency optical path;

[0041] The seed laser source optical path is used to: The single-frequency seed laser is modulated and amplified in sequence, and then subjected to light splitting processing, and then transmitted to the triple frequency optical path and the optical parametric oscillator optical path respectively; the wavelength of the single-frequency seed laser is The range is 1000nm-1100nm;

[0042] The triple frequency optical path is used to generate a wavelength of The laser is output to the sum frequency optical path;

[0043] The optical parametric oscillator optical path is used to generate a wavelength of The laser is output to the sum frequency optical path;

[0044] The sum frequency optical path is used to: The laser and wavelength are The laser is combined with the frequency to generate 248.3nm deep ultraviolet laser.

[0045] This embodiment only uses the wavelength of a single-frequency seed laser A light source with a wavelength range of 1000nm-1100nm is used as the fundamental frequency light, and combined with the triple frequency optical path, the optical parametric oscillator optical path and the sum frequency optical path. Compared with other solutions using multiple fundamental frequency lights, there is no need for complex external timing control circuits, which can greatly reduce system complexity and cost, improve system stability and reliability, simplify daily maintenance, and is conducive to the integration and miniaturization of 248.3nm light sources.

[0046] The wavelength of the single-frequency seed laser is Take 1064nm as an example to combine the attached Figure 1 The specific implementation process of the embodiment of the present invention is described in detail.

[0047] like Figure 1 As shown, the seed laser source optical path includes a single-frequency 1064nm seed laser 1, an acousto-optic modulator 2, a fiber amplifier 3, a solid amplifier 4, a first reflector 5 and a beam splitter 6 which are sequentially arranged along the optical path.

[0048] Specifically, the single-frequency 1064nm seed laser 1 adopts a fiber DFB (Distributed Feedback Laser) structure and is pumped by a 976nm LD (Laser Diode) to obtain a single-frequency, narrow-linewidth, and mode-hopping-free 1064nm seed laser.

[0049] The acousto-optic modulator 2 adopts a fiber-coupled acousto-optic modulator, which is used to modulate the continuous 1064 nm laser into a pulsed laser.

[0050] The optical fiber amplifier 3 adopts 976nm diode pumping and uses ytterbium-doped optical fiber as gain optical fiber to realize pre-amplification of modulated 1064nm pulse laser.

[0051] The solid-state amplifier 4 is an end-pumped Nd:YVO4 amplifier, which amplifies the pre-amplified 1064nm fundamental frequency light to a higher power and maintains a beam quality close to the diffraction limit.

[0052] The first reflector 5 is coated with a 1064nm high-reflection dielectric film, and the incident angle is 45°.

[0053] Beam splitter 6, with a design wavelength of 1064 nm and a transmission-reflection ratio of 37:63.

[0054] In this embodiment, the triple frequency optical path is used to: convert the received amplified 1064nm laser into 532nm laser through frequency doubling, output 1064nm laser and 532nm laser; and then generate 354.7nm laser after frequency sum processing of the 1064nm laser and the 532nm laser.

[0055] like Figure 1As shown, the triple frequency optical path includes a first frequency doubling nonlinear optical crystal 7, a first sum frequency nonlinear optical crystal 8 and a first dichroic mirror 17 which are sequentially arranged along the optical path.

[0056] The first frequency doubling nonlinear optical crystal 7 is a temperature phase matched or angle phase matched LBO (LiB 3 O 5 , lithium triborate) nonlinear optical crystal, and both ends of the LBO nonlinear optical crystal are coated with 1064nm and 532nm high-transmittance dielectric films. The advantage of this design is that the 1064nm laser can be converted into 532nm laser through nonlinear frequency conversion technology using this frequency-doubling nonlinear optical crystal.

[0057] The first sum frequency nonlinear optical crystal 8 is a temperature phase matched or angle phase matched LBO nonlinear optical crystal, and both end faces of the LBO nonlinear optical crystal are coated with 1064nm, 532nm and 354.7nm high-transmittance dielectric films. The advantage of this design is that the sum frequency nonlinear optical crystal can generate a 354.7nm laser output by sum frequency technology by sum frequency combining 1064nm laser and 532nm laser.

[0058] The first dichroic mirror 17 is coated with a dielectric film that is highly reflective to 1064nm and 532nm and highly transparent to 354.7nm, and the incident angle is 45°.

[0059] In this embodiment, the optical parametric oscillator optical path is used to: convert the received amplified 1064nm laser into 532nm laser through frequency doubling, and then convert the 532nm laser into 827.7nm laser through optical parametric oscillation.

[0060] like Figure 1 As shown, the optical parametric oscillator optical path includes a second reflector 9, a second frequency doubling nonlinear optical crystal 10, a second dichroic mirror 11, a third dichroic mirror 12, a reflective volume Bragg grating 13, an optical parametric oscillator nonlinear optical crystal 14, an optical parametric oscillator output mirror 15 and a fourth dichroic mirror 16 which are arranged in sequence along the optical path.

[0061] Specifically, the second reflector 9 is coated with a 1064nm high-reflection dielectric film, and the incident angle is 45°.

[0062] The second frequency doubling nonlinear optical crystal 10 is a temperature phase-matched LBO nonlinear optical crystal, and both end faces are coated with dielectric films with high transmittance to 1064 nm and 532 nm.

[0063] The second dichroic mirror 11 and the third dichroic mirror 12 are coated with a dielectric film with high transmittance at 1064 nm and high reflectivity at 532 nm, and the incident angle is 45°.

[0064] The reflective volume Bragg grating 13 has a central wavelength of 827.7 nm, a diffraction efficiency greater than 99%, a line width of only 30 pm, and an end face coated with an 827.7 nm anti-reflection dielectric film.

[0065] The optical parametric oscillator nonlinear optical crystal 14 is a temperature phase-matched LBO nonlinear optical crystal, and both end faces of the LBO nonlinear optical crystal are coated with 532nm, 827.7nm and 1491nm high-transmittance dielectric films. The advantage of this design is that the 532nm laser is converted into 827.7nm laser output by using the nonlinear optical crystal through the optical parametric oscillation technology.

[0066] The optical parametric oscillator output mirror 15 is coated with a dielectric film with high reflection at 532nm, high transmission at 1491nm and a transmittance of 30% at 827.7nm, and the incident angle is 0°.

[0067] The fourth dichroic mirror 16 is coated with a dielectric film with high transmittance at 532nm and 1491nm and high reflectivity at 827.7nm, and the incident angle is 45°.

[0068] like Figure 1 As shown, a second sum frequency nonlinear optical crystal 18 is provided on the sum frequency optical path; the second sum frequency nonlinear optical crystal 18 is used to sum frequency the received 827.7nm and 354.7nm lasers to obtain 248.3nm deep ultraviolet lasers.

[0069] The second frequency-sum nonlinear optical crystal 18 is an angle-phase-matched BBO (barium borate) or CLBO (CsLiB 6 O 10 , cesium lithium hexaborate) nonlinear optical crystal, both ends of the BBO nonlinear optical crystal are coated with anti-reflection films for 827.7nm, 354.7nm and 248.3nm, and the cutting angle is 47.4° or 57.9°; the CLBO nonlinear optical crystal is uncoated, and the cutting angle is 61.7°. The advantage of this design is that the coating on the surface of CLBO is easy to cause damage, and the CLBO crystal has a high transmittance for 827.7nm, 354.7nm and 248.3nm, so no coating can reduce the risk of damage. At the same time, the CLBO nonlinear optical crystal has a small walk-off angle, so better beam quality can be obtained. Using BBO or CLBO nonlinear optical crystals, 827.7nm and 354.7nm lasers can be converted into 248.3nm deep ultraviolet lasers through nonlinear frequency conversion technology.

[0070] A fifth dichroic mirror 19 and a sixth dichroic mirror 20 are sequentially arranged on the sum frequency optical path; the 248.3 nm deep ultraviolet laser is then outputted through the fifth dichroic mirror 19 and the sixth dichroic mirror 20 in sequence.

[0071] Specifically, the fifth dichroic mirror 19 and the sixth dichroic mirror 20 are both coated with a dielectric film with high reflection at 248.3 nm and high transmittance at 354.7 nm and 827.7 nm, and the incident angle is 45°.

[0072] In one or more embodiments, a 248.3 nm single-frequency all-solid-state deep ultraviolet laser output method is also provided, comprising:

[0073] The single-frequency 1064nm seed laser is modulated and amplified in sequence to obtain an amplified 1064nm laser and then split into two paths;

[0074] One of them is processed by frequency doubling and sum frequency in turn to generate 354.7nm laser;

[0075] The other one generates 827.7nm laser after frequency doubling and optical parametric oscillation processing;

[0076] Finally, the 827.7nm and 354.7nm lasers are frequency-added to generate 248.3nm deep ultraviolet lasers.

[0077] It should be noted here that the wavelength of the single-frequency seed laser You can also choose any value between 1000nm and 1100nm. For example, when the wavelength of the single-frequency seed laser is When the wavelength is 1030nm, the wavelength of the corresponding doubled frequency light is 515nm, and the wavelength of the tripled frequency light is 343nm; in order to obtain 248nm, the wavelength of the light output by the optical parametric oscillator optical path is 882nm. The phase matching angle or temperature of the nonlinear crystal in each link is set accordingly.

[0078] In some optional embodiments, gain crystals (Nd:YVO4, Nd:YAG, Nd:YLF, Nd:YAP, Yb:YAG, etc.) with wavelengths of A solid laser in the range of 1000nm-1100nm is used as the fundamental frequency light, the optical parametric oscillator nonlinear optical crystal can be specifically selected according to the actual situation, and the splitting ratio of the beam splitter can also be specifically set according to the actual situation.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A 248.3nm single-frequency all-solid-state deep ultraviolet laser system, characterized in that: include: Seed laser source optical path, frequency tripling optical path, optical parametric oscillator optical path and sum frequency optical path; The seed laser source optical path is used to: The single-frequency seed laser is modulated and amplified in sequence, and then subjected to light splitting processing, and then transmitted to the triple frequency optical path and the optical parametric oscillator optical path respectively; the wavelength of the single-frequency seed laser is The range is 1000nm-1100nm; The seed laser source optical path includes wavelengths arranged in sequence along the optical path: Single frequency seed laser, acousto-optic modulator, fiber amplifier, solid amplifier, first reflector and beam splitter; The triple frequency optical path is used to generate a wavelength of The laser is output to the sum frequency optical path; The optical parametric oscillator optical path is used to generate a wavelength of The laser is output to the sum frequency optical path; The optical parametric oscillator optical path includes a second reflector, a second frequency doubling nonlinear optical crystal, a second dichroic mirror, a third dichroic mirror, a reflective volume Bragg grating, an optical parametric oscillator nonlinear optical crystal, an optical parametric oscillator output mirror and a fourth dichroic mirror which are sequentially arranged along the optical path; The sum frequency optical path is used to: The laser and wavelength are The laser is combined with the frequency to generate 248.3nm deep ultraviolet laser.

2. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 1, characterized in that: The triple frequency optical path is used to convert the received laser into a wavelength of Laser, output wavelength is The laser and wavelength are The laser with wavelength The laser and wavelength are After the laser is processed by frequency summation, the wavelength is of laser.

3. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 1, characterized in that: The optical parametric oscillator optical path is used to convert the received laser into a wavelength of Laser, then the wavelength is The laser is converted into a wavelength of of laser.

4. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 1, characterized in that: The triple frequency optical path comprises a first frequency doubling nonlinear optical crystal, a first sum frequency nonlinear optical crystal and a first dichroic mirror which are sequentially arranged along the optical path.

5. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 1, characterized in that: The sum frequency optical path is provided with a second sum frequency nonlinear optical crystal; the second sum frequency nonlinear optical crystal is used to receive a wavelength of The laser and wavelength are The laser is frequency combined to obtain 248.3nm deep ultraviolet laser.

6. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 5, characterized in that: A fifth dichroic mirror and a sixth dichroic mirror are arranged in sequence on the sum frequency optical path; the 248.3 nm deep ultraviolet laser is then output through the fifth dichroic mirror and the sixth dichroic mirror in sequence.

7. The 248.3 nm single-frequency all-solid-state deep ultraviolet laser system according to claim 6, characterized in that: The fifth dichroic mirror and the sixth dichroic mirror are both coated with a dielectric film, and the dielectric film reflects the laser with a wavelength of 248.3 nm and transmits Wavelength and wavelength of laser light.

8. A 248.3 nm single-frequency all-solid-state deep ultraviolet laser output method, using a 248.3 nm single-frequency all-solid-state deep ultraviolet laser system as claimed in claim 1, characterized in that: include: For wavelength The single-frequency seed laser is modulated and amplified in turn, and the amplified wavelength is The laser is split and processed into two paths; After frequency doubling and sum frequency processing, one of the channels generates a wavelength of Laser The other path is processed by frequency doubling and optical parametric oscillation to produce a wavelength of Laser Finally, the wavelength is The laser and wavelength are The laser is combined with the frequency to generate 248.3nm deep ultraviolet laser.

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