High-power deep ultraviolet laser
By employing beam splitting and combining techniques and fiber coupling in deep ultraviolet lasers, combined with specific crystal and coating designs, the problems of easy damage to optical components and poor spot quality have been solved, achieving stable output of high-power deep ultraviolet lasers and improving the stability and output power of the laser.
Patent Information
- Application Number
- CN202520613518.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-02
- Publication Date
- 2026-02-24
- Estimated Expiration
- 2035-04-02
AI Technical Summary
Existing deep ultraviolet lasers suffer from problems such as easy damage to optical components, poor spot quality and low output power due to the detachment of the frequency doubling crystal in the cavity, which limits their widespread application in fields such as semiconductor wafer inspection and material property research.
The pump light is split into two beams using a beam splitter, which generate target light through two resonant cavities respectively. The target light is then combined into one beam by a beam combiner. The pump light is transmitted using fiber optic coupling to optimize the spot quality. LBO or BBO crystals are used for frequency doubling. Specific resonant cavity structures and optical element coating systems are designed to improve the stability of optical elements and the output power of deep ultraviolet laser.
It improves the stability and lifespan of the laser, increases the output power of the deep ultraviolet laser, meets the needs of high-power deep ultraviolet lasers, and solves the problems of easy damage to optical components and poor spot quality.
Smart Images
Figure CN223942206U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of laser technology, and in particular to a high-power deep ultraviolet laser. Background Technology
[0002] Deep ultraviolet (DUV) lasers have significant applications in semiconductor wafer inspection and materials property research. However, existing DUV lasers suffer from numerous problems, such as easy damage to optical components, poor spot quality due to detachment of the intracavity frequency doubling crystal, and low output power, which severely limit their widespread application in related fields. Utility Model Content
[0003] The purpose of this invention is to solve the problems existing in the prior art and to propose a high-power deep ultraviolet laser.
[0004] To achieve the above objectives, this utility model adopts the following technical solution: a high-power deep ultraviolet laser, comprising a pump source for emitting pump light, a beam splitter for splitting the pump light into two beams, two resonant cavities for receiving the split pump light respectively, each resonant cavity including an input mirror, a total reflection mirror, and an output mirror, wherein the input mirror, total reflection mirror, and output mirror form a V-shaped cavity structure within the same resonant cavity, a laser crystal located between the input mirror and the output mirror and having an anti-reflection coating on its surface that matches the wavelength of the fundamental frequency light, a frequency doubling crystal located between the total reflection mirror and the output mirror and having an anti-reflection coating on its surface that combines the fundamental frequency light and the target deep ultraviolet light, a beam combiner for combining the deep ultraviolet lasers output from the two resonant cavities into one beam, a filter and a second reflector for filtering out the fundamental frequency light and residual pump light, and a first reflector for reflecting one of the pump light beams into one of the resonant cavities.
[0005] Preferably, the input mirror is divided into input mirror one and input mirror two, the total reflection mirror is divided into total reflection mirror one and total reflection mirror two, the output mirror is divided into output mirror one and output mirror two, the laser crystal is divided into laser crystal one and laser crystal two, and the frequency doubling crystal is divided into frequency doubling crystal one and frequency doubling crystal two. The input mirror one, total reflection mirror one, output mirror one, laser crystal one and frequency doubling crystal one are located in one of the resonant cavities, and the input mirror two, total reflection mirror two, output mirror two, laser crystal two and frequency doubling crystal two are located in another resonant cavity.
[0006] Preferably, the input mirror and the total reflection mirror are flat mirrors, and the output mirror is a concave mirror.
[0007] Preferably, the frequency doubling crystal can be an LBO or BBO crystal.
[0008] Preferably, the pump light source is transmitted via optical fiber coupling.
[0009] Preferably, it also includes a focusing lens, a first focusing lens, and a second focusing lens. The focusing lens is used to focus the pump light emitted by the pump light source, and the first focusing lens and the second focusing lens are used to focus the two beams split by the beam splitting device, respectively.
[0010] Compared with the prior art, the advantages and positive effects of this utility model are as follows:
[0011] 1. In this utility model, by setting up a beam splitting device, two resonant cavities and a beam combiner, the pump light is split into two beams by the beam splitting device, and the target light is generated in the two resonant cavities respectively. Then, the two laser beams are combined into one beam by the beam combiner, which reduces the laser energy borne by a single optical element, reduces the risk of optical elements being damaged due to excessive energy, and improves the stability and service life of the laser.
[0012] 2. In this invention, by using fiber optic coupling to transmit pump light and optimizing the spot quality focused on the surface of the laser crystal, the pump light can more efficiently excite the laser crystal to generate fundamental frequency light, thereby improving the output power of the deep ultraviolet laser and meeting the demand for high-power deep ultraviolet lasers. Attached Figure Description
[0013] Figure 1 This invention provides an optical path diagram for a high-power deep ultraviolet laser.
[0014] Legend: 1. Pump source; 2. Focusing lens; 3. Beam splitter; 4. Mirror 1; 5. Focusing lens 1; 6. Input lens 1; 7. Laser crystal 1; 8. Total reflection mirror 1; 9. Frequency doubling crystal 1; 10. Output mirror 1; 11. Filter; 12. Beam combiner; 13. Mirror 2; 14. Output mirror 2; 15. Frequency doubling crystal 2; 16. Total reflection mirror 2; 17. Laser crystal 2; 18. Input lens 2; 19. Focusing lens 2. Detailed Implementation
[0015] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.
[0016] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the present invention is not limited to the specific embodiments disclosed in the following specification.
[0017] like Figure 1As shown, a high-power deep ultraviolet laser includes a pump source 1 for emitting pump light, a beam splitter 3 for splitting the pump light into two beams, and two resonant cavities for receiving the split pump light. Each resonant cavity includes an input mirror, a total reflection mirror, and an output mirror. Within the same resonant cavity, the input mirror, total reflection mirror, and output mirror form a V-shaped cavity structure. A laser crystal is located between the input mirror and the output mirror, and its surface is coated with an anti-reflection film matching the wavelength of the fundamental frequency light. A frequency doubling crystal is located... Between the total reflection mirror and the output mirror, an anti-reflection coating is coated on its surface to combine the fundamental frequency light and the target deep ultraviolet light. A beam combiner 12 is used to combine the deep ultraviolet lasers output from the two resonant cavities into one beam. A filter 11 and a second reflector 13 are used to filter out the fundamental frequency light and residual pump light. A first reflector 4 is used to reflect one of the pump light beams into one of the resonant cavities. Input mirrors are divided into input mirror 6 and input mirror 18. Total reflection mirrors are divided into total reflection mirror 8 and total reflection mirror 16. Output mirrors are divided into output mirror 1. The system includes an input mirror 16, a total reflection mirror 16, an output mirror 14, a laser crystal 7, a laser crystal 2 17, a frequency doubling crystal 9, and a frequency doubling crystal 2 15. The input mirror 16, the total reflection mirror 8, the output mirror 10, the laser crystal 7, and the frequency doubling crystal 9 are located in one resonant cavity, while the input mirror 2 18, the total reflection mirror 2 16, the output mirror 2 14, the laser crystal 2 17, and the frequency doubling crystal 2 15 are located in another resonant cavity. The input mirror and the total reflection mirror are flat mirrors, and the output mirror is a concave mirror. The coating systems of the input mirror, the total reflection mirror, and the output mirror are configured according to the target output wavelength. The frequency doubling crystal can be an LBO or BBO crystal. The pump source 1 is transmitted via fiber coupling, and the spot quality focused onto the laser crystal surface is optimized by fiber coupling. The system also includes a focusing mirror 2, a focusing mirror 5, and a focusing mirror 2 19. The focusing mirror 2 is used to focus the pump light emitted by the pump source 1, and the focusing mirrors 5 and 2 19 are used to focus the two beams split by the beam splitter 3.
[0018] In this technical solution, the pump light source 1 emits blue pump light with a center wavelength of 444nm. After being collimated by the focusing mirror 2, it reaches the beam splitting device 3 (a 45° semi-transparent and semi-reflective mirror can be used). The beam splitting device 3 splits the pump light into two beams. One beam is reflected by the reflecting mirror 4 and focused by the focusing mirror 5, and then directed to the input mirror 6 to enter one of the resonant cavities. The other beam is focused by the focusing mirror 19 and directed to the input mirror 18 to enter another resonant cavity.
[0019] In each resonant cavity, the pump light enters and illuminates the laser crystal. Taking laser crystal 7 as an example, it is selected as 0.3at.%Pr:YLF, 2mm×2mm×10mm, a-tangential, and coated with an antireflection film that matches the wavelength of the fundamental frequency light. The pump light excites the laser crystal to generate fundamental frequency light. The fundamental frequency light propagates in the resonant cavity and first reaches the output mirror 10 (concave mirror). The output mirror 10 reflects the fundamental frequency light, which then propagates to the frequency doubling crystal 9. The frequency doubling crystal 9 can be LBO (for 320nm output) or BBO (for 261nm output). Part of the fundamental frequency light is converted into deep ultraviolet light in the frequency doubling crystal 9.
[0020] Next, the mixed light containing fundamental frequency light and deep ultraviolet light propagates to total reflection mirror 8, which reflects the mixed light. The mixed light then passes through frequency doubling crystal 9, further increasing the proportion of deep ultraviolet light, and then returns to output mirror 10. At this time, output mirror 10 transmits deep ultraviolet light and reflects fundamental frequency light. The reflected fundamental frequency light is then reflected by input mirror 6 and returns to output mirror 10. This cycle continues, continuously enhancing the output of deep ultraviolet light.
[0021] Finally, the deep ultraviolet light generated by the two resonant cavities is filtered by the filter 11 and the mirror 13 to remove the fundamental frequency light and the residual pump light. Furthermore, the deep ultraviolet light is reflected by the mirror 13 so that one of the deep ultraviolet beams is perpendicular to the other. Finally, they are combined into one beam at the beam combiner 12 (which can be a Glan prism) to achieve high-power deep ultraviolet laser output.
[0022] By using fiber optic coupling to transmit pump light, the quality of the light spot focused on the laser crystal surface is optimized, and the output power is improved. At the same time, by combining two laser beams into one through a two-in-one scheme, the problem of easy damage to optical components in deep ultraviolet lasers is solved.
[0023] Furthermore, by selecting the resonant cavity structure, optical element coating system, and frequency doubling crystal, stable output of high-power deep ultraviolet lasers at different wavelengths (320nm and 261nm) was achieved. The specific implementation method is as follows:
[0024] When the resonant cavity is configured to output 320nm laser, its coating system satisfies the following: input mirror and total reflection mirror: 444nm anti-reflection, 640nm high reflection, 320nm high reflection; output mirror: 444nm anti-reflection, 640nm high reflection, 320nm high transmission; the frequency doubling crystal is an LBO crystal with a cutting angle of (90°, 53.63°).
[0025] When the resonant cavity is configured to output 261nm laser, its coating system satisfies the following: input mirror and total reflection mirror: 444nm anti-reflection, 522nm high reflection, 261nm high reflection; output mirror: 444nm anti-reflection, 522nm high reflection, 261nm high transmission; the frequency doubling crystal is a BBO crystal with a cutting angle of (48.95°, 0°).
[0026] Working principle: The pump light emitted by the pump light source is collimated by the focusing lens 2 and then split into two beams by the beam splitter 3. One beam is reflected by the reflecting mirror 4 and focused by the focusing lens 5 before entering one resonant cavity, while the other beam is focused by the focusing lens 19 before entering another resonant cavity.
[0027] Taking a resonant cavity containing an input mirror 6, a total reflection mirror 8, an output mirror 10, a laser crystal 7, and a frequency doubling crystal 9 as an example, in this resonant cavity, the pump light excites the laser crystal 7 to generate fundamental frequency light. The fundamental frequency light is reflected by the output mirror 10 to the frequency doubling crystal 9, where it is partially converted into deep ultraviolet light. The mixed light containing the fundamental frequency light and deep ultraviolet light is reflected by the total reflection mirror 8 and then passes through the frequency doubling crystal 9 again to increase the proportion of deep ultraviolet light before returning to the output mirror 10. The output mirror 10 transmits deep ultraviolet light and reflects the fundamental frequency light to the surface of the input mirror 6. The fundamental frequency light is reflected by the input mirror 6 and recycled to enhance the output of deep ultraviolet light.
[0028] The deep ultraviolet light generated by the two resonant cavities is filtered by filter 11 and mirror 13 to remove the fundamental frequency light and residual pump light, and then combined into a single output beam at the beam combiner 12.
[0029] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution of the present utility model shall still fall within the protection scope of the present utility model.
Claims
1. A high-power deep ultraviolet laser, characterized in that: The system includes a pump source (1) for emitting pump light, a beam splitter (3) for splitting the pump light into two beams, two resonant cavities for receiving the split pump light, each resonant cavity including an input mirror, a total reflection mirror and an output mirror, the input mirror, the total reflection mirror and the output mirror forming a V-shaped cavity structure within the same resonant cavity, a laser crystal located between the input mirror and the output mirror and its surface coated with an anti-reflection film matching the wavelength of the fundamental frequency light, a frequency doubling crystal located between the total reflection mirror and the output mirror and its surface coated with an anti-reflection film for the fundamental frequency light and the target deep ultraviolet light, a beam combiner (12) for combining the deep ultraviolet laser output from the two resonant cavities into one beam, a filter (11) and a second reflector (13) for filtering out the fundamental frequency light and residual pump light, and a first reflector (4) for reflecting one of the pump light beams into one of the resonant cavities.
2. The high-power deep ultraviolet laser according to claim 1, characterized in that: The input mirror is divided into input mirror one (6) and input mirror two (18), the total reflection mirror is divided into total reflection mirror one (8) and total reflection mirror two (16), the output mirror is divided into output mirror one (10) and output mirror two (14), the laser crystal is divided into laser crystal one (7) and laser crystal two (17), and the frequency doubling crystal is divided into frequency doubling crystal one (9) and frequency doubling crystal two (15). The input mirror one (6), total reflection mirror one (8), output mirror one (10), laser crystal one (7) and frequency doubling crystal one (9) are located in one of the resonant cavities, and the input mirror two (18), total reflection mirror two (16), output mirror two (14), laser crystal two (17) and frequency doubling crystal two (15) are located in another resonant cavity.
3. The high-power deep ultraviolet laser according to claim 1, characterized in that: The input mirror and total reflection mirror are flat mirrors, while the output mirror is a concave mirror.
4. The high-power deep ultraviolet laser according to claim 1, characterized in that: LBO or BBO crystals can be used for frequency doubling.
5. The high-power deep ultraviolet laser according to claim 1, characterized in that: The pump light source (1) is transmitted via optical fiber coupling.
6. The high-power deep ultraviolet laser according to claim 1, characterized in that: It also includes a focusing lens (2), a first focusing lens (5), and a second focusing lens (19). The focusing lens (2) is used to collimate the pump light emitted by the pump light source (1), and the first focusing lens (5) and the second focusing lens (19) are used to collimate the two beams split by the beam splitting device (3).