High Conversion Efficiency, High Beam Quality, High Peak Power 520 ps, 100 Hz, 2 mJ Tunable Blue All-Solid-State Laser

High Conversion Efficiency, High Beam Quality, High Peak Power 520 ps, 100 Hz, 2 mJ Tunable Blue All-Solid-State Laser | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article High Conversion Efficiency, High Beam Quality, High Peak Power 520 ps, 100 Hz, 2 mJ Tunable Blue All-Solid-State Laser Jian Yin, Yu Yu, Hengzhe Yu, Yu Zhang, Chenjie Zhao, Junguang Wang, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6278788/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract This study demonstrates a wavelength-tunable blue solid-state laser system based on a hundred-picosecond microchip laser. By utilizing a 355 nm laser to pump a beta-barium borate optical parametric oscillator (BBO-OPO), the system achieves laser output tunable across the 420–710 nm range. The output laser pulses exhibit a pulse width of 520 ps, and at a repetition rate of 100 Hz, the single-pulse energy reaches up to 2.13 mJ. The beam quality is characterized by M x 2 ​=2.433 and M y 2 =2.384, with an optical-to-optical conversion efficiency of 34.99% from the ultraviolet pump light to the blue output. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction Laser sources in the blue-green wavelength range have become indispensable in oceanographic exploration systems, including oceanographic lidar, underwater laser communication, and bathymetric laser sensing, owing to their compatibility with the optical transmission window of seawater [ 1 – 3 ]. The optimal wavelength for deep-sea applications lies within the blue spectral range of 420–510 nm, while coastal waters exhibit optimal transmission in the green range of 520–580 nm, as the spectral attenuation coefficients vary significantly across different seawater types [ 4 , 5 ]. In 2018, Ma Jian et al. achieved a significant milestone by generating 486.1 nm blue laser pulses with a pulse width of 8 ns using a 355 nm ultraviolet pulsed laser to pump a beta-barium borate (BBO) crystal-based optical parametric oscillator (OPO) [ 6 ]. This work marked the first successful demonstration of 486.1 nm blue laser pulse generation via a 355 nm-pumped OPO. By 2020, Zhu Xiaolei et al. developed a dual-wavelength blue-green laser system, delivering 486.1 nm blue and 532 nm green laser pulses with energies of 9.6 mJ and 10.6 mJ, and pulse widths of 4.5 ns and 5 ns, respectively [ 7 ]. In 2021, Zhang et al. further advanced the field by producing 486.1 nm blue laser pulses with a pulse energy of 162 mJ and a pulse width of 9.6 ns using a 355 nm-pumped BBO-OPO system [ 8 ]. Most recently, in 2022, Wang Miao et al. developed a low-threshold, singly resonant OPO with a tunable wavelength range of 410–630 nm, achieving a single-pulse energy of 62 mJ and a pulse width of 1.6 ns at 500 nm [ 9 ]. Despite these advancements, current tunable blue laser systems are limited to nanosecond pulse widths. In oceanographic lidar applications, pulse width directly impacts resolution, with narrower pulses enabling higher precision. Picosecond blue lasers, with their ultrashort pulse widths, high precision, and high peak power densities, offer significant advantages over nanosecond lasers, achieving centimeter-level resolution in lidar detection [ 10 ]. This study focuses on a microchip-pumped, all-solid-state picosecond OPO system, which boasts exceptional features such as ultrashort pulse width, high peak power, excellent beam quality, high conversion efficiency, and tunability across the 420–710 nm wavelength range. 2. Experimental Design 2.1 Simulation and Modeling The threshold estimation formula for a singly resonant optical parametric oscillator (OPO) is expressed as follows [ 11 ]: $$\:{J}_{0}=\frac{4.5{n}_{s}{n}_{i}{n}_{p}{\epsilon\:}_{0}c}{{{w}_{s}{w}_{i}{d}_{eff}^{2}l}_{s}{l}_{eff}^{2}}\frac{\tau\:}{{(1+\gamma\:)}^{2}}{\left(\frac{L}{2\tau\:}ln\frac{{P}_{n}}{{P}_{0}}+ln\frac{1}{\sqrt{R}}+ln4\right)}^{2}$$ In the formula, p , s , and i denote the pump, signal, and idler beams, respectively; n represents the refractive index; d eff​ is the effective nonlinear coefficient; L is the cavity length; l is the crystal length; and R is the reflectivity of the OPO output coupler for the signal beam. The parameter γ represents the intensity ratio of forward to backward waves passing through the nonlinear crystal. Analysis of the formula reveals that the OPO threshold is influenced by several factors, including the effective nonlinear coupling length, output coupler reflectivity, pump pulse width, absorption coefficient of the nonlinear crystal, and the spatial coupling coefficient between the pump and signal beams. Based on the OPO threshold formula, the system parameters were carefully designed. To simplify calculations, the pump beam was assumed to have a flat-top profile. The pump beam radius was set to 1.7 mm, the walk-off angle to 70.12 mrad, and the crystal length to 10 mm. To accommodate wavelength tuning and avoid efficiency degradation due to excessive cavity length, the resonator length was set to 12 mm. Figure 1 illustrates the OPO threshold as a function of the output coupler reflectivity. As the reflectivity R increases, the threshold decreases, stabilizing between 60% and 100%. Based on these results, the output coupler reflectivity was chosen to be 65%, yielding a theoretical threshold of 23.82 MW/cm². Figure 2 shows the impact of pump beam radius and peak power density on OPO gain. Larger pump beam radii result in higher gain due to improved coupling efficiency with the signal beam. However, larger radii also reduce the peak power density for a given pump power. The advantage of picosecond pulses over nanosecond pulses lies in their higher peak power density for the same energy, enabling larger beam radii and higher OPO gain. The walk-off length of the nonlinear crystal was calculated to be 25.6 mm using the formula: $$\:{l}_{\omega\:}=\frac{\sqrt{\pi\:}}{2}\frac{{\omega\:}_{p}}{\rho\:}\sqrt{\frac{{\omega\:}_{p}^{2}+{\omega\:}_{s}^{2}}{{\omega\:}_{p}^{2}+{\omega\:}_{s}^{2}/2}}$$ where ρ is the walk-off angle, and ω p ​ and ω s ​ are the pump and signal beam radii, respectively. When the crystal length is shorter than the walk-off length, it can be considered the effective gain length. Figure 3 demonstrates the effect of pump beam radius on the effective gain length in BBO crystals. As the pump beam radius increases, the effective gain length grows, slightly exceeding the crystal length for sufficiently large radii. For pump radii below 1 mm, the effective gain length is nearly independent of crystal length. Shorter crystals require smaller pump radii, necessitating a balance between peak power density and effective gain length in the experiment. Based on this analysis, a 10 mm BBO crystal was selected as the OPO gain medium. 2.2 Experimental Setup The experimental system for generating picosecond blue laser pulses is illustrated in Fig. 4 . The system comprises three main modules: (1) a 1064 nm pump source and amplifier system for generating and amplifying picosecond 1064 nm laser pulses; (2) a frequency doubling and sum-frequency generation module to produce 355 nm pump light for the OPO; and (3) a BBO-OPO module for generating tunable blue laser output in the 420–710 nm range [ 12 , 13 ]. Frequency doubling and sum-frequency generation were achieved using two LBO crystals, each measuring 8×8×10 mm³. The frequency-doubling crystal was cut at θ = 90° and φ = 11.5°, with anti-reflective coatings for 1064 nm and 532 nm. The sum-frequency crystal was cut at θ = 43° and φ = 90°, with anti-reflective coatings for 1064 nm, 532 nm, and 355 nm. A dichroic mirror (HR@355 nm & HT@1064 nm & HT@532 nm) was used to separate the 355 nm pump beam. The dichroic mirror M1 (HR@355 nm & HT@1064 nm & HT@532 nm) is positioned in front of the sum-frequency crystal. Its primary function is to reflect the 355 nm return beam out of the optical path, thereby preventing potential damage to the preceding optical components. The OPO resonator was configured as a flat-flat cavity. The input mirror featured an anti-reflective coating for 355 nm and a high-reflective coating for 420–710 nm. The output mirror, positioned close to the crystal, had a high-reflective coating for 355 nm, a partial reflective coating (65%) for 420–710 nm, and an anti-reflective coating for 710–2300 nm. The BBO crystal, with dimensions of 13×5×10 mm³, was cut at 29° and had anti-reflective coatings for 355 nm on both faces. The effective nonlinear coefficient d eff​ ​was 2.06 pm/V, and the walk-off angle was 70.2 mrad. To prevent exceeding the 100 MW/cm² damage threshold of the coatings, the pump beam radius was set to 1.75 mm. The cavity length was fixed at 12 mm. The 355 nm pump beam entered the crystal, was reflected by the OPO output mirror, and passed through the crystal again, generating signal and idler beams. The signal beam (420–710 nm) was resonated within the cavity, while the idler beam (710–2300 nm) was transmitted, achieving single resonance. Wavelength tuning was accomplished by adjusting the angle of the BBO crystal. Figure 5 shows the relationship between the output wavelength and the BBO crystal angle, as simulated using SNLO software. At a crystal angle of 29°, the output wavelength was 477 nm, corresponding to the maximum energy. The degeneracy point, where the signal and idler wavelengths both equal 710 nm, occurred at θ = 33.2°. 3. Results and Analysis The beam quality and spot profile of the 1064 nm laser were measured using a Duma Optronics M² meter and a CCD camera, as illustrated in Fig. 6 . The beam quality factors were determined to be M x 2 ​=1.192 and M y 2 ​=1.271. Figure 7 shows the beam quality and spot profile of the OPO output. The OPO output exhibited excellent fundamental mode distribution, with beam quality factors of M x 2 ​=2.433 and M y 2 =2.384, and a near-field spot diameter of 3.6 mm. The superior beam quality of the OPO output compared to the fundamental beam can be attributed to: (1) spatial filtering by the nonlinear optical effect, which preferentially converts uniform components of the pump beam; (2) mode selection by the OPO, which suppresses higher-order modes; and (3) reduced thermal effects and wavefront distortion in the OPO output due to lower absorption in the nonlinear crystal. The output energy was measured using an Ophir Optronics energy meter (Vega Pyroelectric PE50DIF-ER). The maximum energy was observed at 477 nm. Figure 8 shows the output energy and conversion efficiency of the 532 nm, 355 nm, and 477 nm lasers as a function of the 1064 nm pump energy. At a pump energy of 13.19 mJ, the maximum output energies were 8.65 mJ (532 nm), 6.08 mJ (355 nm), and 2.13 mJ (477 nm), with corresponding conversion efficiencies of 65.54%, 46.10%, and 34.99%, respectively. The increase in efficiency with pump current was attributed to a reduction in beam diameter and an increase in peak power density caused by thermal lensing. The experimental OPO threshold was measured to be 33.2 MW/cm², slightly higher than the theoretical value of 23.82 MW/cm². This discrepancy is likely due to unaccounted cavity losses and non-uniform energy distribution. The maximum conversion efficiency η of the singly resonant pulsed OPO is given by [ 8 ]: $$\:\eta\:=\frac{0.9(1-R)(\text{l}\text{n}N{)}^{2.33}}{[1-R(1-{\delta\:}_{scat}\left)\right]N}$$ where R is the output coupler reflectivity, δ scat​ is the cavity scattering loss, and N is the ratio of the pump peak power density to the threshold peak power density. Figure 9 illustrates the variation of OPO conversion efficiency with pump peak power density. The efficiency increased with pump power density but was ultimately limited by the coating damage threshold of 100 MW/cm 2 . At R = 65%, the theoretical maximum efficiency was calculated to be 37.07%, while the experimental value reached 34.99%. The discrepancy between the theoretical and experimental values can be attributed to factors such as cavity losses, thermal effects, and non-uniform energy distribution. Figure 10 displays the pulse waveforms of the 1064 nm, 355 nm, and 477 nm lasers, measured using a fast photodetector (UPD-35-UVIR-D, rise time < 35 ps) and a digital oscilloscope (DPO71254C; bandwidth: 12.5 GHz). The measured pulse widths were 700 ps for the 1064 nm laser, 640 ps for the 355 nm laser, and 520 ps for the 477 nm laser. The OPO process significantly compressed the pulse width, a result attributed to its threshold behavior. Figure 11 shows the OPO output spectrum, measured using an Ocean Optics SR4 spectrometer. By adjusting the angle of the BBO crystal, the signal wavelength could be continuously tuned from 420 nm to 710 nm. Near the degeneracy wavelength of 710 nm, the output wavelength exhibited high sensitivity to the crystal angle, making it challenging to achieve narrow-linewidth output. 4. Conclusion This study demonstrates a tunable picosecond blue laser system based on a home-built 1064 nm picosecond laser operating at a repetition rate of 100 Hz. The system features beam quality factors of M x 2 ​=1.192 and M y 2 =1.271, and delivers a pulse energy of 13.19 mJ. The 355 nm pump beam, generated through frequency doubling and sum-frequency generation, achieves an energy of 6.08 mJ. When used to pump a BBO-based optical parametric oscillator (OPO), this system produces tunable blue laser output in the 420–710 nm range, with a maximum energy of 2.13 mJ at 477 nm, a conversion efficiency of 34.99%, and beam quality factors of M x 2 ​=2.433 and M y 2 =2.384. The system offers several advantages, including a simple structure, high efficiency, narrow pulse width, high peak power, and excellent beam quality, making it well-suited for industrial, scientific, and underwater applications. To the best of our knowledge, this represents the first demonstration of a tunable picosecond blue laser system based on a 355 nm-pumped BBO-OPO. Declarations Acknowledgements This work was supported by the Opening Funding of National Key Laboratory of Electromagnetic Space Security and Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems Fund. Funding This work was supported by the Natural Science Foundation of China (Grant number: 62075056) Data availability No datasets were generated or analysed during the current study. D isclosures . The authors declare no conflicts of interest. Author Contribution J.Y. and Y.Y. conceived and designed the study. J.Y., H.Y., and Y.Z. conducted the experiments and collected the data. C.Z. and J.W. performed data analysis and interpretation. L.L. and S.D. contributed to the theoretical modeling and simulation. W.L. and K.L. assisted with experimental setup and optimization. C.C. and Y.Z. prepared the figures and tables. Z.H. and Y.W. wrote the main manuscript text. Z.L. supervised the project and provided critical revisions to the manuscript. 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Laser Physics: An International Journal devoted to Theoretical and Experimental Laser Research and Application, 2013, 23(3): 035401-1--8. Sheng Wu, Vadym Kapinus, A. Blake Geoffrey. Mixed type I and II BBO OPO pumped at 355 nm provides good beam quality, bandwidth, and efficiency [J]. California Institute of Technology (United States), 2004, 5337: 102-11. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 30 Apr, 2025 Reviews received at journal 03 Apr, 2025 Reviewers agreed at journal 30 Mar, 2025 Reviewers invited by journal 30 Mar, 2025 Editor assigned by journal 24 Mar, 2025 Submission checks completed at journal 22 Mar, 2025 First submitted to journal 21 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6278788","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":440726418,"identity":"10ac137e-cba0-4f66-b5f0-eda1a29b96c4","order_by":0,"name":"Jian Yin","email":"data:image/png;base64,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","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":true,"prefix":"","firstName":"Jian","middleName":"","lastName":"Yin","suffix":""},{"id":440726419,"identity":"fce38a0d-6aab-4d2c-b340-5c8bffc3d245","order_by":1,"name":"Yu Yu","email":"","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Yu","suffix":""},{"id":440726420,"identity":"0cad9511-bbe2-482d-92f1-8d6b6c3bbbfd","order_by":2,"name":"Hengzhe Yu","email":"","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Hengzhe","middleName":"","lastName":"Yu","suffix":""},{"id":440726421,"identity":"765f6d12-54dc-4781-a223-14cae4dcd9eb","order_by":3,"name":"Yu Zhang","email":"","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Yu","middleName":"","lastName":"Zhang","suffix":""},{"id":440726422,"identity":"ebad8531-5e0f-45db-9dc4-f607a492712b","order_by":4,"name":"Chenjie Zhao","email":"","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Chenjie","middleName":"","lastName":"Zhao","suffix":""},{"id":440726423,"identity":"75cf0524-a358-4879-bfc5-a8c27b78e8a2","order_by":5,"name":"Junguang Wang","email":"","orcid":"","institution":"China Electronics Technology Group Corporation Optoelectronics Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Junguang","middleName":"","lastName":"Wang","suffix":""},{"id":440726424,"identity":"0abde92e-e2ef-47e9-8201-2c7c0846795e","order_by":6,"name":"Liping Liu","email":"","orcid":"","institution":"China Electronics Technology Group Corporation Optoelectronics Research Institute","correspondingAuthor":false,"prefix":"","firstName":"Liping","middleName":"","lastName":"Liu","suffix":""},{"id":440726425,"identity":"ef9c8cdc-e988-47ea-9f50-9994f59ee210","order_by":7,"name":"Shanshan Dong","email":"","orcid":"","institution":"Hebei University of Technology","correspondingAuthor":false,"prefix":"","firstName":"Shanshan","middleName":"","lastName":"Dong","suffix":""},{"id":440726426,"identity":"4e579e50-b883-48a8-93cd-2354f978e748","order_by":8,"name":"Weihua Li","email":"","orcid":"","institution":"Weihai Photonics Information Technology Lab Co. 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I phase - matching of BBO crystals\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/796db4027239f1b4e2fbaac7.jpg"},{"id":81008965,"identity":"6e8e74e4-19a9-4022-b5d5-ce0e9ffdbf42","added_by":"auto","created_at":"2025-04-21 08:07:14","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":42682,"visible":true,"origin":"","legend":"\u003cp\u003eBeam quality of the 1064 nm fundamental frequency light\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/47f54f2df200eeb50cb66bd7.jpg"},{"id":81008517,"identity":"7831e099-569c-4be0-9891-d693940df96c","added_by":"auto","created_at":"2025-04-21 07:59:14","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":35650,"visible":true,"origin":"","legend":"\u003cp\u003eThe beam quality of the output from OPO\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/79877b8731d9e52490fdcb21.jpg"},{"id":81008514,"identity":"187bb0eb-fc2b-4310-8308-8019d312f8d7","added_by":"auto","created_at":"2025-04-21 07:59:14","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":42972,"visible":true,"origin":"","legend":"\u003cp\u003eThe variation curves of the single-pulse energy and conversion efficiency of the 532\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/50a686160ccd225626ddef93.jpg"},{"id":81008520,"identity":"4f990b22-1279-4f18-b379-e83e21065caf","added_by":"auto","created_at":"2025-04-21 07:59:14","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":33543,"visible":true,"origin":"","legend":"\u003cp\u003eCurve of OPO conversion efficiency versus peak power density of pump light\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/f0d325654e603b9584f3a176.jpg"},{"id":81008522,"identity":"928d07d5-16ed-474e-9937-900bcf428d5a","added_by":"auto","created_at":"2025-04-21 07:59:14","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":55367,"visible":true,"origin":"","legend":"\u003cp\u003e(a) The laser pulse waveform of 1064 nm;(b) The laser pulse waveform of 355 nm;(c) The laser pulse waveform of 477 nm\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/c25a75f4b656bbb99ed97584.jpg"},{"id":81008532,"identity":"59dff2e3-9f8b-47c9-8fd8-75bd48e34aa7","added_by":"auto","created_at":"2025-04-21 07:59:14","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":47803,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement results of the OPO output spectrum\u003c/p\u003e","description":"","filename":"11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/c6ce3e5e3d78fa1bbfafcaaf.jpg"},{"id":81012639,"identity":"0446749b-65e5-419a-bdad-665242d728e5","added_by":"auto","created_at":"2025-04-21 08:31:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":848670,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6278788/v1/fd142eaa-81ec-4b10-9400-494461be3fd7.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"High Conversion Efficiency, High Beam Quality, High Peak Power 520 ps, 100 Hz, 2 mJ Tunable Blue All-Solid-State Laser","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eLaser sources in the blue-green wavelength range have become indispensable in oceanographic exploration systems, including oceanographic lidar, underwater laser communication, and bathymetric laser sensing, owing to their compatibility with the optical transmission window of seawater [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The optimal wavelength for deep-sea applications lies within the blue spectral range of 420\u0026ndash;510 nm, while coastal waters exhibit optimal transmission in the green range of 520\u0026ndash;580 nm, as the spectral attenuation coefficients vary significantly across different seawater types [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn 2018, Ma Jian et al. achieved a significant milestone by generating 486.1 nm blue laser pulses with a pulse width of 8 ns using a 355 nm ultraviolet pulsed laser to pump a beta-barium borate (BBO) crystal-based optical parametric oscillator (OPO) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This work marked the first successful demonstration of 486.1 nm blue laser pulse generation via a 355 nm-pumped OPO. By 2020, Zhu Xiaolei et al. developed a dual-wavelength blue-green laser system, delivering 486.1 nm blue and 532 nm green laser pulses with energies of 9.6 mJ and 10.6 mJ, and pulse widths of 4.5 ns and 5 ns, respectively [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. In 2021, Zhang et al. further advanced the field by producing 486.1 nm blue laser pulses with a pulse energy of 162 mJ and a pulse width of 9.6 ns using a 355 nm-pumped BBO-OPO system [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Most recently, in 2022, Wang Miao et al. developed a low-threshold, singly resonant OPO with a tunable wavelength range of 410\u0026ndash;630 nm, achieving a single-pulse energy of 62 mJ and a pulse width of 1.6 ns at 500 nm [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite these advancements, current tunable blue laser systems are limited to nanosecond pulse widths. In oceanographic lidar applications, pulse width directly impacts resolution, with narrower pulses enabling higher precision. Picosecond blue lasers, with their ultrashort pulse widths, high precision, and high peak power densities, offer significant advantages over nanosecond lasers, achieving centimeter-level resolution in lidar detection [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This study focuses on a microchip-pumped, all-solid-state picosecond OPO system, which boasts exceptional features such as ultrashort pulse width, high peak power, excellent beam quality, high conversion efficiency, and tunability across the 420\u0026ndash;710 nm wavelength range.\u003c/p\u003e"},{"header":"2. Experimental Design","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Simulation and Modeling\u003c/h2\u003e \u003cp\u003eThe threshold estimation formula for a singly resonant optical parametric oscillator (OPO) is expressed as follows [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]:\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{J}_{0}=\\frac{4.5{n}_{s}{n}_{i}{n}_{p}{\\epsilon\\:}_{0}c}{{{w}_{s}{w}_{i}{d}_{eff}^{2}l}_{s}{l}_{eff}^{2}}\\frac{\\tau\\:}{{(1+\\gamma\\:)}^{2}}{\\left(\\frac{L}{2\\tau\\:}ln\\frac{{P}_{n}}{{P}_{0}}+ln\\frac{1}{\\sqrt{R}}+ln4\\right)}^{2}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eIn the formula, \u003cem\u003ep\u003c/em\u003e, \u003cem\u003es\u003c/em\u003e, and \u003cem\u003ei\u003c/em\u003e denote the pump, signal, and idler beams, respectively; \u003cem\u003en\u003c/em\u003e represents the refractive index; \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eeff​\u003c/em\u003e\u003c/sub\u003e is the effective nonlinear coefficient; \u003cem\u003eL\u003c/em\u003e is the cavity length; \u003cem\u003el\u003c/em\u003e is the crystal length; and \u003cem\u003eR\u003c/em\u003e is the reflectivity of the OPO output coupler for the signal beam. The parameter \u003cem\u003eγ\u003c/em\u003e represents the intensity ratio of forward to backward waves passing through the nonlinear crystal. Analysis of the formula reveals that the OPO threshold is influenced by several factors, including the effective nonlinear coupling length, output coupler reflectivity, pump pulse width, absorption coefficient of the nonlinear crystal, and the spatial coupling coefficient between the pump and signal beams.\u003c/p\u003e \u003cp\u003eBased on the OPO threshold formula, the system parameters were carefully designed. To simplify calculations, the pump beam was assumed to have a flat-top profile. The pump beam radius was set to 1.7 mm, the walk-off angle to 70.12 mrad, and the crystal length to 10 mm. To accommodate wavelength tuning and avoid efficiency degradation due to excessive cavity length, the resonator length was set to 12 mm.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e illustrates the OPO threshold as a function of the output coupler reflectivity. As the reflectivity \u003cem\u003eR\u003c/em\u003e increases, the threshold decreases, stabilizing between 60% and 100%. Based on these results, the output coupler reflectivity was chosen to be 65%, yielding a theoretical threshold of 23.82 MW/cm\u0026sup2;.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e shows the impact of pump beam radius and peak power density on OPO gain. Larger pump beam radii result in higher gain due to improved coupling efficiency with the signal beam. However, larger radii also reduce the peak power density for a given pump power. The advantage of picosecond pulses over nanosecond pulses lies in their higher peak power density for the same energy, enabling larger beam radii and higher OPO gain.\u003c/p\u003e \u003cp\u003eThe walk-off length of the nonlinear crystal was calculated to be 25.6 mm using the formula:\u003cdiv id=\"Equb\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e\n$$\\:{l}_{\\omega\\:}=\\frac{\\sqrt{\\pi\\:}}{2}\\frac{{\\omega\\:}_{p}}{\\rho\\:}\\sqrt{\\frac{{\\omega\\:}_{p}^{2}+{\\omega\\:}_{s}^{2}}{{\\omega\\:}_{p}^{2}+{\\omega\\:}_{s}^{2}/2}}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eρ\u003c/em\u003e is the walk-off angle, and \u003cem\u003eω\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e​ and \u003cem\u003eω\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e​ are the pump and signal beam radii, respectively. When the crystal length is shorter than the walk-off length, it can be considered the effective gain length.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e demonstrates the effect of pump beam radius on the effective gain length in BBO crystals. As the pump beam radius increases, the effective gain length grows, slightly exceeding the crystal length for sufficiently large radii. For pump radii below 1 mm, the effective gain length is nearly independent of crystal length. Shorter crystals require smaller pump radii, necessitating a balance between peak power density and effective gain length in the experiment. Based on this analysis, a 10 mm BBO crystal was selected as the OPO gain medium.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Experimental Setup\u003c/h2\u003e \u003cp\u003eThe experimental system for generating picosecond blue laser pulses is illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. The system comprises three main modules: (1) a 1064 nm pump source and amplifier system for generating and amplifying picosecond 1064 nm laser pulses; (2) a frequency doubling and sum-frequency generation module to produce 355 nm pump light for the OPO; and (3) a BBO-OPO module for generating tunable blue laser output in the 420\u0026ndash;710 nm range [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFrequency doubling and sum-frequency generation were achieved using two LBO crystals, each measuring 8\u0026times;8\u0026times;10 mm\u0026sup3;. The frequency-doubling crystal was cut at \u003cem\u003eθ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;90\u0026deg; and \u003cem\u003eφ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;11.5\u0026deg;, with anti-reflective coatings for 1064 nm and 532 nm. The sum-frequency crystal was cut at \u003cem\u003eθ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;43\u0026deg; and \u003cem\u003eφ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;90\u0026deg;, with anti-reflective coatings for 1064 nm, 532 nm, and 355 nm. A dichroic mirror (HR@355 nm \u0026amp; HT@1064 nm \u0026amp; HT@532 nm) was used to separate the 355 nm pump beam. The dichroic mirror M1 (HR@355 nm \u0026amp; HT@1064 nm \u0026amp; HT@532 nm) is positioned in front of the sum-frequency crystal. Its primary function is to reflect the 355 nm return beam out of the optical path, thereby preventing potential damage to the preceding optical components.\u003c/p\u003e \u003cp\u003eThe OPO resonator was configured as a flat-flat cavity. The input mirror featured an anti-reflective coating for 355 nm and a high-reflective coating for 420\u0026ndash;710 nm. The output mirror, positioned close to the crystal, had a high-reflective coating for 355 nm, a partial reflective coating (65%) for 420\u0026ndash;710 nm, and an anti-reflective coating for 710\u0026ndash;2300 nm. The BBO crystal, with dimensions of 13\u0026times;5\u0026times;10 mm\u0026sup3;, was cut at 29\u0026deg; and had anti-reflective coatings for 355 nm on both faces. The effective nonlinear coefficient \u003cem\u003ed\u003c/em\u003e\u003csub\u003e\u003cem\u003eeff​\u003c/em\u003e\u003c/sub\u003e ​was 2.06 pm/V, and the walk-off angle was 70.2 mrad.\u003c/p\u003e \u003cp\u003eTo prevent exceeding the 100 MW/cm\u0026sup2; damage threshold of the coatings, the pump beam radius was set to 1.75 mm. The cavity length was fixed at 12 mm. The 355 nm pump beam entered the crystal, was reflected by the OPO output mirror, and passed through the crystal again, generating signal and idler beams. The signal beam (420\u0026ndash;710 nm) was resonated within the cavity, while the idler beam (710\u0026ndash;2300 nm) was transmitted, achieving single resonance. Wavelength tuning was accomplished by adjusting the angle of the BBO crystal.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the relationship between the output wavelength and the BBO crystal angle, as simulated using SNLO software. At a crystal angle of 29\u0026deg;, the output wavelength was 477 nm, corresponding to the maximum energy. The degeneracy point, where the signal and idler wavelengths both equal 710 nm, occurred at \u003cem\u003eθ\u003c/em\u003e\u0026thinsp;=\u0026thinsp;33.2\u0026deg;.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results and Analysis","content":"\u003cp\u003eThe beam quality and spot profile of the 1064 nm laser were measured using a Duma Optronics M\u0026sup2; meter and a CCD camera, as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. The beam quality factors were determined to be \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=1.192 and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=1.271.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows the beam quality and spot profile of the OPO output. The OPO output exhibited excellent fundamental mode distribution, with beam quality factors of \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=2.433 and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e=2.384, and a near-field spot diameter of 3.6 mm. The superior beam quality of the OPO output compared to the fundamental beam can be attributed to: (1) spatial filtering by the nonlinear optical effect, which preferentially converts uniform components of the pump beam; (2) mode selection by the OPO, which suppresses higher-order modes; and (3) reduced thermal effects and wavefront distortion in the OPO output due to lower absorption in the nonlinear crystal.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe output energy was measured using an Ophir Optronics energy meter (Vega Pyroelectric PE50DIF-ER). The maximum energy was observed at 477 nm. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the output energy and conversion efficiency of the 532 nm, 355 nm, and 477 nm lasers as a function of the 1064 nm pump energy. At a pump energy of 13.19 mJ, the maximum output energies were 8.65 mJ (532 nm), 6.08 mJ (355 nm), and 2.13 mJ (477 nm), with corresponding conversion efficiencies of 65.54%, 46.10%, and 34.99%, respectively. The increase in efficiency with pump current was attributed to a reduction in beam diameter and an increase in peak power density caused by thermal lensing.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe experimental OPO threshold was measured to be 33.2 MW/cm\u0026sup2;, slightly higher than the theoretical value of 23.82 MW/cm\u0026sup2;. This discrepancy is likely due to unaccounted cavity losses and non-uniform energy distribution.\u003c/p\u003e \u003cp\u003eThe maximum conversion efficiency \u003cem\u003eη\u003c/em\u003e of the singly resonant pulsed OPO is given by [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]:\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\:\\eta\\:=\\frac{0.9(1-R)(\\text{l}\\text{n}N{)}^{2.33}}{[1-R(1-{\\delta\\:}_{scat}\\left)\\right]N}$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eR\u003c/em\u003e is the output coupler reflectivity, \u003cem\u003eδ\u003c/em\u003e\u003csub\u003e\u003cem\u003escat​\u003c/em\u003e\u003c/sub\u003e is the cavity scattering loss, and \u003cem\u003eN\u003c/em\u003e is the ratio of the pump peak power density to the threshold peak power density. Figure\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e illustrates the variation of OPO conversion efficiency with pump peak power density. The efficiency increased with pump power density but was ultimately limited by the coating damage threshold of 100 MW/cm\u003csup\u003e2\u003c/sup\u003e. At \u003cem\u003eR\u003c/em\u003e\u0026thinsp;=\u0026thinsp;65%, the theoretical maximum efficiency was calculated to be 37.07%, while the experimental value reached 34.99%. The discrepancy between the theoretical and experimental values can be attributed to factors such as cavity losses, thermal effects, and non-uniform energy distribution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e displays the pulse waveforms of the 1064 nm, 355 nm, and 477 nm lasers, measured using a fast photodetector (UPD-35-UVIR-D, rise time\u0026thinsp;\u0026lt;\u0026thinsp;35 ps) and a digital oscilloscope (DPO71254C; bandwidth: 12.5 GHz). The measured pulse widths were 700 ps for the 1064 nm laser, 640 ps for the 355 nm laser, and 520 ps for the 477 nm laser. The OPO process significantly compressed the pulse width, a result attributed to its threshold behavior.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e shows the OPO output spectrum, measured using an Ocean Optics SR4 spectrometer. By adjusting the angle of the BBO crystal, the signal wavelength could be continuously tuned from 420 nm to 710 nm. Near the degeneracy wavelength of 710 nm, the output wavelength exhibited high sensitivity to the crystal angle, making it challenging to achieve narrow-linewidth output.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study demonstrates a tunable picosecond blue laser system based on a home-built 1064 nm picosecond laser operating at a repetition rate of 100 Hz. The system features beam quality factors of \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=1.192 and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e=1.271, and delivers a pulse energy of 13.19 mJ. The 355 nm pump beam, generated through frequency doubling and sum-frequency generation, achieves an energy of 6.08 mJ. When used to pump a BBO-based optical parametric oscillator (OPO), this system produces tunable blue laser output in the 420\u0026ndash;710 nm range, with a maximum energy of 2.13 mJ at 477 nm, a conversion efficiency of 34.99%, and beam quality factors of \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=2.433 and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e=2.384. The system offers several advantages, including a simple structure, high efficiency, narrow pulse width, high peak power, and excellent beam quality, making it well-suited for industrial, scientific, and underwater applications. To the best of our knowledge, this represents the first demonstration of a tunable picosecond blue laser system based on a 355 nm-pumped BBO-OPO.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003eThis work was supported by the Opening Funding of National Key Laboratory of Electromagnetic Space Security and Tianjin Key Laboratory of Optoelectronic Detection Technology and Systems Fund.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003eThis work was supported by the Natural Science Foundation of \u0026nbsp; China (Grant number: 62075056)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003eNo datasets were generated or analysed during the current study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eD\u003c/strong\u003e\u003cstrong\u003eisclosures\u003c/strong\u003e\u003cstrong\u003e.\u0026nbsp;\u003c/strong\u003eThe authors declare no conflicts of interest.\u0026nbsp;\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eJ.Y. and Y.Y. conceived and designed the study. J.Y., H.Y., and Y.Z. conducted the experiments and collected the data. C.Z. and J.W. performed data analysis and interpretation. L.L. and S.D. contributed to the theoretical modeling and simulation. W.L. and K.L. assisted with experimental setup and optimization. C.C. and Y.Z. prepared the figures and tables. Z.H. and Y.W. wrote the main manuscript text. Z.L. supervised the project and provided critical revisions to the manuscript. All authors reviewed and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHang Liu, Peng Chen, Zhihua Mao, Delu Pan, Yan He. Subsurface plankton layers observed from airborne lidar in Sanya Bay, South China Sea [J]. Optics express, 2018, 26(22): 29134-47.\u003c/li\u003e\n\u003cli\u003eK. Rumbaugh Luke, J. Dunn Kaitlin, M. Bollt Erik, Brandon Cochenour, D. Jemison William. An underwater chaotic lidar sensor based on synchronized blue laser diodes [J]. Clarkson Univ (United States);Naval Air Warfare Ctr Aircraft Div (United States);US Naval Research Lab (United States);The Univ of Southern Mississippi (United States), 2016, 9827: 98270I-I-11.\u003c/li\u003e\n\u003cli\u003eLiu Dong, Chen Peng, Che Haochi, Liu Zhipeng, Liu Qun, Song Qingjun, Chen Sijie, Xu Peituo, Zhou Yudi, Chen Weibiao, Han Bing, Zhu Xiaolei, He Yan, Mao Zhihua, Le Chengfeng. Lidar Remote Sensing of Seawater Optical Properties: Experiment and Monte Carlo Simulation [J]. IEEE Trans Geoscience and Remote Sensing, 2019, 57(11): 9489-98.\u003c/li\u003e\n\u003cli\u003eLiu Qun, Liu Chong, Zhu Xiaolei, Zhou Yudi, Le Chengfeng, Bai Jian, He Yan, Bi Decang, Liu Dong. Analysis of the optimal operating wavelength of spaceborne oceanic lidar [J]. Chinese Optics, 2020, 13(1): 148-55.\u003c/li\u003e\n\u003cli\u003eChen Shuguo, Xue Cheng, Zhang Tinglu, Hu Lianbo, Chen Ge, Tang Junwu. Analysis of the Optimal Wavelength for Oceanographic Lidar at the Global Scale Based on the Inherent Optical Properties of Water [J]. Remote Sensing, 2019, 11(22): 2705-.\u003c/li\u003e\n\u003cli\u003eMa Jian Ma Jian, Lu Tingting Lu Tingting, Zhu Xiaolei Zhu Xiaolei, Ma Xiuhua Ma Xiuhua, Li Shiguang Li Shiguang, Zhou Tianhua Zhou Tianhua, Chen Weibiao Chen Weibiao. Highly efficient H-\u0026beta; Fraunhofer line optical parametric oscillator pumped by a single-frequency 355 nm laser [J]. Chinese Optics Letters, 2018, 16(8): 081901-.\u003c/li\u003e\n\u003cli\u003eJian Ma, Tingting Lu, Yan He, Zhengyang Jiang, Chunhe Hou, Kaipeng Li, Fanghua Liu, Xiaolei Zhu, Weibiao Chen. Compact dual-wavelength blue-green laser for airborne ocean detection lidar [J]. Applied optics, 2020, 59(10): C87-C91.\u003c/li\u003e\n\u003cli\u003eJiale Zhang, Jian Ma, Tingting Lu, Jianlei Wang, Xiaolei Zhu, Weibiao Chen. 16.9 MW, efficient 486.1 nm blue optical parametric oscillator using single BBO crystal [J]. Laser Physics Letters, 2021, 18(2): 025001-.\u003c/li\u003e\n\u003cli\u003eMiao Wang, Jian Ma, Tingting Lu, Shanjiang Hu, Xiaolei Zhu, Weibiao Chen. Development of single-resonant optical parametric oscillator with tunable output from 410 nm to 630 nm [J]. Chinese Optics Letters, 2022, 20(02): 85-9.\u003c/li\u003e\n\u003cli\u003eJ. Kilmer, A. Iadevaia, Y. Yin. Laser sources for lidar applications [J]. Photonics Industries International, Inc (United States), 2012, 8379: 837912--14.\u003c/li\u003e\n\u003cli\u003eBrosnan S Byer R. Optical parametric oscillator threshold and linewidth studies [J]. 1979, (15(6)): 415-31.\u003c/li\u003e\n\u003cli\u003eAkbari R, Major A. Optical, spectral and phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillation in the visible and near-infrared wavelength ranges [J]. Laser Physics: An International Journal devoted to Theoretical and Experimental Laser Research and Application, 2013, 23(3): 035401-1--8.\u003c/li\u003e\n\u003cli\u003eSheng Wu, Vadym Kapinus, A. Blake Geoffrey. Mixed type I and II BBO OPO pumped at 355 nm provides good beam quality, bandwidth, and efficiency [J]. California Institute of Technology (United States), 2004, 5337: 102-11.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"applied-physics-b","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aphb","sideBox":"Learn more about [Applied Physics B](http://link.springer.com/journal/340)","snPcode":"340","submissionUrl":"https://submission.nature.com/new-submission/340/3","title":"Applied Physics B","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-6278788/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6278788/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study demonstrates a wavelength-tunable blue solid-state laser system based on a hundred-picosecond microchip laser. By utilizing a 355 nm laser to pump a beta-barium borate optical parametric oscillator (BBO-OPO), the system achieves laser output tunable across the 420\u0026ndash;710 nm range. The output laser pulses exhibit a pulse width of 520 ps, and at a repetition rate of 100 Hz, the single-pulse energy reaches up to 2.13 mJ. The beam quality is characterized by \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ex\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e​=2.433 and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u003csup\u003e2\u003c/sup\u003e=2.384, with an optical-to-optical conversion efficiency of 34.99% from the ultraviolet pump light to the blue output.\u003c/p\u003e","manuscriptTitle":"High Conversion Efficiency, High Beam Quality, High Peak Power 520 ps, 100 Hz, 2 mJ Tunable Blue All-Solid-State Laser","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-21 07:59:09","doi":"10.21203/rs.3.rs-6278788/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-04-30T13:48:53+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-03T06:58:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"125768061025979579640835083627818926726","date":"2025-03-31T02:07:27+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-30T15:24:17+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-24T09:23:22+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-22T07:22:28+00:00","index":"","fulltext":""},{"type":"submitted","content":"Applied Physics B","date":"2025-03-21T15:06:47+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"applied-physics-b","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"aphb","sideBox":"Learn more about [Applied Physics B](http://link.springer.com/journal/340)","snPcode":"340","submissionUrl":"https://submission.nature.com/new-submission/340/3","title":"Applied Physics B","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"4bd46e6b-e823-4ae9-a1e7-5ab159b7cb33","owner":[],"postedDate":"April 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2025-05-07T13:38:19+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-21 07:59:09","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6278788","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6278788","identity":"rs-6278788","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}