Single longitudinal mode 486.1 nm wavelength laser generation from β-Ba2BO4 -optical parametric amplifier system for ocean detection

Single longitudinal mode 486.1 nm wavelength laser generation from β-Ba2BO4 -optical parametric amplifier system for ocean detection | 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 Single longitudinal mode 486.1 nm wavelength laser generation from β-Ba 2 BO 4 -optical parametric amplifier system for ocean detection Qihui Luo, Jian Ma, Zizheng Huang, Tingting Lu, Junxuan Zhang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5826037/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 14 Mar, 2025 Read the published version in Applied Physics B → Version 1 posted 11 You are reading this latest preprint version Abstract A single longitudinal mode (SLM) 486.1 nm blue pulsed laser was investigated by adopting a single-frequency distributed feedback laser (DFB) injected optical parametric oscillator (OPO) and optical parametric amplifier (OPA) structure, pumped by a 355 nm ultraviolet SLM laser at pulse repetition rate of 200 Hz. The maximum output pulse energy of 22.0 mJ was obtained from this injection seeded OPO/OPA system, corresponding to energy extraction efficiency of 35.4% and peak power density of 46.4 MW/cm 2 . The central wavelength of output laser pulse was 486.134 nm, which was well matched the H-β Fraunhofer line of solar spectrum, and the detected spectral linewidth was around 120 MHz. blue laser optical parametric amplifier optical parametric oscillator single longitudinal mode Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Blue-green wave band is known as the optical transmission window of ocean water because its attenuation coefficient in water is significantly lower than other wave bands [ 1 , 2 ] , so that the all-solid-state blue-green laser has been widely used in ocean detection lidar, underwater wireless optical communication, laser mapping system and so on [ 3 , 4 ] . For clear pelagic water, blue laser emitting within 420 nm-490 nm is considered the optimal source for ocean detection lidar. In 2019, Liu et al. [ 5 ] demonstrated that 486.1 nm was the optimal transmitter wavelength for spaceborne ocean lidar. Since solar spectrum contains a H-β Fraunhofer line at 486.134 nm (0.14 nm bandwidth), it is believed that utilizing this H-β Fraunhofer line as the working wavelength can significantly improve the signal-to-noise ratio (SNR) for marine detection, so that this kind of ocean lidar and underwater wireless optical communication systems can work effectively in daytime with sunlight background [ 6 , 7 ] . The primarily methods for obtaining blue laser output involve Pr 3+ doped crystal laser [ 8 , 9 ] , Raman frequency shift technique [ 10 , 11 ] and nonlinear frequency conversion [ 12 – 15 ] . The blue laser source based on nonlinear frequency conversion can obtain higher peak power than the other two methods, which is more suitable for ocean lidar application. Till now, an optical parametric oscillator (OPO) pumped by 355 nm ultraviolet laser is an effective way to obtain blue laser output, which has advantages of high repetition rate, high output peak power, high beam quality and wavelength tunable, these characteristics make it an excellent laser source for ocean lidar. [ 16 – 19 ] In 2018, Rao et al. [ 14 ] achieved tunable signal output within 490 nm to 630 nm at 5 kHz repetition rate from a type-I phase matching β-Ba 2 BO 4 (BBO)-OPO system, the maximum output power was 3.23 W, and spectral linewidth increased from 0.2 nm to 0.5 nm with signal wavelength increasing. From a type-II BBO-OPO system, continuous tunable output from 490 nm to 590 nm with linewidth of 0.15 nm was achieved at a repetition rate of 2 kHz. In 2021, by inserting a Fabry-Perot etalon (F-P) in the OPO cavity, they achieved tunable single longitudinal mode (SLM) laser output in the range of 500 nm to 600 nm, the optical conversion efficiency was around 4.1% with 62 mW output power, and the average spectral linewidth was less than 250 MHz [ 15 ] . Recent years, research works on lasers emitting at the dark line of solar spectrum have been boosted, in 2018, Ma et al. [ 16 ] demonstrated a 486.1 nm blue laser output with a maximum pulse energy of 62 mJ from a BBO-OPO unit, the spectrum linewidth was less than 0.1 nm, and the peak output power was up to 7.7 MW. In 2020, a compact BBO-OPO system with 9.6 mJ blue pulse energy output at 100 Hz repetition rate was successfully equipped in a home-made airborne ocean detection lidar, but its spectral linewidth reached to about 0.3 nm [ 17 ] . Although up to 162 mJ blue pulse energy could be obtained from a BBO-OPO system, the spectral linewidth was typically more than 0.34 nm [ 18 ] , which was wider than the linewidth of solar H-β line. It can be found that a major limitation of those studies is that fails to maintain narrow-linewidth characteristics with high pulse energy output simultaneously. This makes it limited in applications, such as ocean lidar with high spectral resolution requirements. With the rapid developing of ocean remote sensing technology, the requirements for blue laser as the transmitter source are constantly improving. It has become a key problem to be solved urgently for obtaining blue pulse laser with high energy and high peak power with reasonable narrow spectral linewidth. Injection seeded OPO has been proven an effectively method to narrow OPO signal light linewidth, but the effect of seed injection will become worse in the case of high energy pumping. Therefore, it is difficult to realize high energy pulse output with narrow-linewidth just basing OPO. There have been some previous works obtained high-energy infrared laser output from an OPO/OPA hybrid structure [ 20 – 22 ] . Even more, when an injection seeded OPO with narrow-linewidth was used as the signal for OPA, and finally higher energy pulse with narrow-linewidth could be achieved [ 23 – 25 ] . However, to the best of our knowledge, blue SLM signal wave amplified by this kind of OPO/OPA system has not been reported yet. In this paper, we demonstrated a SLM 486.1 nm blue pulse laser based on a single-frequency seed injection OPO/OPA system. Pumped by a home-made 355 nm SLM pulse laser at a repetition rate of 200 Hz, output 486.1 nm pulse energy of 22.0 mJ was obtained with the maximum pump pulse energy of 60.3 mJ, corresponding to an extraction efficiency of 35.4%. The peak power density of output blue laser pulse was 46.4 MW/cm 2 , and the beam quality factor of M 2 was less than 2.3. The central wavelength was 486.134 nm with spectral linewidth of 120 MHz. This SLM and high-peak power blue pulsed laser has the potential of improving the detection performance of ocean lidar and realizing high spectral resolution detection. 2. Experimental Setup The schematic diagram of the SLM 486.1 nm blue pulsed laser was shown in Fig. 1 . The 1064 nm SLM fiber laser consisted of a continuous wave output non-planar ring oscillator (NPRO) seed laser, an acousto-optic modulator (AOM) acted as chopper, and two stages of fiber amplifiers. The pulse output from this 1064 nm SLM fiber laser was split two by a 1×2 Polarization Maintaining Tap Isolator (PMTI), and then coupled into the OPO and OPA fiber amplifiers respectively. The 355 nm laser for OPO was composed of one stage Nd:YAG rod amplifier and a tripling frequency module. The 355 nm laser for OPA was composed of a three-stage Nd:YAG rod amplifier and a tripling frequency module. The maximum 355 nm pump pulse energy for OPA was around 60.3 mJ, and that for OPO was about 4.2 mJ. The 486.1 nm seed was a SLM continuous wave laser obtained from a 972.2 nm distributed feedback laser (DFB) by a PPLN frequency doubling module. The 486.1 nm seed laser and 355 nm pump laser passed through the beam combiner M1, then entered the four-mirror ring cavity of OPO, which was a plane-plane resonator with total cavity length of 230 mm. The input mirror was also act as the output coupling mirror (OC), which was anti-reflection (AR) coated at 355 nm and 1313 nm, and partly reflection coated at 486 nm with transmission of 30%. The mirror M2 was also anti-reflection (AR) coated at 355 nm and 1313 nm, and high-reflection (HR) coated at 486 nm. And the other two cavity mirrors were high-reflection (HR) coated at 486 nm. In this OPO cavity, two 5 mm × 5 mm × 10 mm type-I phase matching BBO crystals, cut at θ = 29.6°, ϕ = 90°, were inserted between the OC and M2 as parametric medium. Similar to our previous work [ 26 ] , these two BBO crystals were placed symmetrically with respect to the pump beam axis to compensate the walk-off effect. The 486.1 nm signal laser beam from OPO was coupled into the OPA unit after passing through a beam expander with the power loss of 6%. The beam expander was designed to make the beam waist of the signal laser match the 355 nm pump beam waist inside the BBO crystals of OPA, which was helpful to improve the conversion efficiency of OPA. In experiment, the 355 nm pump lasers for OPA and OPO were homologous in time, but, due to the existence of signal pulse establishing time inside OPO, the signal output from OPO had a certain delay relative to the pump pulse, this extra delay should be offset by connecting a suitable length of fiber for the OPA fiber amplifier, shown in Fig. 1 . Figure 2 was the simulated curve of the amplified signal pulse energy as the function of the crystal length by the SNLO software, it revealed that the amplified signal pulse energy from OPA increased firstly and then decreased with the increase of crystal length due to the reverse transcription process occured. The maximum value of amplified pulse energy in Fig. 2 occurred at the OPA crystal length of about 30 mm. Therefore, in this experiment, the total length of the parameter crystals was designated according to this simulation result. The OPO signal laser beam and the 355 nm pump laser beam for OPA were coupled into BBO crystals by M3. Thess two BBO crystals were both 15 mm in length with cross-section of 10 mm × 10 mm, cut at θ = 29.6°, ϕ = 90° (type-I phase matching) and set symmetrically with respect to the pump laser beam axis to compensate the walk-off effect. 3. Results and Discussion In this blue pulsed laser OPO/OPA system, the 355 nm pump laser for OPO provided a maximum pulse energy of 4.2 mJ with pulse duration of about 12.2 ns. The beam diameter was 0.9 mm, the maximum peak power density of the pump pulse reached to 108.2 MW/cm 2 , less than the damage threshold of BBO crystal. The seed power injected into the OPO cavity was about 4.5 mW. When 4.2 mJ pump pulse energy was applied to OPO crystals at a repetition rate of 200 Hz, 0.7 mJ of signal pulse energy at 486.1 nm was detected, corresponding to OPO signal conversion efficiency of 16.6%. The pulse duration of the signal pulse was 10.8 ns, and the linewidth was about 66 MHz. The near-field spot size of the OPO signal laser beam was around 1.5 mm. Then, this signal beam was coupled into the OPA crystals after a beam expander, and the spot diameter at the end-face of the OPA crystal was extended to 4.2 mm. The beam waist size of 355 nm pump laser inside OPA crystal was about 4.1 mm. The maximum pulse energy of 355 nm laser for OPA was 60.3 mJ with pulse width of 6 ns, corresponding to 152.2 MW/cm 2 peak power density. The variation of amplified 486.1 nm signal pulse energy from this BBO-OPA as a function of the applied pump pulse energy was detected and displayed in Fig. 3 . It could be found that, with the increase of pump pulse energy, the amplified blue signal pulse energy also gradually increased firstly, then the growth trend became more rapidly when the pump energy was increased more than 20 mJ, and no saturation was observed under the maximum pump energy applied. The maximum 486.1 nm signal pulse energy of 22.0 mJ was obtained with 60.3 mJ pump pulse energy input, corresponding to an energy extraction efficiency of 35.4%. The temporal profile of the OPO signal pulse, OPA pump pulse and amplified signal pulse at 486.1 nm was detected by a Thorlabs Si Biased Detector (DET025AL/M) and recorded by a Tektronix Oscilloscope (MDO34), as shown in Fig. 4 . Around 5.9 ns pulse duration of the amplified signal laser at 486.1 nm was obtained, which was basically consistent with the 355 nm pump pulse duration, and was much narrower than the initial OPO signal pulse duration. The blue signal laser beam quality factor (M 2 ) was detected by Spiricon silicon CCD camera (SP620), and the result was shown in Fig. 5 , the fitting curves revealed that the beam M 2 factor in x and y direction was 2.29 and 2.17, respectively. The beam intensity distribution of amplified 486.1 nm signal laser with the maximum pulse energy output was also detected, as shown the insert of Fig. 5 . The near-field beam intensity profile of blue signal laser was nearly circular with the beam diameter of 3.2 mm, corresponding to far-field beam divergence of θx = 1.16 mrad and θy = 1.05 mrad. Thus, more than 46.4 MW/cm 2 peak power density at 486.1 nm could be launched from this BBO-OPA system. Since the x direction was the walk-off orientation between the pump laser (extraordinary light) and the signal laser (ordinary light) inside the BBO crystals, the arrangement of two BBO crystals cascaded in cross symmetry could effectively compensates the walk-off effect between pump beam and signal beam in BBO crystals, so that the signal laser beam had a high beam quality in both x and y directions. The central wavelength and spectrum linewidth of the amplified blue signal laser pulse with or without single-frequency seeder injection were measured in experiments by a HighFinesse Wavelength Meter Angstrom (WS/6L), and the results were shown in Fig. 6 . When no seed laser was injected into OPO cavity, the spectral linewidth of the amplified 486.1 nm blue signal laser was too wide for the wavelength meter to get an accurate value, see Fig. 6 (a). On the other hand, when the seed laser was injected into OPO cavity, the spectral linewidth of the amplified 486.1 nm blue signal laser was less than 400 fm, reached the measurement resolution limitation of the Wavelength Meter. The central wavelength of the amplified blue signal laser was at 486.134 nm, see Fig. 6 (b), which was well matched the H-β Fraunhofer line of solar spectrum. In order to obtain the actually value of the spectral linewidth of amplified pulse, the optical heterodyne method was employed. The 486.1 nm single frequency seed laser with 100 kHz linewidth was used as the reference signal, and the heterodyne beat spectrum was detected by a Thorlabs Si Biased Detector (DET025AL/M), finally recorded by a Tektronix Oscilloscope (MDO34), as shown in Fig. 7 (a). Its Fast-Fourier-Transform (FFT) result was shown in Fig. 7 (b), and about 120 MHz of the spectral linewidth (full width at half maximum) was achieved. 4. Conclusion In summary, a single longitudinal mode, high peak-power 486.1 nm wavelength pulse laser based on seed injection OPO/OPA system was proposed. At a pulse repetition rate of 200 Hz, with the maximum pump pulse energy of 60.3 mJ at 355 nm wavelength, the signal laser pulse at 486.1 nm was amplified to 22.0 mJ, corresponding to an extraction efficiency of 35.4%. The amplified 486.1 nm signal pulse had a pulse width of about 5.9 ns with peak power density of 46.4 MW/cm 2 , and the beam quality factor of M 2 was less than 2.3. The central wavelength was well matched solar H-β Fraunhofer line at 486.134 nm, and its spectral linewidth of 120 MHz (94.5 fm) was much narrower than the bandwidth of H-β Fraunhofer line. Larger signal pulse energy could be obtained with the increasing of pump pulse energy or increasing the stages of BBO-OPA. This kind of SLM high-peak power nanosecond pulsed laser in blue has a very great application prospect for the ocean lidar, especially for the high spectral resolution oceanic lidar transmitter light source, and considerable high SNR could be achieved. Declarations Author Contribution Q. L. : executed the experiment and wrote the manuscript. J.M. : designed the technical route of the laser and revised the manuscript. Z. H. :assisted in the experiment. J. Z. : gave scientific discussion and suggestions. T. L., H. M. and W. C. provided guidance. X. Z. : provided guidance, revised and edited the manuscript. All authors reviewed the manuscript. Acknowledgements This work is supported by the National Key R&D Program of China (Grant No. 2022YFB3901700) and the Innovation Foundation of Chinese Academy of Sciences (Grant No. CXJJ-22S005). References S. Q. 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Cite Share Download PDF Status: Published Journal Publication published 14 Mar, 2025 Read the published version in Applied Physics B → Version 1 posted Editorial decision: Revision requested 24 Feb, 2025 Reviews received at journal 11 Feb, 2025 Reviews received at journal 10 Feb, 2025 Reviews received at journal 04 Feb, 2025 Reviewers agreed at journal 02 Feb, 2025 Reviewers agreed at journal 31 Jan, 2025 Reviewers agreed at journal 30 Jan, 2025 Reviewers invited by journal 24 Jan, 2025 Editor assigned by journal 17 Jan, 2025 Submission checks completed at journal 14 Jan, 2025 First submitted to journal 14 Jan, 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-5826037","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":402020013,"identity":"d4d41481-9e44-40e1-9a26-83485a2a54ac","order_by":0,"name":"Qihui Luo","email":"","orcid":"","institution":"University of Chinese Academy of Sciences","correspondingAuthor":false,"prefix":"","firstName":"Qihui","middleName":"","lastName":"Luo","suffix":""},{"id":402020014,"identity":"c441505b-5cb4-4175-8da9-1e712891fbb0","order_by":1,"name":"Jian 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1","display":"","copyAsset":false,"role":"figure","size":2017164,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic diagram of the experimental setup\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/13eddbd657d6e65e52c12145.png"},{"id":73981549,"identity":"98c34c06-f726-403a-b2bd-a5cd286fc769","added_by":"auto","created_at":"2025-01-16 15:12:57","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":681921,"visible":true,"origin":"","legend":"\u003cp\u003eSimulation curve of amplified signal pulse energy transformation with crystal length\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/9c49183cd4c32403131541b9.png"},{"id":73981557,"identity":"f3383621-0435-4293-b69f-7a8b175a34b3","added_by":"auto","created_at":"2025-01-16 15:12:57","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":775724,"visible":true,"origin":"","legend":"\u003cp\u003eAmplified signal pulse energy as a function of the pump pulse energy\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/e3c229b7cf7bdbeb4ebea468.png"},{"id":73981558,"identity":"c87851cd-af28-48ca-8bc4-efd2677e1a0d","added_by":"auto","created_at":"2025-01-16 15:12:57","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1451987,"visible":true,"origin":"","legend":"\u003cp\u003ePulse temporal profile of the OPO signal laser, OPA pump laser and amplified signal laser at 486.1 nm\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/dedcde18e2becb7cebb9f75e.png"},{"id":73981552,"identity":"c3e974c7-cd95-497b-b90d-55cff65799f7","added_by":"auto","created_at":"2025-01-16 15:12:57","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":2155601,"visible":true,"origin":"","legend":"\u003cp\u003eThe beam diameter (Dx and Dy) measured at varying distance and near-field beam profile of amplified signal laser at 486.1 nm\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/5ced625eb8b5aa729515ce10.png"},{"id":73981566,"identity":"af23f1df-c676-4e7c-8a41-5479b92918c6","added_by":"auto","created_at":"2025-01-16 15:12:58","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":8238142,"visible":true,"origin":"","legend":"\u003cp\u003eSpectral central wavelength and linewidth measurement of the amplified 486.1 nm signal laser. (a). without seed injection (b). seed injection\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/640c2fb869f54531c24bbae1.png"},{"id":73981572,"identity":"d478f95d-88dc-43d2-b814-d3232b4c1bc8","added_by":"auto","created_at":"2025-01-16 15:12:58","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1753821,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Heterodyne beat spectrum of amplified signal pulse. (b) FFT result derived from beat signal.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/9ee6a5d52382850a456d3940.png"},{"id":78688990,"identity":"43efedf2-00bf-484b-8e46-13017093bf3b","added_by":"auto","created_at":"2025-03-17 16:09:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":21701851,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5826037/v1/5f92f4e9-eb0f-46c7-89ee-c2b2d08f2b2f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eSingle longitudinal mode 486.1 nm wavelength laser generation from β-Ba\u003csub\u003e2\u003c/sub\u003eBO\u003csub\u003e4\u003c/sub\u003e -optical parametric amplifier system for ocean detection\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eBlue-green wave band is known as the optical transmission window of ocean water because its attenuation coefficient in water is significantly lower than other wave bands \u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e, so that the all-solid-state blue-green laser has been widely used in ocean detection lidar, underwater wireless optical communication, laser mapping system and so on \u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e. For clear pelagic water, blue laser emitting within 420 nm-490 nm is considered the optimal source for ocean detection lidar. In 2019, Liu et al. \u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e demonstrated that 486.1 nm was the optimal transmitter wavelength for spaceborne ocean lidar. Since solar spectrum contains a H-β Fraunhofer line at 486.134 nm (0.14 nm bandwidth), it is believed that utilizing this H-β Fraunhofer line as the working wavelength can significantly improve the signal-to-noise ratio (SNR) for marine detection, so that this kind of ocean lidar and underwater wireless optical communication systems can work effectively in daytime with sunlight background \u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe primarily methods for obtaining blue laser output involve Pr\u003csup\u003e3+\u003c/sup\u003e doped crystal laser \u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e, Raman frequency shift technique \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e and nonlinear frequency conversion \u003csup\u003e[\u003cspan additionalcitationids=\"CR13 CR14\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. The blue laser source based on nonlinear frequency conversion can obtain higher peak power than the other two methods, which is more suitable for ocean lidar application. Till now, an optical parametric oscillator (OPO) pumped by 355 nm ultraviolet laser is an effective way to obtain blue laser output, which has advantages of high repetition rate, high output peak power, high beam quality and wavelength tunable, these characteristics make it an excellent laser source for ocean lidar.\u003csup\u003e[\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e In 2018, Rao et al. \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e achieved tunable signal output within 490 nm to 630 nm at 5 kHz repetition rate from a type-I phase matching β-Ba\u003csub\u003e2\u003c/sub\u003eBO\u003csub\u003e4\u003c/sub\u003e (BBO)-OPO system, the maximum output power was 3.23 W, and spectral linewidth increased from 0.2 nm to 0.5 nm with signal wavelength increasing. From a type-II BBO-OPO system, continuous tunable output from 490 nm to 590 nm with linewidth of 0.15 nm was achieved at a repetition rate of 2 kHz. In 2021, by inserting a Fabry-Perot etalon (F-P) in the OPO cavity, they achieved tunable single longitudinal mode (SLM) laser output in the range of 500 nm to 600 nm, the optical conversion efficiency was around 4.1% with 62 mW output power, and the average spectral linewidth was less than 250 MHz \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e. Recent years, research works on lasers emitting at the dark line of solar spectrum have been boosted, in 2018, Ma et al. \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e demonstrated a 486.1 nm blue laser output with a maximum pulse energy of 62 mJ from a BBO-OPO unit, the spectrum linewidth was less than 0.1 nm, and the peak output power was up to 7.7 MW. In 2020, a compact BBO-OPO system with 9.6 mJ blue pulse energy output at 100 Hz repetition rate was successfully equipped in a home-made airborne ocean detection lidar, but its spectral linewidth reached to about 0.3 nm \u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. Although up to 162 mJ blue pulse energy could be obtained from a BBO-OPO system, the spectral linewidth was typically more than 0.34 nm \u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e, which was wider than the linewidth of solar H-β line. It can be found that a major limitation of those studies is that fails to maintain narrow-linewidth characteristics with high pulse energy output simultaneously. This makes it limited in applications, such as ocean lidar with high spectral resolution requirements. With the rapid developing of ocean remote sensing technology, the requirements for blue laser as the transmitter source are constantly improving. It has become a key problem to be solved urgently for obtaining blue pulse laser with high energy and high peak power with reasonable narrow spectral linewidth.\u003c/p\u003e \u003cp\u003eInjection seeded OPO has been proven an effectively method to narrow OPO signal light linewidth, but the effect of seed injection will become worse in the case of high energy pumping. Therefore, it is difficult to realize high energy pulse output with narrow-linewidth just basing OPO. There have been some previous works obtained high-energy infrared laser output from an OPO/OPA hybrid structure \u003csup\u003e[\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. Even more, when an injection seeded OPO with narrow-linewidth was used as the signal for OPA, and finally higher energy pulse with narrow-linewidth could be achieved \u003csup\u003e[\u003cspan additionalcitationids=\"CR24\" citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. However, to the best of our knowledge, blue SLM signal wave amplified by this kind of OPO/OPA system has not been reported yet.\u003c/p\u003e \u003cp\u003eIn this paper, we demonstrated a SLM 486.1 nm blue pulse laser based on a single-frequency seed injection OPO/OPA system. Pumped by a home-made 355 nm SLM pulse laser at a repetition rate of 200 Hz, output 486.1 nm pulse energy of 22.0 mJ was obtained with the maximum pump pulse energy of 60.3 mJ, corresponding to an extraction efficiency of 35.4%. The peak power density of output blue laser pulse was 46.4 MW/cm\u003csup\u003e2\u003c/sup\u003e, and the beam quality factor of M\u003csup\u003e2\u003c/sup\u003e was less than 2.3. The central wavelength was 486.134 nm with spectral linewidth of 120 MHz. This SLM and high-peak power blue pulsed laser has the potential of improving the detection performance of ocean lidar and realizing high spectral resolution detection.\u003c/p\u003e"},{"header":"2. Experimental Setup","content":"\u003cp\u003eThe schematic diagram of the SLM 486.1 nm blue pulsed laser was shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. The 1064 nm SLM fiber laser consisted of a continuous wave output non-planar ring oscillator (NPRO) seed laser, an acousto-optic modulator (AOM) acted as chopper, and two stages of fiber amplifiers. The pulse output from this 1064 nm SLM fiber laser was split two by a 1\u0026times;2 Polarization Maintaining Tap Isolator (PMTI), and then coupled into the OPO and OPA fiber amplifiers respectively. The 355 nm laser for OPO was composed of one stage Nd:YAG rod amplifier and a tripling frequency module. The 355 nm laser for OPA was composed of a three-stage Nd:YAG rod amplifier and a tripling frequency module. The maximum 355 nm pump pulse energy for OPA was around 60.3 mJ, and that for OPO was about 4.2 mJ. The 486.1 nm seed was a SLM continuous wave laser obtained from a 972.2 nm distributed feedback laser (DFB) by a PPLN frequency doubling module.\u003c/p\u003e \u003cp\u003eThe 486.1 nm seed laser and 355 nm pump laser passed through the beam combiner M1, then entered the four-mirror ring cavity of OPO, which was a plane-plane resonator with total cavity length of 230 mm. The input mirror was also act as the output coupling mirror (OC), which was anti-reflection (AR) coated at 355 nm and 1313 nm, and partly reflection coated at 486 nm with transmission of 30%. The mirror M2 was also anti-reflection (AR) coated at 355 nm and 1313 nm, and high-reflection (HR) coated at 486 nm. And the other two cavity mirrors were high-reflection (HR) coated at 486 nm. In this OPO cavity, two 5 mm \u0026times; 5 mm \u0026times; 10 mm type-I phase matching BBO crystals, cut at θ\u0026thinsp;=\u0026thinsp;29.6\u0026deg;, ϕ\u0026thinsp;=\u0026thinsp;90\u0026deg;, were inserted between the OC and M2 as parametric medium. Similar to our previous work \u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e, these two BBO crystals were placed symmetrically with respect to the pump beam axis to compensate the walk-off effect.\u003c/p\u003e \u003cp\u003eThe 486.1 nm signal laser beam from OPO was coupled into the OPA unit after passing through a beam expander with the power loss of 6%. The beam expander was designed to make the beam waist of the signal laser match the 355 nm pump beam waist inside the BBO crystals of OPA, which was helpful to improve the conversion efficiency of OPA. In experiment, the 355 nm pump lasers for OPA and OPO were homologous in time, but, due to the existence of signal pulse establishing time inside OPO, the signal output from OPO had a certain delay relative to the pump pulse, this extra delay should be offset by connecting a suitable length of fiber for the OPA fiber amplifier, shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e was the simulated curve of the amplified signal pulse energy as the function of the crystal length by the SNLO software, it revealed that the amplified signal pulse energy from OPA increased firstly and then decreased with the increase of crystal length due to the reverse transcription process occured. The maximum value of amplified pulse energy in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e occurred at the OPA crystal length of about 30 mm. Therefore, in this experiment, the total length of the parameter crystals was designated according to this simulation result.\u003c/p\u003e \u003cp\u003eThe OPO signal laser beam and the 355 nm pump laser beam for OPA were coupled into BBO crystals by M3. Thess two BBO crystals were both 15 mm in length with cross-section of 10 mm \u0026times; 10 mm, cut at θ\u0026thinsp;=\u0026thinsp;29.6\u0026deg;, ϕ\u0026thinsp;=\u0026thinsp;90\u0026deg; (type-I phase matching) and set symmetrically with respect to the pump laser beam axis to compensate the walk-off effect.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003eIn this blue pulsed laser OPO/OPA system, the 355 nm pump laser for OPO provided a maximum pulse energy of 4.2 mJ with pulse duration of about 12.2 ns. The beam diameter was 0.9 mm, the maximum peak power density of the pump pulse reached to 108.2 MW/cm\u003csup\u003e2\u003c/sup\u003e, less than the damage threshold of BBO crystal. The seed power injected into the OPO cavity was about 4.5 mW. When 4.2 mJ pump pulse energy was applied to OPO crystals at a repetition rate of 200 Hz, 0.7 mJ of signal pulse energy at 486.1 nm was detected, corresponding to OPO signal conversion efficiency of 16.6%. The pulse duration of the signal pulse was 10.8 ns, and the linewidth was about 66 MHz. The near-field spot size of the OPO signal laser beam was around 1.5 mm. Then, this signal beam was coupled into the OPA crystals after a beam expander, and the spot diameter at the end-face of the OPA crystal was extended to 4.2 mm. The beam waist size of 355 nm pump laser inside OPA crystal was about 4.1 mm. The maximum pulse energy of 355 nm laser for OPA was 60.3 mJ with pulse width of 6 ns, corresponding to 152.2 MW/cm\u003csup\u003e2\u003c/sup\u003e peak power density.\u003c/p\u003e \u003cp\u003eThe variation of amplified 486.1 nm signal pulse energy from this BBO-OPA as a function of the applied pump pulse energy was detected and displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. It could be found that, with the increase of pump pulse energy, the amplified blue signal pulse energy also gradually increased firstly, then the growth trend became more rapidly when the pump energy was increased more than 20 mJ, and no saturation was observed under the maximum pump energy applied. The maximum 486.1 nm signal pulse energy of 22.0 mJ was obtained with 60.3 mJ pump pulse energy input, corresponding to an energy extraction efficiency of 35.4%.\u003c/p\u003e \u003cp\u003eThe temporal profile of the OPO signal pulse, OPA pump pulse and amplified signal pulse at 486.1 nm was detected by a Thorlabs Si Biased Detector (DET025AL/M) and recorded by a Tektronix Oscilloscope (MDO34), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Around 5.9 ns pulse duration of the amplified signal laser at 486.1 nm was obtained, which was basically consistent with the 355 nm pump pulse duration, and was much narrower than the initial OPO signal pulse duration.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe blue signal laser beam quality factor (M\u003csup\u003e2\u003c/sup\u003e) was detected by Spiricon silicon CCD camera (SP620), and the result was shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, the fitting curves revealed that the beam M\u003csup\u003e2\u003c/sup\u003e factor in x and y direction was 2.29 and 2.17, respectively. The beam intensity distribution of amplified 486.1 nm signal laser with the maximum pulse energy output was also detected, as shown the insert of Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The near-field beam intensity profile of blue signal laser was nearly circular with the beam diameter of 3.2 mm, corresponding to far-field beam divergence of θx\u0026thinsp;=\u0026thinsp;1.16 mrad and θy\u0026thinsp;=\u0026thinsp;1.05 mrad. Thus, more than 46.4 MW/cm\u003csup\u003e2\u003c/sup\u003e peak power density at 486.1 nm could be launched from this BBO-OPA system. Since the x direction was the walk-off orientation between the pump laser (extraordinary light) and the signal laser (ordinary light) inside the BBO crystals, the arrangement of two BBO crystals cascaded in cross symmetry could effectively compensates the walk-off effect between pump beam and signal beam in BBO crystals, so that the signal laser beam had a high beam quality in both x and y directions.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe central wavelength and spectrum linewidth of the amplified blue signal laser pulse with or without single-frequency seeder injection were measured in experiments by a HighFinesse Wavelength Meter Angstrom (WS/6L), and the results were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. When no seed laser was injected into OPO cavity, the spectral linewidth of the amplified 486.1 nm blue signal laser was too wide for the wavelength meter to get an accurate value, see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (a). On the other hand, when the seed laser was injected into OPO cavity, the spectral linewidth of the amplified 486.1 nm blue signal laser was less than 400 fm, reached the measurement resolution limitation of the Wavelength Meter. The central wavelength of the amplified blue signal laser was at 486.134 nm, see Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e (b), which was well matched the H-β Fraunhofer line of solar spectrum.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIn order to obtain the actually value of the spectral linewidth of amplified pulse, the optical heterodyne method was employed. The 486.1 nm single frequency seed laser with 100 kHz linewidth was used as the reference signal, and the heterodyne beat spectrum was detected by a Thorlabs Si Biased Detector (DET025AL/M), finally recorded by a Tektronix Oscilloscope (MDO34), as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e(a). Its Fast-Fourier-Transform (FFT) result was shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e (b), and about 120 MHz of the spectral linewidth (full width at half maximum) was achieved.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eIn summary, a single longitudinal mode, high peak-power 486.1 nm wavelength pulse laser based on seed injection OPO/OPA system was proposed. At a pulse repetition rate of 200 Hz, with the maximum pump pulse energy of 60.3 mJ at 355 nm wavelength, the signal laser pulse at 486.1 nm was amplified to 22.0 mJ, corresponding to an extraction efficiency of 35.4%. The amplified 486.1 nm signal pulse had a pulse width of about 5.9 ns with peak power density of 46.4 MW/cm\u003csup\u003e2\u003c/sup\u003e, and the beam quality factor of M\u003csup\u003e2\u003c/sup\u003e was less than 2.3. The central wavelength was well matched solar H-β Fraunhofer line at 486.134 nm, and its spectral linewidth of 120 MHz (94.5 fm) was much narrower than the bandwidth of H-β Fraunhofer line. Larger signal pulse energy could be obtained with the increasing of pump pulse energy or increasing the stages of BBO-OPA. This kind of SLM high-peak power nanosecond pulsed laser in blue has a very great application prospect for the ocean lidar, especially for the high spectral resolution oceanic lidar transmitter light source, and considerable high SNR could be achieved.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eQ. L. : executed the experiment and wrote the manuscript. J.M. : designed the technical route of the laser and revised the manuscript. Z. H. :assisted in the experiment. J. Z. : gave scientific discussion and suggestions. T. L., H. M. and W. C. provided guidance. X. Z. : provided guidance, revised and edited the manuscript. All authors reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eThis work is supported by the National Key R\u0026amp;D Program of China (Grant No. 2022YFB3901700) and the Innovation Foundation of Chinese Academy of Sciences (Grant No. CXJJ-22S005).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eS. Q. Duntley, \u0026ldquo;Light in the Sea,\u0026rdquo; J. Opt. Soc. Am. \u003cstrong\u003e53\u003c/strong\u003e, 214 (1963). \u003c/li\u003e\n\u003cli\u003eS. A. Sullivan, \u0026ldquo;Experimental Study of the Absorption in Distilled Water, Artificial Sea Water, and Heavy Water in the Visible Region of the Spectrum,\u0026rdquo; J. Opt. Soc. Am. \u003cstrong\u003e53\u003c/strong\u003e, 962 (1963).\u003c/li\u003e\n\u003cli\u003eH. Liu, P. Chen, Z.H. Mao, D. L. Pan, and Y. He, \u0026ldquo;Subsurface plankton layers observed from airborne lidar in Sanya Bay, South China Sea,\u0026rdquo; Opt. 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Lett. \u003cstrong\u003e12\u003c/strong\u003e, 091401 (2014).\u003c/li\u003e\n\u003cli\u003eQ. H. Luo, J. Ma, M. Wang, T. T. Lu, and X. L. Zhu, \u0026ldquo;All-solid-state far-UVC pulse laser at 222 nm wavelength for UVC disinfection,\u0026rdquo; Chin. Opt. Lett. \u003cstrong\u003e21\u003c/strong\u003e, 011401 (2023).\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":"blue laser, optical parametric amplifier, optical parametric oscillator, single longitudinal mode","lastPublishedDoi":"10.21203/rs.3.rs-5826037/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5826037/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA single longitudinal mode (SLM) 486.1 nm blue pulsed laser was investigated by adopting a single-frequency distributed feedback laser (DFB) injected optical parametric oscillator (OPO) and optical parametric amplifier (OPA) structure, pumped by a 355 nm ultraviolet SLM laser at pulse repetition rate of 200 Hz. The maximum output pulse energy of 22.0 mJ was obtained from this injection seeded OPO/OPA system, corresponding to energy extraction efficiency of 35.4% and peak power density of 46.4 MW/cm\u003csup\u003e2\u003c/sup\u003e. The central wavelength of output laser pulse was 486.134 nm, which was well matched the H-β Fraunhofer line of solar spectrum, and the detected spectral linewidth was around 120 MHz.\u003c/p\u003e","manuscriptTitle":"Single longitudinal mode 486.1 nm wavelength laser generation from β-Ba2BO4 -optical parametric amplifier system for ocean detection","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-16 15:12:52","doi":"10.21203/rs.3.rs-5826037/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-02-24T12:54:58+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-11T05:50:15+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-10T23:29:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-02-04T13:27:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"125768061025979579640835083627818926726","date":"2025-02-02T14:42:28+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"263411174796716303416680090829133921700","date":"2025-02-01T00:34:47+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"118427357975529243707090559568524427631","date":"2025-01-30T10:11:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-01-25T02:08:59+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-17T14:01:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-14T12:55:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"Applied Physics B","date":"2025-01-14T09:47:48+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":"4c008978-877c-4088-b674-0731f1698b92","owner":[],"postedDate":"January 16th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-03-17T16:01:58+00:00","versionOfRecord":{"articleIdentity":"rs-5826037","link":"https://doi.org/10.1007/s00340-025-08449-4","journal":{"identity":"applied-physics-b","isVorOnly":false,"title":"Applied Physics B"},"publishedOn":"2025-03-14 15:57:44","publishedOnDateReadable":"March 14th, 2025"},"versionCreatedAt":"2025-01-16 15:12:52","video":"","vorDoi":"10.1007/s00340-025-08449-4","vorDoiUrl":"https://doi.org/10.1007/s00340-025-08449-4","workflowStages":[]},"version":"v1","identity":"rs-5826037","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5826037","identity":"rs-5826037","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}