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SBS pulse compression using bulk fused silica by diode-pumped solid-state lasers at 1??kHz repetition rate
摘要： This study is focused on constructing a highly stable diode-pumped solid-state laser system by conducting experiments on high-repetition-rate SBS pulse compression using bulk fused silica. A multi-rod serial-connection structure is adopted for SBS expriments by comparing K8 glass and fused silica medium at a 10 Hz repetition rate. The optimized structure is obtained according to variation of the pump power density. Based on the optimized structure, fused silica-based SBS pulse compression is carried out in the range of 100–1000 Hz and the parameter performance of laser system after compression is also evaluated by comparing a HT270 liquid medium. Experimental results indicate that the energy e?ciency of fused silica-based SBS is improved by approximately 40% compared with that of K8 glass. Further, the energy relative standard deviation of fused silica-based SBS is reduced by approximately 88% compared with HT270 medium, indicating that bulk fused silica is advantageous for high-repetition-rate SBS pulse compression because of its un-?uidity, high thermal conductivity and power-load ability. In addition, a 1 kHz highly-stable sub-nanosecond compressed pulse is achieved using bulk fused silica medium at a pump energy of 50 mJ. Furthermore, the SBS energy e?ciency can be further improved by increasing the input energy.
关键词： Pulse compression,High repetition rate,Solid-state lasers,Sub-nanosecond pulse,Stimulated Brillouin scattering (SBS)
更新于2025-09-23 15:21:01
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Femtosecond laser irradiation of titanium oxide thin films: accumulation effect under IR beam
摘要： This paper discusses the mechanisms of laser-induced periodic surface structures (LIPSS) formation using a high repetition rate femtosecond laser beam irradiation of magnetron-sputtered titanium oxide thin films (TiO1.8) grown onto SiO2/Si substrates. An Yb:YKW 500 fs linearly polarized laser emitting at a wavelength, λ, of 1030 nm, was used to irradiate the films (300 nm thickness) at a repetition rate of 100 kHz under both static and dynamic (scanning) conditions. Under static beam conditions, an incubation behavior related to materials in thin film form was established with a damage threshold of 72 mJ/cm2. Close to this fluence value and increasing the number of laser shots from 1 to 1000, micro-cracking occurred and propagated inside the beam waist diameter zone estimated close to 60 μm. In addition, using a higher fluence value of 280 mJ/cm2, i.e., well above the damage threshold, a melting occurred in an intermediate zone within the irradiated area, with a surprising ‘cure effect’ that contributes to the micro-cracks stabilization. Simultaneously, at the center of the Gaussian laser beam spot, the entire film ablation was observed. Furthermore, irradiation under dynamic mode with a scanning speed of 4 mm/s and a repetition rate of 100 kHz were achieved for the large-scale processing of the TiO1.8 films up to surface area of 25 × 25 mm2. For these irradiation conditions case that correspond to a fluence of 110 mJ/cm2 and a cumulative number of shots of 3000, 2D-LIPSS nano-cracks (200 nm length and λ/8 to λ/9 period) are obtained over the whole irradiated surface, a phenomenon that is mainly attributed to a thermo-mechanical ablation mechanism.
关键词： Femtosecond laser beam,Titanium oxide film,Micro/nano-cracks,High repetition rate,Incubation,LIPSS
更新于2025-09-23 15:21:01
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High repetition rate and high power picosecond terahertz parametric amplifier with a KTiOPO <sub/>4</sub> crystal
摘要： A high repetition rate, high power, and widely tunable THz parametric amplifier (TPA) with a KTiOPO4 crystal has been demonstrated in this work. A peak power of 1.7 kW and an average power of 89 lW have been obtained at a frequency of 5.74 THz and a repetition rate of 10 kHz. The radiation is expected to be Fourier transform limited, with a pulse duration (full width at half maximum, FWHM) of 5.4 ps and a bandwidth (FWHM) of 81 GHz, and has an M2 parameter close to the pump laser. We have also tested the TPA at a repetition rate of 100 kHz, and the results indicate that mW-level (average power) THz radiation output is feasible with a stronger pump laser that is commercially available.
关键词： high power,terahertz parametric amplifier,KTiOPO4 crystal,picosecond,high repetition rate
更新于2025-09-23 15:19:57
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High Repetition Rate Mid-Infrared Differential Absorption Lidar for Atmospheric Pollution Detection
摘要： Developments in mid-infrared Di?erential Absorption Lidar (DIAL), for gas remote sensing, have received a signi?cant amount of research in recent years. In this paper, a high repetition rate tunable mid-infrared DIAL, mounted on a mobile platform, has been built for long range remote detection of gas plumes. The lidar uses a solid-state tunable optical parametric oscillator laser, which can emit laser pulse with repetition rate of 500 Hz and between the band from 2.5 μm to 4 μm. A monitoring channel has been used to record the laser energy in real-time and correct signals. Convolution correction technology has also been incorporated to choose the laser wavelengths. Taking NO2 and SO2 as examples, lidar system calibration experiment and open ?eld observation experiment have been carried out. The observation results show that the minimum detection sensitivity of NO2 and SO2 can reach 0.07 mg/m3, and 0.31 mg/m3, respectively. The e?ective temporal resolution can reach second level for the high repetition rate of the laser, which demonstrates that the system can be used for the real-time remote sensing of atmospheric pollution gas.
关键词： convolution correction,high repetition rate,di?erential absorption lidar,mid-infrared
更新于2025-09-23 15:19:57
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Exploring phase contrast imaging with a laser-based K?± x-ray source up to relativistic laser intensity
摘要： this study explores the ability of a hard Kα x-ray source (17.48 keV) produced by a 10 TW class laser system operated at high temporal contrast ratio and high repetition rate for phase contrast imaging. For demonstration, a parametric study based on a known object (PET films) shows clear evidence of feasibility of phase contrast imaging over a large range of laser intensity on target (from ~1017 W/cm2 to 7.0 × 1018 W/cm2). To highlight this result, a comparison of raw phase contrast and retrieved phase images of a biological object (a wasp) is done at different laser intensities below the relativistic intensity regime and up to 1.3 × 1019 W/cm2. this brings out attractive imaging strategies by selecting suitable laser intensity for optimizing either high spatial resolution and high quality of image or short acquisition time.
关键词： biological imaging,laser intensity,phase contrast imaging,high repetition rate,Kα x-ray source
更新于2025-09-23 15:19:57
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Laser-diode dual-end-pumped electro-optic Q-switched slab Tm:YAP laser
摘要： A high-repetition-rate and double-end pumped electro-optic Q-switched Tm:YAlO3 (Tm:YAP) laser is reported. The Tm:YAP slab crystal cut by c-axis is used as the laser gain medium, and the RbTiOPO4(RTP) crystal is selected as the electro-optic Q-switched crystal. Choosing volume Bragg gratings (VBG) as the input mirror to narrow the output line width. When the pump power is 79.2 W, at a repetition rate of 10 kHz, maximum average-output-power of 21.96 W is achieved, with the pulse width of 20.64 ns and output energy of 2.20 mJ. The output peak power is 107.3 kW and the slope efficiency is 29.2%. The center wavelength is 1937.87 nm and the line width is 0.73 nm. The beam quality in the x direction is 1.48, and in the y direction is 1.50.
关键词： Electro-optic Q-switch,High repetition rate,Tm:YAP laser,RTP
更新于2025-09-23 15:19:57
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High-repetition-rate laser-induced damage of indium tin oxide films and polyimide films at a 1064 nm wavelength
摘要： Experiments and thermal modeling of indium tin oxide transparent conductive thin film and polyimide alignment thin film coated on fused silica substrates damaged with a 1064 nm high-repetition-rate laser are described. High-repetition-rate laser irradiation results in damaged morphologies of the bulge at low laser power density and formation of a pit in the center of the bulge at higher laser power density. The damage process that is consistent with the observations as a function of laser power density and irradiation time is related to thermal effect. Simulation of the temperature-rise by exposure to high-repetition-rate laser describes the thermal effect with different pulse oscillation.
关键词： high-repetition-rate laser,polyimide,laser-induced damage,thermal modeling,indium tin oxide
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - CPA-Free High Repetition Rate Few-Cycle OPCPA
摘要： Optical Parametric Chirped-Pulse Amplification (OPCPA) systems have become a key-enabling light source providing high energies at high repetition rates and covering a wide range of wavelengths from the visible to the mid-infrared with few cycle pulse durations. However, most systems are complex and rather bulky due to large fiber or regenerative amplifiers used as a pump source. The additional need for a stretcher and compressor in the pump laser adds complexity, timing jitter and reduces the overall optical-to-optical efficiency. In this work, we present a novel approach that allows a high repetition rate, few-cycle OPCPA system based on a compact and CPA-free solid-state amplifier system. We recently demonstrated the feasibility of the concept using two subsequent direct diode pumped solid-state amplifier modules (neoVAN-2P, neoLASE GmbH) based on Nd:YVO4 as a pump laser. We were able to amplify the ultrabroadband pulses from a home-built, octave-spanning Ti:sapphire laser to generate few-cycle pulses with a duration of 8.7 fs with an energy of 18 μJ at 10 kHz repetition rate. The compact, CPA-free system has a reduced system footprint and high efficiency as no losses in a compressor are occurring. For the amplification of few-cycle signal pulses, stretching to more than a few ps and subsequent recompression is problematic and limited the achievable pulse duration in our previous system. Insufficient temporal overlap between pump and signal pulses in the OPA stages will however cause lower parametric conversion efficiency and a significantly higher super-fluorescence background. In this work, we show for the first time a compact few-cycle OPCPA system using a newly developed Yb:YAG solid-state amplifier as pump source. The Yb:YAG amplifier modules are capable of generating pump pulses with a duration of < 600 fs. These output parameters are ideally suited for few-cycle OPCPA pumping and eliminate the above mentioned drawbacks of the previous approach. The high pump power and short pulse duration delivered by the amplifier modules enable a similar performance of the OPCPA as typical high repetition rate, rod-fiber based systems at the benefit of CPA-free operation and compactness. As the amplifier modules are equipped with an efficient CPA-free, directly diode pumped solid-state pump source with all-optical synchronization to an ultra-broadband Ti:sapphire seed oscillator. The availability of such portable, breadboard-user-friendly OPCPA will be a great benefit for many applications as spectroscopy, nonlinear imaging or even attosecond physics.
关键词： Yb:YAG,solid-state amplifier,few-cycle pulses,high repetition rate,OPCPA
更新于2025-09-19 17:13:59
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Calibration-free elemental analysis combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy
摘要： Calibration-free (CF) method combined with high repetition rate laser-ablation spark-induced breakdown spectroscopy (HRR LA-SIBS) was ?rst utilized to realize elemental analysis of alloy samples. A compact ?ber laser operated at 30 kHz pulse repetition rate was used to ablate the sample and the spectra were recorded with a compact ?ber spectrometer in non-gated signal recording mode. Three standard aluminum alloy samples were analyzed to evaluate the performance of this technique. Median ?ltering method was applied to reduce the contribution of the continuum background to the intensity of the atomic lines. The averaged electron density was determined to be (2.36–2.49) × 1017 cm?3 according to the Stark broadening of four ionic lines. 11,800 K averaged plasma temperature was estimated from the Saha-Boltzmann plots. The plasma could be veri?ed to be in a state close to local thermodynamic equilibrium. The analytical error was < 0.5% for the major element and < 35% for minor elements with > 0.1% concentrations. It was demonstrated that CF method combined with HRR LA-SIBS was possible to realize reliable quantitative elemental analysis for aluminum alloy samples.
关键词： Calibration-free,Laser-ablation spark-induced breakdown spectroscopy,Elemental analysis,Aluminum alloy,High repetition rate
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Towards a kW-Class Picosecond Laser at 1 kHz
摘要： Secondary sources development such as X-rays for medical applications demand diode-pumped high-energy, high-power and high repetition rate picosecond lasers leading to a race to the kW milestone. Year after year, the pulse energy increased to few hundreds of millijoules at 1 kHz [1], but all the kW systems are based on the Yb:YAG thin disk technology which until now, to the best of our knowledge, has come short to deliver the full kilowatt level at 1 kHz. On the other side, cryogenically cooled bulk Yb:YAG amplifiers has shown its capabilities to reach 1 J at 500 Hz with 3.8 ps pulses [2]. Since two years, CELIA has launched new technology developments for a new system (HORIZON) aiming to reach 1 J, 1 kHz, 1 ps. We selected Yb:YAG crystal as laser gain medium since its thermal properties and its low quantum defect are suitable for high power laser generation. However, its narrow spectral bandwidth and its high saturation fluence impose large constraints on both the amplifier and compressor architectures. Cutting-edge technologies such as hypercompressor [3], divided pulse amplification [4], thin-disk and liquid-cooled disks are explored to address these limitations.
关键词： thin disk technology,cryogenically cooled bulk Yb:YAG amplifiers,high repetition rate,high-power,divided pulse amplification,hypercompressor,picosecond lasers,Yb:YAG,high-energy
更新于2025-09-12 10:27:22