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High-Repetition-Rate and High-Beam-Quality Laser Pulses with 1.5MW Peak Power Generation from a Two-Stage Nd:YVO <sub/>4</sub> Amplifier <sup>*</sup>
摘要： We develop a two-stage end-pumped Nd:YVO4 amplifier seeded by a passively Q-switched microchip laser. An average output power of 13.5 W with repetition rate up to 7 kHz and pulse duration of ～1.24 ns is obtained, corresponding to a pump extraction efficiency of 16.1% (19.5% for the second stage) and peak power of ～1.5 MW. The beam quality factors at maximum output power are measured to be ?? 2 ?? = 1.56 and ?? 2 ?? = 1.48. We introduce an analytical model to estimate gain and beam quality after amplification. This model focuses on the influence of ratio of seed spot radius to pump spot radius when designing an amplifier. Moreover, our experiments reveal that the re-imaging system in the double-pass configuration can be used to enhance the beam quality.
关键词： peak power,high-beam-quality,Nd:YVO4 amplifier,high-repetition-rate,laser pulses
更新于2025-09-12 10:27:22
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Peak-power-clamping in an all-polarization-maintaining Q-switched mode-locking fiber laser
摘要： We report the peak-power-clamping (PPC) effect in a polarization-maintaining (PM) Q-switched mode locking fiber laser. The laser cavity with a compact and stable all-PM fiber configuration can clearly demonstrate three different output states including normal Q-switching, PPC Q-switching, and PPC Q-switched mode-locking (QML) with the increasing pump power. To the best of our knowledge, it is the first time that PPC effect is successfully obtained and analyzed from the Q-switching to QML. This research extends the theory of PPC in pulsed lasers and reveals the potential to achieve ultra-high pulse energy.
关键词： peak-power-clamping,polarization-maintaining,Q-switched mode locking,fiber laser
更新于2025-09-12 10:27:22
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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) - Coherent Beam Combining by Noncollinear Sum-Frequency Generation
摘要： Despite rapid development of fiber laser technologies, highest pulse peak power achievable from fiber lasers eventually approaches limits which are not easy to overcome. Therefore, there is growing interest in methods, which would allow to combine outputs from multiple pulsed fiber lasers into single diffraction-limited beam, and by this enable further scaling. For this reason, numerous coherent and incoherent beam combining methods are being proposed and investigated. Not so well investigated class of beam combining methods is beam combing based on nonlinear interaction. In our earlier work, we have demonstrated beam combining by multiplexing pulses in time, using second-order nonlinear crystal set in noncollinear phase-matching configuration. However, such configuration allows to scale only average power of the beam, leaving pulse energy unchanged (in case of 50 % conversion efficiency). In order to scale pulse energy and peak power, pulses have to be also combined in time, and for this, phase control is needed. Such approach was first proposed by Michailovas et al. and first proof of concept demonstrated by Zhang et al.. However, in previous demonstrations, low-power beams were combined with very low combining efficiency (<0.4 % for 4 beams). Here we apply this method to more realistic scenario and demonstrate combining of pulsed beams from 4 high-power fiber amplifiers with efficiency up to 49 %. Moreover, we demonstrate pulse energy and peak power improvement in the combined beam, exceeding peak-power limitations of single fiber amplifier.
关键词： noncollinear sum-frequency generation,fiber lasers,pulse energy scaling,peak power scaling,coherent beam combining
更新于2025-09-12 10:27:22
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Tapered erbium-doped fibre laser system delivering 10 MW of peak power
摘要： We consider a fibre laser system generating ~10-mJ, ~500-fs pulses with a peak power of ~10 MW at a repetition rate of 100 kHz and emission wavelength of 1.56 mm. The system is based on a master oscillator – power amplifier configuration. The amplifier ensures chirped-pulse amplification. The pulses are then compressed by a dispersive grating compressor. The output amplifier stage is based on a specially designed tapered large mode area erbium-doped fibre for suppressing nonlinear effects. The experimental data agree with numerical simulation results for the stretcher, amplifier and compressor. The stretcher and amplifier have been simulated using a generalised nonlinear Schr?dinger equation. In addition, numerical simulation results suggest that optimising the stretcher and compressor will potentially allow the peak power of the system to be scaled up to ~30 MW.
关键词： erbium-doped fibre amplifiers,tapered fibre,dispersive grating compressor,high peak power fibre laser systems,chirped-pulse amplification
更新于2025-09-12 10:27:22
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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) - SESAM Q-Switched 1534 nm Microchip Lasers: Pulse Duration, Repetition Rate, and Peak-Power Optimization for LIDAR Application
摘要： Q-switched 1.5 μm Er,Yb-doped microchip lasers are a particularly interesting class of lasers due to their monolithic design, small footprint, 976 nm diode pumping, on-board mass-producible architecture, and high pulse energy, enabled by the long upper-state lifetime of the gain material. Recently, the interest in these lasers has increased significantly due to the need for eye-safe LIDAR for drones, UAVs, rovers and autonomous cars. Various LIDAR applications have very different requirements for the pulse repetition rate, pulse energy, peak power and pulse width. In this work, we have explored the borders for the combination of these parameters by tailoring the properties of the Q-switching element, which is an InP-based semiconductor saturable absorber mirror (SESAM). In particular, we have put an emphasis for obtaining 10–100 kHz repetition rate in combination with 1–3 ns pulse width and preferably over 1 kW peak power. This set of target parameters was chosen as it could provide a reasonable compromise between positioning accuracy, speed of measurement and detectability of the signal. It should be noted, that simple, low-cost devices fulfilling these pulse specifications are currently not widely commercially available.
关键词： microchip lasers,repetition rate,peak-power optimization,pulse duration,SESAM,Q-switched,LIDAR
更新于2025-09-12 10:27:22
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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) - High Peak Power Laser Diodes for Eye Safe LIDAR with Integrated Wavelength Locking Element
摘要： We report on the development of high peak-power broad-area laser diodes emitting in the 1.5 μm wavelength band for eye-safe LIDAR applications. The laser contain a monolithically integrated surface grating section for wavelength stabilization. The performance merits of the wavelength stabilized laser is benchmark against traditional Fabry-Pérot diodes fabricated within the same processing batch and having identical quantum-well design. The study demonstrates the efficacy of the surface-grating applied to broad-area lasers and the benefits rendered possible for decreasing the spectral linewidth and reducing the temperature drift of the wavelength. This type of high-power light source can improve the signal-to-noise ratio of eye-safe time-of-flight LIDARs in bright illumination conditions by making possible the use of narrow band-pass filters for reducing the ambient sunlight. Moreover, the same advantage to reject ambient signal is expected in other applications such as gated imaging [1], or when using a pulsed laser as the illuminator in high speed imaging applications. In addition, the variation in the emission wavelengths from wafer-to-wafer and from chip-to-chip is reduced compared to non-stabilized lasers.
关键词： high peak-power,broad-area laser diodes,1.5 μm wavelength,wavelength stabilization,eye-safe LIDAR,surface grating
更新于2025-09-12 10:27:22