Electro-optically Q-switched Nd:YVO4 slab laser with a high repetition rate and a short pulse width

We report on a compact and highly efficient diode-end-pumped TEM00 Nd:YVO4 slab laser with an output power of 103 W and beam quality M2 < or = 1.5. The optical-to-optical efficiency was 41.5%. In electro-optically Q-switched operation, 83 W of average power at a pulse-repetition rate of 50 kHz with a pulse length of 11.3 ns was obtained. At a pulse-repetition rate of 10 kHz, 5.6 mJ of pulse energy, and 870 kW of peak power were measured.     

Passively Q-switched Nd:YAG ceramic laser towards large pulse energy and short pulse width

A large pulse energy and high peak power passively Q-switched ceramic neodymium-doped yttrium aluminum garnet (Nd:YAG) laser has been demonstrated with Cr⁴⁺:YAG crystals as the saturable absorbers. By employing a continuous wave (CW) laser-diode (LD) as the pump source, as high as 11.3 W CW output power of 1064 nm was obtained under the pump power of 21.6 W, with an optical conversion efficiency of 52.3%. Inserting different initial transmissions Cr⁴⁺:YAG as saturable absorbers, under the incident pump power of 15.6 W, the largest pulse energy, shortest pulse width, and highest peak power are measured to be 188 μJ, 3.16 ns, and 59.5 kW, respectively. As we has known, this is the best passively Q-switched results ever reported by Nd:YAG ceramic material.     

Picosecond Nd:YLF five-passes laser amplifier with 20 mJ pulse energy

We have demonstrated an all-diode-pumped Nd:YLF laser amplifier that produces 20.8 mJ pulses of 12.9 ps duration at 10 Hz repetition rate. The laser system consists of a mode-locking oscillator, a regenerative amplifier and a five-pass amplifier. The small-angle off-axis five-pass configuration combining with the gradual expansion of the laser beam cross section makes the amplifier compact and effective.     

Diode-end-pumped 1D top-hat Nd:YVO4 slab laser

A one-dimensional (1D) top-hat, diode-end-pumped, electro-optically Q-switched Nd:YVO4 slab laser is demonstrated. Under the pump power of 175.5 W, 26.3-W output power is obtained with the repetition rate of 5 kHz and the pulse width of 4.3 ns. The output beam has a good top-hat beam profile in both the near field and the far field.     

Diode-pumped efficient slab laser with two Nd:YLF crystals and second-harmonic generation by slab LBO

We demonstrate a diode-pumped electro-optical Q-switched slab laser with a high optical efficiency, high pulse energy, and short pulse width with two Nd:YLF crystals inside one resonator. The single compact slab resonator can generate a 1D top-hat beam at both the far field and the near field. With a slab-geometry-design lithium triborate (LBO) crystal, efficient critical phase-matching second-harmonic generation for a 1D top-hat beam with multiple transverse modes is achieved.     

Diode-end-pumped CW and actively Q-switched Tm,Ho:YLF ring laser

This paper presents CW and acoustic-optical Q-switched Tm,Ho:YLF laser performance in a laser-diode end-pumping figure-eight ring resonator structure at 77 K. Under CW operation, different transmission of output couplers and different cavity length were used to achieve best characteristics of the laser. The maximum power of 1.85 W is achieved with the threshold of 2.09 W, slope efficiency of 28.14% and optical-to-optical efficiency of 20.3% on the condition of 1 m cavity length and 18% transmission. Under pump power of 4 W, laser characteristics under Q-switched operation with different pulse repeat frequency was investigated. Maximum energy of 5.86 mJ is achieved with pulse width of 171.2 ns, peak power of 34.2 kW and dynamic-static ratio about Q-switch laser of 0.62 at pulse repeat frequency 70 Hz.     

An automatically controlled Nd:YAG laser with variable pulse width

The development of a high-energy, pulsed Nd:YAG laser system for materials-processing and medical applications is reported here. A variable pulse width in the range of 0.3–10 ms and a variable pulse repetition rate up to 50 pps are provided. An automatic operation system using a microprocessor-based driver/ controller enables safe operation of the laser system and automatic material processing when integrated in a laser/robot system.     

An 110 W Nd:YVO4 slab laser with high beam quality output

In this paper we report on experimental results of an end-pumped Nd:YVO₄ slab laser with a hybrid resonator. 110 W output power with beam propagation factor M² of 1.3 and 1.5 in two orthogonal directions was obtained. After a spatial filter the typical beam propagation factors at 50 W operation were 1.09 and 1.2.     

激光二极管端面抽运室温Tm,Ho:YLF连续固体激光器

报道了激光二极管端面抽运Tm，Ho：YLF固体激光器的输出特性.室温下，选用不同透过率的输出耦合镜进行了实验研究，确定了最佳输出耦合镜透过率为2%. 利用小孔扫描的方法，得到了激光远场的光强分布，证明激光为基横模输出，并且给出了热焦距随抽运功率的变化关系.通过在激光谐振腔内插入两个固体Fabry-Perot标准具的方法，获得了2μm激光的单频输出，阈值功率为250mW，在抽运功率为2.8W时，单频输出功率为118mW.此单频激光器可用作激光振荡器和激光放大器的种子源. 关键词： 激光光学 激光二极管 Tm Ho:YLF固体激光器 单频     

Colliding pulse mode-locked Nd: YLF laser with negative feedback control by GaAs Photoconductive switch

A picosecond colliding pulse mode-locked Nd: YLF laser with negative feedback provided by GaAs photoconductive switch was described. Optical pulse with～4ps duration, 10μJ energy and about 7μs long pulse train were generated.     

MQW-LDA泵浦Nd:YLF激光器调Q的动力学过程及双机制作用

本文报道了国产多量子阱半导体激光列阵(MQW-LDA)泵浦Nd:YLF调Q脉冲脉宽.峰值功率与输出耦合率、泵浦速率、调制深度及延迟时间之间关系的实验,得到稳定的(起伏<1%)调Q脉冲输出,脉冲能量为0.8μJ,FWHM为70ns,脉冲重复率为100Hz,光-光效率2.5%;利用增益开关和Q开关双机制作用,压窄了调Q脉宽,提高了输出功率.用速率方程理论对过程计算,与实验结果较符合.     

A high energy, long pulse Nd: Yag laser multipass cell for raman scattering diagnostics

A new multipass cell design is proposed for use with high energy, pulsed lasers and for application to spontaneous Raman scattering diagnostics. Using a Nd: YAG laser pulse of 8 ns, 500 mJ at 1.06 μm, the frequency-doubled 60 mJ pulse is trapped in the multipass cell for 550 ns until it decays to 10% of its initial energy. This gives a resultant gain of 42 over the single pass case and corresponds to a multipass cell efficiency of 97.7% per pass.     

Self-adaptive Nd:YLF holographic laser with selectable wavelength operation

We demonstrate, for the first time to our knowledge, operation of a self-adaptive holographic laser with wavelength selection, which uses Nd:YLF as the gain medium. The holographic laser was self-starting and, by virtue of the temporal dynamics in writing the gain grating, passively Q-switched the cavity to produce pulses with 20–50 ns duration. A pulse energy of 184 mJ was obtained from the system with beams having a TEM₀₀ spatial profile. Single-longitudinal-mode operation was observed with near-transform-limited bandwidth. Received: 30 July 2002 / Revised version: 1 October 2002 / Published online: 26 February 2003 RID="*" ID="*"Corresponding author. Fax: +44-20/7594-7744, E-mail: s.y.lam@ic.ac.uk     

钕玻璃啁啾脉冲放大器产生百焦耳亚皮秒脉冲

以钕玻璃为增益介质研制了高能啁啾脉冲激光放大器系统,实验演示输出啁啾脉冲能量在百焦耳量级时,光谱宽度保持在4—6 nm.最大能量168 J,相应谱宽5.5 nm,中心波长1054 nm.压缩脉冲宽度最短710 fs. 关键词： 啁啾脉冲放大 钕玻璃 高能拍瓦     

Diode-end-pumped passively mode-locked Nd:GGG laser with a semiconductor saturable mirror

We report on the passive mode-locking of a diode-end-pumped neodymium-doped gadolinium gallium garnet (Nd:GGG) crystal with a semiconductor saturable absorber mirror (SESAM). Continuous wave (CW) mode-locking was obtained. The mode-locked pulse duration was estimated to be ∼17.5 ps with a maximum average output power of 0.4 W. The mode-locked pulses have a repetition rate of 121.5 MHz. To our knowledge, this is the first demonstration of passive mode-locking of the diode pumped Nd:GGG lasers.     

High efficiency and good beam quality of electro-optic, cavity-dumped and double-end pumped Nd:YLF laser

In this paper, we describe a Nd:YLF laser based on high-speed RTP electro-optical cavity dumping technique. Two home-made 150 W fiber pump modules are used from both sides to pump Nd:YLF crystal. Coupling systems are the key elements in end-pumped solid-state lasers, the aberrations of which greatly affect the efficiency of the lasers. In order to get high efficient and good quality laser output, the optical software ZEMAX is used to design a four-piece coupling system. When the pumped energy is 32 mJ at the repetition rate of 1 Hz, the output energy is 6.5 mJ with 2.5 ns pulse width. When the pumped energy is 13.1 W at the repetition rate of 200 Hz, the output energy is 2.2 W with small M ² factor where M _x ² is 1.04, and M _y ² is 1.05, and the light-light conversion efficiency is up to 16.8%.     

Mathematical modelling of an Nd: YAG laser: peak power and pulse width

In a previous paper, the author presented an empirically derived mathematical model of a pulse pumped laser which allowed calculation of the output energy from the laser—from the mirrors-only resonator to the fully assembled Q-switched state. In this paper the model is developed further by deriving an expression for the peak output power. New coupling and loss time constant are stated. The validity of the model is demonstrated by the ability of calculate the laser parameters from a measured pulse shape, knowing the rod dimensions and the pump energy at which the pulse was measured.     

Diode-end-pumped passively mode-locked Nd:LuVO4 laser with a semiconductor saturable-absorber mirror

A diode pumped passively mode-locked Nd:LuVO₄ laser with a semiconductor saturable-absorber mirror (SESAM) is demonstrated. The mode-locked pulses have a pulse duration of about 8.8 ps and a repetition rate of 157 MHz. Under an absorbed pump power of 12 W a maximum output power of 3.71 W is obtained, which gives an optical conversion efficiency of 31%. Our results show that Nd:LuVO₄ is a promising gain medium for the high power mode-locked solid-state lasers.