Analysis on a new type magneto-optical disk for blue lasers

The conventional TbFeCo magneto-optical (MO) medium has a relatively smaller Kerr rotation angle in the blue region than in the red. With the recording wavelength gradually moving to the short wavelength, if TbFeCo is still used as recording medium, the conventional MO disk structure must be optimized to get a larger carrier to noise ratio (CNR). Sabi et al. have found that adding a metal layer attached to the TbFeCo film as thermal control layer is a useful way to get a high CNR. In this paper, we proved this through calculation, and carried out optimization of the new type of disk. Calculation results showed that the new structure is useful in preventing an excessive temperature increase, and has a better thermal response. (c) 2005 Elsevier B.V. All rights reserved.

固体拉曼激光器

简要介绍了固体拉曼激光器的研究现状，总结了几种常用的同体拉曼晶体[LiIO3，Ba(NO3）2，CaWO4]的受激拉曼实验特性，并对如何设计各种形式的拉曼激光装置以取得良好的频率转换做了分析。最后对同体拉曼激光器的发展做了展望。

板条激光放大器中寄生振荡的研究

寄生振荡的存在使得放大器在信号光到达之前消耗了大量的反转粒子数,降低了放大器的激光增益和储能效率,严重地影响了激光放大器的性能,尤其对高功率激光放大器。在理论分析和实验研究的基础上,以Nd∶YAG晶体板条为例,用8条半导体激光阵列对晶体进行双侧抽运,研究了高功率激光放大器的寄生振荡现象,分析了板条晶体寄生振荡产生的原因,并详细比较了晶体在不同的抽运功率和表面处理下的放大效果,得到了2倍的单程放大,当输入能量为140 mJ时,获得了278 mJ的激光输出。

侧面抽运国产Nd∶YAG陶瓷棒的激光特性

实验研究了激光二极管阵列(LDA)侧向抽运国产Nd∶YAG陶瓷棒的准连续及被动调Q激光输出特性。该陶瓷激光器采用LDA侧面紧密环绕均匀排布的抽运结构,陶瓷棒抽运区域长度为20 mm,其总尺寸为3 mm×35 mm,掺杂原子数分数为~1%。在千赫兹准连续运转条件下,当平-平谐振腔的输出耦合镜透过率为47.3%时,获得最大平均功率23 W的1064 nm激光输出,光束发散角为4.5 mrad,斜率效率达12%。在谐振腔内插入Cr4+∶YAG晶体作为被动调Q开关,成功地实现了陶瓷激光器千赫兹重复频率调Q激光脉冲输出,当Cr4+∶YAG晶体初始透过率为60%时,输出激光脉冲宽度(半峰全宽)可窄至14.5 ns,调Q动静比约为40%。

Output beam quality of edge pumped planar waveguide lasers with confocal unstable resonators

Output beam quality of edge pumped planar waveguide lasers with confocal unstable resonators is investigated by diffraction methods, taking into account gain saturation, asymmetric pumping, and beam interaction. The influences of pumping uniformity, doping concentration, cavity length and effective Fresnel number are analyzed with respect to output beam quality and pumping efficiency. It is found that good beam quality and high efficiency can be obtained with asymmetric pumping and optimized negative branch confocal unstable resonators. (c) 2005 The Optical Society of Japan.

Experimental study of Ti : sapphire laser end-pumped Nd : YAG ceramic laser Q-switched by Cr4+: YAG saturable absorber

By employing a continuous-wave (CW) Ti:sapphire tunable laser as a pumping source and a Cr4+:YAG single crystal as the saturable absorber (SA), a passively Q-switched Nd:YAG ceramic laser has been demonstrated at room temperature. With an absorbed pumping power of 541 mW at 808 nm, an average output power of 61 mW at 1064 nm has been obtained with 3.5 mu J pulse energy, 15 ns pulse width and 18.18 kHz repetition rate, and the corresponding slope-efficiency is 15%. The relationships between the pulse width, repetition rate, average output power, pulse energy, and peak power on the absorbed pumping power for different initial transmission of the Cr4+:YAG SA are discussed separately. The Nd:YAG ceramic is one of the most promising laser materials for compact, efficient, all-solid-state pulsed lasers.

High power coherent beam combination from two fiber lasers

Phase locking of two fiber lasers is demonstrated experimentally by the use of a self-imaging resonator with a spatial filter. The high-contrast interference strips of the coherent beam profile are observed. The coherent output power of the fiber array exceeds 12W and the efficiency of coherent power combination is 88% with pump power of 60W. The whole system operates quite stably and, for the spatial filter, no thermal effects have been observed, which means that we can increase the coherent output power further by this method. (c) 2006 Optical Society of America

Nd-glass belt lasers with improved beam quality

Nd-doped phosphate glass belt lasers pumped by laser diodes are demonstrated. The Nd-glass belt with a large cross-section and a small Fresnel number is air-cooled to provide around 18-W continuous wave (CW) output power with a beam quality factor of My2

Phase-locking of two large-core fibre lasers with 60W of coherent output power

A phase-locking fibre laser array with up to 60 W of coherent output power based on two large-core fibre is reported. The slope efficiency of the in-phase mode is 37%. For two cases of spacings between the cores, steady high-contrast interference stripes are observed. When the whole system operates under a high pump power level, no thermal effects for the spatial filter have been observed, which means that we can increase the coherent output power further by increasing the individual fibre laser power.

Quasi-self-imaging planar waveguide lasers with high-power single-mode output

We describe high-power planar waveguide laser which can achieve single-mode output from a multi-mode structure. The planar waveguide is constructed with incomplete self-imaging properties, by which the coupling loss of each guided mode can be discriminated. Thermal lens effects are evaluated for single-mode operation of such high-power diode-pumped solid-state lasers. (c) 2005 Elsevier B.V. All rights reserved.