便携式脉冲调制型医用半导体激光器的驱动电源及光学透镜系统的设计

针对脉冲激光器穴位照射治疗的特点,对半导体激光二极管（LD）的驱动电路及光学镜头系统的设计进行了研究。本文设计了一款新型的锂电池供电便携式脉冲医用激光器,介绍了采用脉冲调制恒流驱动的原理以及采用透镜组和电路调整的方法改变激光照射功率密度的光学镜头的设计方法。该款脉冲激光器适用于激光体外穴位照射,对激光临床应用有一定的意义。     

用注入锁模法改善DFB激光器的频率响应

验证了通过注入锁模方法,分布反馈(DFB)半导体激光器的频率响应可以得到明显的改善.实验中通过一个环形器,将主激光器的输出光注入到从激光器.测量了从激光器在有注入光和没有注入光时的光谱和频率响应.发现在不同的注入光强度和波长下,激光器的调制带宽和弛豫振荡峰频率会发生变化.通过适当选择注入光的强度和波长,频率响应可以得到改善.激光器频率响应的改善可以用两个模式的拍频来解释,一个模式是从激光器的主模,另一个是主激光器的模式,该模式与从激光器的边带重合.该理论与实验结果符合得很好.     

医用激光的回顾与展望

本文评述了第一台红宝石激光器发明至今35年来医用激光的研究、发展和商品化概况,并展望它的未来,坚信医用激光将有极光明的前途.     

试析几种激光复合焊接技术

介绍了激光与其它热源进行复合焊接的几种方法,分析了这些复合焊接方法在保持激光焊接优点的基础上克服激光焊接缺陷的机理,最后指出这些复合焊接方法是激光焊接的一个发展趋势。     

真空激光熔覆的研究

真空激光熔覆避免了大气中有害气体对熔池的侵入,使熔覆层中的显微缺陷和开裂敏感性减小,提高了熔覆层的质量;并且真空熔覆的工艺特点与大气下的激光熔覆不完全相同;其它工艺条件相同时,真空激光熔覆的尺寸(宽度W和厚度H)明显小于大气下熔覆层的尺寸。     

Ytterbium laser with reduced thermal loading

We report a novel design for a high-power ytterbium disk laser. This laser utilizes radial diode pumping of a back surface cooled active-mirror geometry. Wing absorption of the pump light at 0.99 /spl mu/m allows efficient laser operation at 1.05 /spl mu/m with a low quantum defect. Laser performance and thermal loading were characterized for a wide range of conditions. Optimized operation of the laser yielded 490 W in a quasi-continuous-wave mode. Electrical efficiency of the laser was found to be 9.4%, while heating of the laser disk was only 3.2% of the absorbed optical power. Fluorescence re-absorption is identified as the principal heat generation mechanism in this laser. A simplified extension to the conventional rate model is proposed for lasing in radiation-trapped systems. This model allows power flow calculations in a radiation-trapped laser system using a single parameter determined from fluorescence decay waveforms. The revised model agrees with heat load measurements.     

Simultaneous Switching of the Q -Value and Operation Wavelength in an Erbium-Doped Fiber Laser

We report a pulsed erbium-doped fiber laser with simultaneous switching of the laser cavity Q-value and generation wavelength. The laser generates a train of short pulses with adjacent pulses alternately being on one of two fixed wavelengths. This regime is realized at periodical modulation of physical length of overwritten fiber Bragg gratings composing the laser cavity     

A cascade pumped picosecond dye laser system

A picosecond dye laser system producing 4 μJ in a 10 ps pulse is described. This highly stable compact system consists of a nitrogen laser and two cascade pumped dye laser oscillators followed by one amplifier. The Roess-Lin cavity transient technique was applied to compress the input 60 μJ 300 ps N2pulse twice to produce a final output duration of 10 ps. Discrete output wavelengths can be varied by changing the dye laser solution. Spectral and temporal measurements were performed to characterize this laser. A broad spectral emission of ∼ 160 cm^-1was observed, consistent with the observed fine temporal structures of 0.09 ps. A model rate equations calculation was also performed with parameters pertinent to the present laser system. This picosecond laser system should find applications in testing and calibration in the picosecond timescale.     

激光熔覆快速成形技术送粉喷嘴的研制

本文针对激光熔覆快速成形技术对送粉喷嘴的要求,分析了已有用于激光熔覆和激光熔覆快速成形技术送粉喷嘴存在的问题,研制了一种在以激光束为中心轴的圆周方向均匀对称分布四个具有同轴汇聚气的双层送粉管的送粉喷嘴.实验研究表明,此送粉喷嘴可以满足激光熔覆快速成形技术对送粉喷嘴的要求.     

Tuneable multiwavelength semiconductor laser with single fibre output

A new multiwavelength semiconductor laser with singlemode fibre output is reported. The laser consists of a semiconductor laser array which is incorporated into an external cavity comprising a diffraction grating and a fibre loop mirror. This laser has five wavelength-locked output channels with a fixed separation of 2.5 nm. The centre wavelength may be tuned over 80 nm.<>     

Carrier transport in laser heterostructures

We present two-dimensional numerical simulation of carrier transport in laser structures, which allows calculation of the efficiency of injected carrier consumption by the active region and the dependence of the laser current on applied voltage. It also allows calculation of the current, carrier, and potential distribution in a laser structure. This was done by use of PADRE, a program developed for the modeling of heterostructure electronic devices, which was supplemented with additional calculations of the laser optical properties. We applied this program to investigate the effect on the laser quantum efficiency of thermionic emission of electrons from the active layer. The temperature and current dependence of the laser internal quantum efficiency has been analyzed. This study allowed us to understand the performance of lasers with nearly ideal current-blocking structures     

Diode-pumped double passively Q-switched Nd:GdVO4 laser

Through using both Cr4 :YAG and GaAs saturable absorbers, a diode-pumped double passively Q-switched Nd:GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.     

激光危险性的分类及其对眼睛的影响

激光促进了许多领域的发展,但它也可对人体直接造成伤害。本文主要依据激光器输出光线的功率或系统所用的激光的能量对激光器进行了分类。论述了激光危险性的分类,激光对眼睛的影响及眼睛的防护标准。     

Diode-pumped double passively Q-switched Nd:GdVO4 laser

Through using both Cr^4＋：YAG and GaAs saturable absorbers, a diode-pttmped double passively Q-switched Nd：GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.     

激光在厚介质传输中的光电离动力学过程研究

研究了激光在厚介质中的传输特性以及激光与原子相互作用的光电离。推导了三步光电离的场方程组和原子布居的密度矩阵方程组。计算了在不同情况下电离几率与激光参数的变化关系。深入研究了激光在厚介质中传输引起激光参数的变化，以及激光功率、脉冲形状、脉冲宽度、三束激光的时间不同步对电离几率的影响。     

激光束波面畸变的全息诊断与补偿

本文报导一种补偿激光波面畸变的新方法。我们以象散光束为例,根据轴向全息图能够给出该光束补偿系统的状态。而且,利用双狭缝滤波和“交叉滤波”技术能够提取出具有位相调制或者是具有振幅起伏的近场波面。从而为在高功率激光系统中应用主动补偿象差技术提供了可能性。     

激光测距弱信号数字相关检测技术的研究和仿真

针对激光远程测距或恶劣环境测距中回波弱信号信噪比低 ,难以提取的困难 ,提出运用数字相关检测技术进行处理 ,并对单脉冲互相关、多脉冲互相关等数字处理技术作了介绍 ,并结合激光雷达的测距系统进行一系列仿真和计算 ,收到了良好效果     

A copper “HyBrID” laser of high-beam quality using anaxial unstable cavity

A 100 W copper “HyBrID” laser (CuHBr laser) fitted with an unstable cavity is examined in the far field and compared with a conventional copper vapor laser of similar beam dimensions. In the far field the divergence is about 100 μradians for the HyBrID laser. The copper vapor laser produces a slightly larger central divergence with significant high divergent structure. This is explained to be due to pulse shape and differences in radial variations of the gain onset timing of the two types of laser, improved beam quality is important for efficient pumping of titanium sapphire lasers and micromachining     

圆筒结构千瓦横流CO_2激光器

本文报道一台圆柱形结构横流CO_2激光器及其运转特性.圆筒长度1.45m,直径0.45m,已获得大于1kW的输出功率.     

FIR Laser Efficiency Enhancement by Double Resonance Tuning-Detailed Analysis

In a previous paper by the author (Ref. 1), FIR laser resonators with aperture coupling were shown to have resonance effect at the frequency that could be used to enhance the efficiency of the laser. This paper studies this effect over a wide range of laser parameters such as coupling aperture, cavity length and Fresnel Number. A set of curves are given to help a FIR laser designer optimize the laser.