半导体激光器参量估计的改进算法

为了精确估计带外腔半导体激光器的线宽展宽因数,采用了光反馈自混合技术和梯度最优算法,可以达到数据-理论的最佳拟合,同时提出了改进的梯度迭代公式,并在参量迭代时引入可变步长,取得了仿真和实验数据.该算法不仅测量精度较高,而且抗噪声性能较好.仿真结果表明,当信噪比大于20dB时,线宽展宽因数的相对标准差小于2.55%.实验数据处理结果表明,线宽展宽因数的相对标准差小于5.1%,对半导体激光器的应用是有帮助的.     

Littrow型光栅外腔半导体激光器的输出特性分析

在讨论光栅外腔半导体激光器理论的基础上.对影响Littrow型光栅外腔半导体激光器输出功率和线宽压窄的各种因素进行了数值模拟分析.研制了单纵模高质量激光输出的Littrow型光栅外腔半导体激光器,在工作电流为400 mA时,连续输出功率达到180 mW,线宽优于1 MHz.     

低阈值光纤激光器稳频特性研究

为了实现低阈值光纤激光器的频率稳定输出,设计了环形腔光纤激光器,以光纤光栅作为波长选择元件,在未泵浦光纤饱和吸收体和其锥形化结构的协同作用下实现激光纵模选择,获得了短光纤饱和吸收体长度下的单纵模激光稳定输出。介绍了未泵浦光纤饱和吸收体选频原理和锥形结构滤波原理,实验研究了不同光纤饱和吸收体长度下激光纵模特性和波长稳定性,以及锥形化光纤饱和吸收体的激光输出特性。实验表明,引入锥形化结构的饱和吸收体后,激光器能够稳定输出1545 nm波长的单纵模激光,并有效降低光纤激光器阈值至7.58 mW,采用延迟自外差方法测得该光纤激光器的线宽小于8 kHz。     

Temperature dependence of the linewidth of the first-order Raman spectra for MnF2 crystal

The first-order Raman spectra ofE _gandA _1g modes in MnF₂ crystal were measured at temperatures from 4.2 to 563 K, and the values of the linewidths obtained. The temperature dependence of the linewidths was analyzed by the phonon dispersion curves based on the rigid ion model, and the result showed that it was caused approximately by the cubic anharmonic term in crystal potential energy.     

Effect of Linewidth Enhancement Factor on Doppler Beat Waveform Obtained from a Self-Mixing Laser Diode

The asymmetry and fringe inclination of the sawtooth-like waveform observed in the self-mixing signal obtained from a semiconductor laser with optical feedback enable the direction discrimination of line-of-sight motion of external target surfaces. We investigated the effects of linewidth enhancement factor and feedback strength on the asymmetry and the direction of fringe inclination of the signal by numerical simulations. For the first time, we show that direction of the fringe inclination is determined not only by the direction of the target motion but also by the value of the linewidth enhancement factor.     

半导体激光器的线宽压窄及频率连续调谐

我们利用共焦F—P腔光学弱反馈技术，实现了单模GaAlAs半导体激光器线宽压窄、频率锁定及连续调谐。其线宽从自由运转时的10MHz被压窄到45kHz，并可将频率锁定于共焦F—P腔。实验证明，在弱反馈情况下，激光器的频率连续调谐范围与共焦FP腔的光强反馈量近似成正比，实现了在铷原子D2线附近1．2GHz的频率连续调谐，     

超短脉冲激光系统中用于光谱整形和群延迟控制的可编程声光色散滤波器

介绍了一种利用声光相互作用对超短脉冲激光系统中的增益窄化和群延迟色散等进行补偿的装置——可编程声光色散滤波器(AOPDF）。其基本思想最初南法国的P.Tournois提出,后来开发了商业化的产品Dazzler装置,并在世界其他国家的超短脉冲激光装置中得到了广泛的应用。本文从AOPDF的基本原理以及耦合波方程出发,旨在向读者全面地介绍AOPDF中声光相互作用的过程以及对群延迟的控制。     

高稳定度窄线宽激光器的研究

介绍了3种不同类型的高稳定度窄线宽激光器的研究进展.基于Littman结构和饱和吸收光谱稳频技术,研制了稳频外腔半导体激光器系统,输出波长为780.2 nm,频率稳定度1 MHz,不失锁时间大于12 h.利用边带稳频技术将分布反馈(DFB)激光器的输出波长稳定在Cs原子的吸收谱线的边带处,引入数字信号处理器(DSP)全数字稳频控制技术,实现了自动找频和稳频,获得波长为852.3 nm的稳频激光输出,24 h内频率漂移为±2 MHz.利用国产磷酸盐玻璃光纤作为增益介质,实现了一台高功率单纵模光纤激光器,制作的厘米级激光器实现了最大输出功率100 mW,利用外部光反馈实现单偏振运转,测得输出线宽为2 kHz,偏振消光比优于35 dB.     

主振荡功率放大结构窄线宽全光纤激光器334 W高功率输出

搭建了一台全光纤结构的窄线宽高功率掺镱光纤激光器。种子激光的输出功率大于40 mW,线宽窄于100 MHz。采用主振荡功率放大结构三级放大,主放泵浦功率为405 W时得到了334 W的窄线宽高功率激光输出,光光转换效率为82.4%。目前,激光器输出功率仅受限于泵浦功率,增加有效泵浦功率即有望进一步提高输出功率。     

Exciton fine structure splitting of single InGaAs self-assembled quantum dots

We show how the resonant absorption of the ground state neutral exciton confined in a single InGaAs self-assembled quantum dot can be directly observed in an optical transmission experiment. A spectrum of the differential transmitted intensity is obtained by sweeping the exciton energy into resonance with laser photons exploiting the voltage induced Stark-shift. We describe the details of this experimental technique and some example results which exploit the 1 μeV spectral resolution. In addition to the fine structure splitting of the neutral exciton and an upper bound on the homogeneous linewidth at 4.2 K, we also determine the transition electric dipole moment.