Effect of temperature on refractive index match of laser glass edge cladding

An Nd：glass disc requires an edge cladding to absorb the amplified spontaneous emission. The absorption is determined by reflections （R） from disc edges. R is primarily induced by the refractive index （n） mismatch. Thus, the temperature at the cladding interface increases due to absorption, and leads to the variation of n. In order to investigate the effect of temperature on the refractive index match, temperature coefficients （dn/dT） of the laser glass, adhesive polymer, and cladding glass are measured. The effect of temperature on the refractive index match is discussed. Results show that the indices match below 40 ℃.     

双势阱中原子质心运动对自发辐射的抑制

研究了一个囚禁于对称双势阱中的二能级原子与单模腔场的相互作用.通过求解薛定谔方程,给出了整个系统波函数解析解和原子能级粒子数反转的解析表达式.分析了当腔场初始态分别为粒子数态、相干态以及热态时原子粒子数反转随时间的演化情况,并考虑了原子质心运动对粒子数反转的影响.结果表明通过选择合适的腔场初始态、势阱位置及相关因素,可以有效地控制原子的自发辐射率.     

少模光纤放大器模式竞争及信噪比的研究

将信号模场和增益离子横向分布函数引入功率传输方程，采用多环法计算少模光纤放大器中信号及ASE的传输放大。研究增益离子分布对模式竞争和信噪比(SNR)的影响。对照模型改进前后结果，给出两种模型各自适用范围。结果表明，信号填充因子是表征不同模式在竞争中强弱地位的有效指标。增益离子集中掺杂有利于基模的放大和高阶模的抑制；集中均匀掺杂60%-70%较利于基模选择；随着掺杂范围趋于集中，ASE显著降低，信噪比逐渐提高。     

抽运光中ASE噪声对OPCPA信噪比的影响

惯性约束核聚变快点火实验,要求拍瓦终端输出再压缩的高信噪比超短激光脉冲.在拍瓦前端光参变啁啾脉冲放大(OPCPA)阶段,抽运激光脉冲中由放大的自发辐射(ASE)噪声调制导致的电场强度振幅和相位的随机扰动.将会被传递到信号光的光谱E.使再压缩后主激光脉冲前后出现底座.降低了信号光的信噪比.数值模拟了抽运激光脉冲中ASE噪声对信噪比以及对时间底座的宽度的影响,并探讨了有利于提高超短激光脉冲信噪比的途径.     

基于EDFA的分布式光纤喇曼温度解调技术

为了消除掺铒光纤放大器的放大自发辐射噪声对分布式光纤温度传感器测温精度的影响,采用精确的修正公式进行温度解调是一种有效手段。通过分析掺铒光纤放大器的放大自发辐射噪声对系统产生的影响,并将计算的中间结果代入理论公式获得了修正后的温度解调公式。实验中分别采用理论公式和修正公式对温度进行分布式测量并获得了实验数据。结果表明,修正后的温度解调公式有效补偿了掺铒光纤放大器噪声引起的误差,并显著提高了系统的信噪比和测温精度;修正公式可将系统的整体测温精度提高到1℃～2℃;此外,实验中观察到多模光纤中喇曼背向自发散射同样会出现放大现象,这与单模光纤中的情形类似,且放大喇曼自发散射依然具有理想的温度效应。     

加长棒脉冲钕玻璃激光器异常实验现象理论研究

以激光原理为基础, 以大量精确的实验数据为依据;考虑被忽略的自发辐射的影响, 对加长到抽运腔外的钕玻璃棒, 未受到抽运, 反而产生光放大异常实验现象的机理进行了理论研究.理论研究结果与实验结果基本相符.     

A theoretical model of thulium-doped silica fiber＇s ASE in the 1900 nm waveband

A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in...     

Spontaneous emission of two quantum dots in a single-mode cavity

The spontaneous emission spectrum from two quantum dots （QDs） that are strongly coupled with a single-mode nanocavity is investigated using rigorous numerical calculations and simple analytical solutions of quantum dynamics. The emission spectra both from the side and along the axis of the cavity are considered. Modification of two parameters, the coupling strength and the detuning between the transition frequencies of the two quantum dots, allows us to efficiently control the shape of the spontaneous emission spectrum. Different profiles and their physical origins can be well understood in the dressed-state picture for the light-QD interaction in the on-resonance and off-resonance situations. In the on-resonance situation, the emission spectra exhibit symmetric features, and they are not altered by the asymmetry in the coupling pa- rameters. The axis spectra show two emission peaks while the side spectra have three emission peaks. In the off-resonance situation, the emission spectra always show an asymmetrical three-peak feature. When the two QDs have different decay parameters, singular features （a peak or a dip） can take place at the frequency of the cavity mode, and this is attributed to the unbalanced process of the emission and absorption of a single photon.