研究并求解了热效应条件下的半导体激光器的速率方程。在经典速率方程的基础上, 通过引入热效应特性, 得到了带温度参量修正的速率方程组, 然后利用Simulink软件工具, 对该非线性微分方程进行仿真求解, 最后以某分布反馈激光器的参量为例, 得到了不同偏置点、不同调制信号及不同温度条件下速率方程的瞬态解, 并据此分析了弛豫振荡、频率啁啾等特性。仿真求解结果符合该型激光器的瞬态特性, 为该型激光器设计制造和应用选型提供了一定的参考。
半导体激光器 速率方程 瞬态特性 弛豫振荡 频率啁啾 semiconductor laser rate-equation transient performance relaxation oscillation frequency chirp Simulink Simulink
Author Affiliations
Abstract
1 Zhejiang University, College of Optical Science and Engineering, State Key Laboratory of Modern Optical Instrumentation, Hangzhou, China
2 Nanjing University of Aeronautics and Astronautics, Institute for Advanced Interdisciplinary Research, Nanjing, China
3 Hunan University of Science and Technology, School of Physics and Electronic Science, Xiangtan, China
Real-time spectroscopy based on an emerging time-stretch technique can map the spectral information of optical waves into the time domain, opening several fascinating explorations of nonlinear dynamics in mode-locked lasers. However, the self-starting process of mode-locked lasers is quite sensitive to environmental perturbation, which causes the transient behaviors of lasers to deviate from the true buildup process of solitons. We optimize the laser system to improve its stability, which suppresses the Q-switched lasing induced by environmental perturbation. We, therefore, demonstrate the first observation of the entire buildup process of solitons in a mode-locked laser, revealing two possible pathways to generate the temporal solitons. One pathway includes the dynamics of raised relaxation oscillation, quasimode-locking stage, spectral beating behavior, and finally the stable single-soliton mode-locking. The other pathway contains, however, an extra transient bound-state stage before the final single-pulse mode-locking operation. Moreover, we propose a theoretical model to predict the buildup time of solitons, which agrees well with the experimental results. Our findings can bring real-time insights into ultrafast fiber laser design and optimization, as well as promote the application of fiber laser.
fiber laser mode-locking self-starting process relaxation oscillation real-time spectroscopy Advanced Photonics
2019, 1(1): 016003
1 中国科学院西安光学精密机械研究所, 西安 710119
2 青岛海洋科学与技术国家实验室, 山东 青岛 266237
对采用相位生成载波解调的光纤激光水听器系统中3 kHz附近频域内固有噪声的产生机理进行了理论推导, 并设计实验进行验证.首先测量得到泵浦激光器的驰豫振荡频率峰值, 随后以400 Hz为间隔逐渐降低相位生成载波信号频率, 观察固有噪声峰值的移动方向和大小.实验结果表明, 随着载波信号频率的降低, 固有噪声峰也向低频方向移动, 移动间隔同样为400 Hz.可知相位生成载波解调算法中高频载波调制信号与泵浦激光器的驰豫振荡频率叠加是形成探测频谱固有噪声的主要原因.通过降低高频载波调制信号频率的方法对驰豫振荡噪声进行抑制, 消除了探测频谱中的固有噪声峰, 得到了较为平坦的本底噪声谱.
光纤光学 光纤激光水听器 分布反馈光纤激光器 相位生成载波 驰豫振荡 Fiber optics Fiber laser hydrophone Distributed feedback fiber laser Phase generated carrier Relaxation oscillation
上海理工大学 光电信息与计算机工程学院, 上海 200093
聚合物分散液晶全息光栅具有电场可调的特点,材料中掺杂纳米银颗粒, 能够有效降低光栅的驱动电压.由于聚合动力学的影响, 会造成纳米银颗粒在光栅中的非均匀分布, 即纳米银在聚合物和液晶区分布含量不均匀, 表现出不同的电场调控特性.通过等效电路建模的方法研究驱动电压阈值与所施加交流电场的频率之间的关系.根据Maxwell-Wagner效应建立纳米银分别被液晶和聚合物包围的等效电路模型, 具体研究在液晶条纹中, 纳米银含量占总纳米银比例不同的条件下, 纳米银掺杂的聚合物分散液晶全息光栅的介电弛豫时间和弛豫振荡的频率数值变化, 进一步调节驱动电场频率, 获得更低的驱动电压阈值.通过最优驱动电场频率范围来初步确定纳米银在光栅中的分布结构, 并证明纳米银颗粒集中在液晶条纹, 少量分布在聚合物条纹中.
聚合物分散液晶全息光栅 弛豫振荡频率 阈值驱动电压 非均匀分布 holographic polymer dispersed liquid crystal relaxation oscillation frequency threshold driving voltage non-uniform distribution
海军工程大学兵器工程系, 湖北 武汉 430000
激光器的弛豫振荡带来的强度噪声对分布反馈式光纤激光水听器的系统噪声有较大影响。分析了该强度噪声在NPS算法数字实现中的传递过程, 发现求导运算的非理想特性是解调结果中引入强度噪声的原因。提出了一种改进的NPS算法, 使强度噪声在进入求导运算前被抵消, 消除了强度噪声传递到解调结果中的途径。实验结果表明, 当弛豫振荡峰处相对强度噪声为-84 dB·Hz-1时对解调相位噪声的抑制在1 kHz处达到了30 dB。将改进后算法与不需要求导运算的反正切法进行了对比, 进一步验证了其可抑制求导所引入的强度噪声。
传感器 光学传感 弛豫振荡 3×3耦合器 数字解调 分布反馈式光纤激光水听器 中国激光
2017, 44(10): 1010001
南京大学 现代工程与应用科学学院, 江苏 南京 210000
为了改善内腔连续光参量振荡器(IC-OPO)输出功率不稳定, 弛豫振荡严重等问题, 对IC-OPO进行了改进: (1) 采用热透镜补偿设计, 改善模式匹配; (2) 使用光阑限模, 抑制高阶模振荡; (3) 在腔内加入KTP晶体, 利用二次谐波产生(SHG)过程的非线性损耗抑制弛豫振荡。通过改进, 获得了稳定的紧凑型2.2～4.2 μm的可调谐连续波中红外光源。输出功率波动标准偏差(RMS) 0.52%, 峰值波动范围1.8%, 光束质量因子M2=1.72, 弛豫振荡得到有效抑制。当腔内不加入KTP晶体时, 阈值(808 nm)仅为1.5 W。据笔者所知, 该阈值为国内相关工作报道中的最低值。
光参量振荡器 内腔 连续波 弛豫振荡抑制 OPO intra-cavity continuous-wave relaxation-oscillation suppression 红外与激光工程
2017, 46(4): 0406004
1 中国科学院长春光学精密机械与物理研究所发光学及应用国家重点实验室, 吉林 长春 130033
2 中国科学院大学, 北京 100049
基于激光器的增益理论和动态理论, 结合经典的激光器速率方程, 分析了激光器有源区尺寸、光纤光栅结构、耦合效率和注入电流等参数对频率噪声和弛豫振荡频率的影响。以获得低频率噪声和高驰豫振荡频率为目标, 进行数字仿真, 仿真结果表明, 较小的激光器有源区尺寸、较强的外腔光反馈和较高的注入电流有利于改善噪声特性, 其中注入电流的影响尤为重要。当注入电流为阈值电流的9倍时, 频率噪声降低约14.7%, 弛豫振荡频率增加约6.0 GHz。
激光器 半导体激光器 外腔 光纤光栅 频率噪声 弛豫振荡频率 激光与光电子学进展
2017, 54(1): 011401
为了降低半导体抽运固体激光器的弛豫振荡噪声, 提高其输出功率的稳定性, 采用光电负反馈的方法来抑制半导体抽运的固体激光器的强度噪声, 并对激光器强度噪声的理论特性进行了分析。根据理论分析结果设计了比例-积分-微分反馈控制电路, 通过运用该反馈电路对激光器进行强度噪声抑制实验, 得到了比较理想的实验数据, 即当抽运功率为700mW、弛豫振荡峰频率为300kHz时, 弛豫振荡峰值处和低频区域强度噪声分别降低了45dB和15dB; 当抽运功率为550mW、弛豫振荡峰值为250kHz时, 弛豫振荡峰值处和低频区域强度噪声分别降低了40dB和10dB。结果表明, 该反馈控制电路能够有效地降低半导体抽运固体激光器的强度噪声, 提高激光器输出功率的稳定性。
激光器 强度噪声抑制 光电负反馈 弛豫振荡 lasers intensity noise suppression photoelectric negative feedback relaxation oscillation
Author Affiliations
Abstract
1 School of Information Science and Engineering and Shandong Provincial Key Laboratory of Laser Technology and Application, Shandong University, Jinan, 250100, China
2 Laser Institute of Shandong Academy of Science, Jinan, 250014, China
3 Photonics & Optical Communications Group, School of Electrical Engineering & Telecommunications, the University of New South Wales, Sydney 2052, Australia
A sensor array system formed by arranging four asymmetric distributed-feedback fiber lasers (DFB-FL) in ascending order according to their slope efficiencies was proposed. The output flatness could be effectively improved with the application of asymmetric DFB-FLs. The last element had almost the same output with the others although it obtained the smallest pump power. The relative intensity noise (RIN) and relaxation oscillation frequency of the sensor array were also analyzed. It is found that the relaxation oscillation frequency of a certain DFB-FL was relevant to its relative position in the array. And the RIN of a certain DFB-FL was always affected by the other elements in the array, which was not dependent on the order of their arrangement.
Asymmetric DFB fiber laser sensor array intensity noise relaxation oscillation Photonic Sensors
2014, 4(2): 180
