光纤光栅外腔半导体激光器的高频调制特性

报道了光纤光栅外腔激光器瞬态特性的理论分析,引入了一个适用于外腔情况的等效光子寿命,模拟计算表明,要获得高于2．5GHz的调制速率,光纤光栅外腔的长度必须短于4cm范围,对所研制的光纤光栅外腔激光器进行了高频调制测量,得到了在1GHz下的单模激光输出,边模抑制比在40dB以上,3dB动态线宽为0．1nm左右,20dB动态线宽为0．3nm。     

Influence of thermal effect on multi-junction GaInP/GaAs/Ge concentrating photovoltaic system

<正>The influence of thermal effect on the energy conversion efficiency of concentrating photovoltaic system for multi-junction GaInP/GaAs/Ge thin-film solar cell is analyzed experimentally.With the increment of operation temperature,the maximal energy conversion efficiency and optimal loaded resistor will be changed.Under the condition of operation temperature lower than 90℃.this influence of thermal effect is very small.However,when the operation temperature exceeds 90℃,the maximal conversion efficiency of the cells will decrease sharply,and contrarily the corresponding optimal loaded resistor will increase quickly.Then the system performance will degenerate badly and a thermal management will be necessary.     

Characteristics of a PLZT electro-optical deflector

A beam deflector was designed and fabricated by using a lead lanthanum zirconate titanate(PLZT)ceramic with high quadratic electro-optic(EO)effect,based on refraction at an interface between areas with and without applied voltage.Its EO coefficients of R33=2.1×10~(-16)V2/m~2 and R_(13)=-0.37×10~(-16)V~2/m~2 were obtained.Moreover,the hysteresis characteristics of the EO deflection were observed,and the effects of temperature on the characteristics of beam deflector were also investigated in detail.     

Channel spacing halving and multi-channel apodisation of sampling fiber Bragg grating based on Moiré effect

Channel spacing halving and multi-channel apodisation of sampling fiber Bragg grating (SFBG) based onSFBG. The experiment and theoretical analysis showed that the channel spacing could be halved whenfringe was twice the length of SFBG and the initial phase difference of two exposures was odd times of π.A novel method to control the initial phase difference of two exposures is presented in this paper. Usingthis technique, we fabricated two SFBGs with channel spacing of 50 and 100 G by a same phase mask andan apodized SFBG with channel spacing of 100 G.     

光纤光栅外腔分布布拉格反射激光器中的波长转换

报道了一种新型的基于光纤光栅外腔分布布拉格反射激光器的波长转换技术，获得了８ｎｍ的波长转换间隔，对注入信号的灵敏度、转换信号之间的反相特性等进行了测量研究。讨论了波长转换的机理和该技术的特点和优点。     

Characteristics of an add-drop filter composed of a Mach-Zehnder interferometer and double ring resonators

A planar lightwave circuit (PLC) add-drop filter is proposed and analyzed, which consists of a symmetric Mach-Zehnder interferometer (MZI) combined with double microring resonators. A critical coupling condition is derived for a better box-like drop spectrum. Comparisons of its characteristics with other schemes, such as a MZI with a single ring resonator, are presented, and some of the issues about device design and fabrication are also discussed.     

长周期光纤光栅和双锥形光纤问的倏逝波耦合作用

对长周期光纤光栅和双锥形光纤之间的倏逝波耦合作用进行了研究。理论分析和实验研究表明，由于锥形光纤和长周期光纤光栅物理边界外倏逝波之间的交叠，长周期光纤光栅产生的包层模，可以耦合到锥形光纤的包层模并从锥形光纤的纤芯输出。要获得高的耦合效率，应满足模式匹配的条件，同时要尽量减小两光纤之间的距离。耦合特性还与长周期光栅和双锥形光纤的相对位置有关，为获得高的耦合效率，耦合区应位于长周期光栅区的后面。这种倏逝波耦合作用，为监测实际应用系统中长周期光纤光栅的特性提供了一种新方法；为利用锥形光纤和长周期光纤光栅开发新型光纤器件，提供了一种可能的方案。     

全光纤调Q掺铒光纤激光器的脉冲研究

报道一种全光纤调Q掺铒光纤激光器,在其结构中采用带有光纤光栅的光纤环形镜作为调Q装置此调Q方案同时具有对腔内损耗进行调制和对激光输出波长选择的功能理论上分析了不同臂长差时的脉冲出现情况,与实验基本相符并对激光单脉冲产生及稳定性进行了分析讨论.     

光纤光栅带内色散特性的离散时域分析

采用多层介质的离散传输线模型表型光纤光栅响应特性，并利用数字信号处理方法对光纤光栅的相位特性进行了分析，研究了用于密集波分复用窄带滤波的变迹光纤光栅的带内色散特性，表明对称变迹光纤光栅的幅度响应与相位响应之间满足希尔伯特变换关系，幅度响应越接近理想的矩形，带内色散越大。并采用耦合模理论数值计算了对称变迹的光纤光栅的反射相位响应和带内群时延情况，验证了分析结果。     

体布拉格光栅外腔半导体激光器光谱特性研究

用体布拉格光栅(VBG)作为反馈元件与瓦级半导体激光器(LD)以及快轴准直柱透镜构成一个可以将半导体激光器的工作波长稳定在体布拉格光栅布拉格波长处的外腔激光器。测量了体布拉格光栅外腔激光器的波长稳定性与其工作电流、热汇温度、激光束准直装置等因素的关系。分析了波长稳定效果与半导体激光器增益谱特性、外腔结构参量等因素的关系。研究表明,在相同的工作电流、热汇温度下,当准直柱透镜直径为0.4 mm时的波长稳定效果较好;在此情况下,当热汇温度控制在30℃,工作电流从0.5 A增加到1.5 A的测量范围内,以及当工作电流固定在1.5 A,热汇温度从20℃增加到35℃时,测得的光谱特性表明,半导体激光器的工作波长可以很好地稳定在体布拉格光栅的布拉格波长处。与该激光器在同样条件下自由运转的光谱比较,可以看到,自由运转激射波长与体布拉格光栅的布拉格波长差值小于2.6 nm情况下,可以获得很好的波长稳定效果。实验也表明,当该值大于4.8 nm时波长稳定效果变差。