非即变相位共轭反馈对半导体激光器动态特性的影响

从四波混频产生相位共轭的物理原因出发,定义了相位共轭镜（PCM）的响应时间．建立起非即变相位共轭反馈条件下半导体激光器的外腔模型。以响应时间及频率失调为参变量,对其分岔及噪声等动态行为进行数值分析。结果表明,不考虑噪声影响时,增加相位共轭镜响应时间会使混沌带出现的次数和范围得到较大的抑制,当响应时间增大到1．5ns时,混沌带消失,半导体激光器保持稳定的单周期状态;考虑噪声影响后,随若响应时间的相对强度噪声（RIN）可减小几dB甚至十几dB,产生突变需要的反馈量也增大一个数量级以上,且其频谱的峰值向高频方向移动;另外,由于共轭反馈引起的频率失调低于半导体激光器激射频率3个数量级以上．它只对分岔特性有影响．对相对强度噪声的影响几乎为零。     

TM掺杂Ⅱ-Ⅳ-Ⅴ2黄铜矿半导体的电磁性质

利用自旋局域密度泛函的第一性原理对3d过渡金属(TM=V，Cr，Mn，Fe，Co和Ni)掺杂的Ⅱ-Ⅳ-Ⅴ2(CdGeP2和ZnGeP2)黄铜矿半导体的电磁性质进行系统计算，结果发现：V和Cr掺杂的CdGeP2和ZnGeP2将出现铁磁状态(FM)，Mn，Fe以及Co掺杂的CdGeB和ZnGeP2将出现反铁磁状态(AFM)，而Ni掺杂时，稀磁半导体(DMS)的磁性比较不稳定，其中Cr掺杂的CdGeP2和ZnGeP2将可能是具有较高居里温度Tc的DMS，当TM-3d电子的t2g态部分被填充时，其掺杂的DMS将出现FM状态；而当TM-3d电子的t2g态全满或者全空时，其掺杂的DMS将出现AFM状态，在(Cd，Mn)GeP，和(Zn，Mn)(GeP2中分别掺入电子和空穴载流子，可以发现载流子是否具有TM-3d电子的巡游特性是。DMS是否出现FM状态的主要原因。     

Research on characterization of frequency chirp in RSOA

Light chirp is a major issue in optical fiber links. This letter deals with precise characterizations of the frequency chirp parameters of reflective semiconductor optical amplifiers （RSOAs）. The RSOA chirp properties are represented by transient and adiabatic chirps, whose parameters are characterized utilizing a ratio between the phase and the amplitude modulation depths of the RSOA when modulated with sine waves. Utilizing a high-resolution optical spectrum analyzer, a RSOA linewidth enhancement factor a and an adiabatic factork are obtained experimentally, based on which the influence of chirp parameters on the transmission performance of non-return-to-zero （NRZ） signals can be analyzed.     

2 kW半导体激光加工光源

针对激光加工在金属材料焊接、熔覆、表面硬化等工业领域的应用,考虑到半导体激光器体积和重量小、效率高、免维护、成本低以及波长较短等特点,设计了功率达2 kW的半导体激光加工光源。在大通道工业水冷条件下,采用48只出射波长分别为808,880,938,976 nm的传导冷却半导体激光阵列作为发光单元,最终研制出了2 218 W高亮度光纤耦合模块。此高亮度模块可以实现柔性加工,直接应用于金属材料焊接、熔覆、表面合金化等工业领域,对于半导体激光器在工业领域的应用具有重要意义。     

稀磁半导体Zn1-xFexO纳米颗粒的光谱研究

利用水热法制备了Zn1-xFexO(x=0,0.01,0.05,0.10和0.20)纳米稀磁半导体材料。由X射线衍射图谱的结果表明,制备的Zn1-xFexO样品为纤锌矿结构,没有金属铁等第二相出现;高分辨透射电子显微镜的结果表明,形貌为分散性良好的纳米颗粒,晶格清晰;拉曼光谱结果表明(E2High)峰位向高频移动,半高宽宽化,峰强减弱;光致发光光谱结果表明,随着Fe离子的掺入,紫外峰向低能移动,光致发光光谱发生了猝灭现象;UV-Vis光谱可看出,光学带隙减小,发生了红移现象。这些结果表明Fe3+成功替代Zn2+进入到ZnO晶格。     

一种基于布拉格反射波导的表面等离子体激光光源（英文）

设计了一种基于布拉格反射波导的新型表面等离子体激光光源。这种光源结构简单,便于集成,可以在室温电泵浦的条件下工作,同时可以输出约毫瓦量级的表面等离子激光,相比于文献报道中纳米尺度的纳瓦级表面等离子体激光光源要高很多。该表面等离子体激光光源发射波长为808 nm,布拉格反射波导所提供的倾斜激光光线在我们设计的准Otto模型中可以直接耦合成为表面等离子体。     

Four distributed feedback laser array integrated with multimode-interference and semiconductor optical amplifier

Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4×1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demonstrated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio (SMSR) exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously.     

Oscillation of coercivity between positive and negative in MnxGe1-x：H ferromagnetic semiconductor films

Amorphous MnxGe1-x :H ferromagnetic semiconductor films prepared in mixed Ar with 20% H2 by magnetron cosputtering show global ferromagnetism with positive coercivity at low temperatures. With increasing temperature, the coercivity of MnxGe1-x :H films first changes from positive to negative, and then back to positive again, which was not found in the corresponding MnxGe1-x and other ferromagnetic semiconductors before. For Mn0.4Ge0.6 :H film, the inverted Hall loop is also observed at 30 K, which is consistent with the negative coercivity. The negative coercivity is explained by the antiferromagnetic exchange coupling between the H-rich ferromagnetic regions separated by the H-poor non-ferromagnetic spacers. Hydrogenation is a useful method to tune the magnetic properties of MnxGe1-x films for the application in spintronics.     

Lead zirconate titanate behaviors in an LDMOS

The behaviors of lead zirconate titanate (PZT) deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current-gate voltage (ID-VG) memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor (LDMOS). The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.     

785nm便携式光栅外腔可调谐半导体激光器的研制和输出特性

针对移频激发拉曼光谱测试系统的小型化需求,在Littrow结构中,采用商用的785nm大功率激光二极管作为增益器件,构建了一款便携式光栅外腔可调谐半导体激光器。该激光器通过采用一种新型的波长调谐方法,即以改变半导体增益器件相对于准直透镜的水平位置来实现波长的连续调谐,实现了尺寸为140mm×65mm×50mm的小型化结构设计。相比于传统的旋转衍射光栅改变光线在光栅上的入射角来实现波长调谐的方式,该方法有效地缩减了增益器件的平移距离,从而有利于便携式外腔激光器波长的快速宽带调谐。实验结果表明,该激光器具有较宽的波长调谐范围,在340~900mA注入电流下均可实现10nm以上的波长调谐,尤其在900mA大注入电流下,其波长调谐覆盖779.40~791.07nm,调谐范围可达11.67nm,且激射线宽小于0.2nm,单波长输出功率最高可达280mW,放大的自发辐射抑制比大于25dB,呈现出较优异的输出性能,满足移频激发拉曼光谱检测系统对光源的基本要求。此外,该激光器可采用一微型压电陶瓷驱动器来实现波长的电动调谐,实验获得了1.35nm的波长调谐范围,证实了所制785nm便携式光栅外腔可调谐半导体激光器适合作为便携式移频激发拉曼光谱检测系统的光源用于减除原始拉曼光谱中的荧光背景。