一种分布反馈注入放大半导体激光器的研制

研制了一种小型大功率半导体激光器系统。将分布反馈半导体激光器输出的小功率光注入到锥形芯片放大器后实现功率放大,得到功率大于700 mW,波长连续可调谐范围大于1 nm的输出激光。该激光器系统不但结构紧凑、输出功率稳定,而且操作方便。该系统可在激光冷却与囚禁、超冷量子气体、量子信息、原子频标及相关空间实验研究中得到应用。     

分布反馈光纤激光器自放大特性实验研究

通过相位掩膜板移动法,制作了非对称相移结构分 布反馈光纤激光器(DFB-FL)。为了获得更高的激光功率,利 用同样长度的掺铒光纤(EDF),分别采用同向泵浦和反向泵浦结构方式进行了窄线宽激光信 号的自放大实验,结 果表明,两种自放大结构的DFB-FL均可充分利用泵浦光功率,在保证激 光线宽展宽有限的前 提下,实现了激光信号至少23dB的功率放大。同时,实验结果对比 说明,同向泵浦放大结构更有利于保 持原激光信号的噪声特性。这为较大输出功率的DFB-FL提供了一种简单 可行的方案。     

单环掺铒光纤激光器光延迟反馈的混沌控制

为了找到更加简单稳定激光系统的混沌化方法,采用光延迟反馈方法对单环掺铒光纤激光器特性进行了数值仿真,得到了各种周期现象而且产生了混沌现象。结果表明,利用单模单环掺铒光纤激光器,在附加光延迟反馈环路的方法下可以实现混沌控制。这一结果对应用于保密通信的混沌化简化具有重要意义。     

采用移频反馈的SOA多波长光纤环形激光器

文章报道了一种基于移频反馈的半导体光放大器(SOA)多波长光纤环形激光器,其环腔内插入声光调制器作为移频器,用自制的光纤马赫-曾德干涉仪进行梳状滤波,在输出光谱1.5 dB带宽为21.7 nm范围内,获得了间隔50 GHz的54个稳定的多波长连续光激射,消光比为28 dB.该激光器具有工作稳定性好、输出光谱宽和不同波长功率平坦度高的优点.实验证明,移频反馈技术能够实现激光器不同起振波长间的增益均衡,使输出光谱带宽增大21.7%.     

电流反馈放大器及其应用

介绍了电流反馈放大器及由它构成的ＲＣ正弦振荡器，滤波器和电感仿真与频变负阻仿真电路。分析了ＣＦＡ的寄生电阻玫电容对ＲＣ振荡器性能的影响，得到了忽略寄生电阻与电容的条件下。提出了ＣＦＡ构成的各类基本运算电路。     

分布反馈和螺旋反馈激光器的最新耦合波理论

给出了无相位匹配和有相位匹配分布反馈激光器以及螺旋反馈激光器的统一解析耦合波理论。该理论限于折射率、波导截面或增益为弱简谐周期调制或螺旋调制。导出了激光模的色散关系、共振频率和阈值增益的近似解析表达式。     

分布反馈染料激光器实验研究

对一种能够产生亚皮秒(0．5ps)超短脉冲的宽波段可调谐分布反馈染料激光器的工作原理进行了分析并给出了具体的实验结果。结果表明该系统通过简单地更换光学元件就可以同时实现脉冲宽度可调。另外,给出了一种获得单模激光输出分布反馈染料激光器的调节方法。     

1550 nm GaInNAsSb distributed feedback laser diodes on GaAs

Single mode laser diodes on GaAs substrates were developed using GalnNAsSb double quantum well active regions grown by molecular beam epitaxy. The distributed feedback devices were fabricated using a regrowth-free process in which lateral Cr gratings were deposited adjacent to a dry-etched narrow ridge waveguide. In continuous- wave (CW) operation the devices exhibit a lasing wavelength of 1550 nm at 10degC with a very high sidemode suppression ratio of > 50 dB throughout most of the operational range, and output power up to 15 mW.     

Unidirectional laterally gain-coupled distributed feedback ring laser diodes

The authors report the development of laterally gain-coupled ring lasers that exhibit uni-directional and singlemode operation. Counterpropagating modes in the ring are suppressed such that 83% of the light output comes from only one propagation direction. The mode stability of the ring laser is significantly improved through the introduction of a gain-coupled distributed feedback mechanism.     

Analysis of the spectral linewidth of distributed feedback laser diodes

The spectral linewidth of distributed feedback (DFB) laser diodes is theoretically studied. Numerical calculation shows that DFB lasers with long cavity lengths and large coupling coefficients have very narrow spectral linewidth less than 1 MHz, The effects of the phase shift and mirror facets on the spectral characteristics of DFB lasers are also analyzed, It is shown that the phase-shifter further narrows the spectral linewidth of DFB lasers. Its numerical result and physical meaning are also shown.     

Analysis of the spectral linewidth of distributed feedback laser diodes

The spectral linewidth of DFB laser diodes is analysed. DFB lasers with long cavities are shown to have very narrow spectral linewidth, and it is further narrowed if a phase shift is introduced at the centre of the cavities.     

Spectral characteristics of distributed feedback laser diodes withdistributed coupling coefficient

A comprehensive investigation of the spectral characteristics of distributed feedback (DPB) laser diodes (LD's) with a distributed coupling coefficient (DCC) is presented. With a proper selection of both the coupling ratio (r) and a corrugation position (CP), the performance of the DCC laser structure is enhanced with an improved single-mode stability as well as a uniform field distribution. In the analysis, the above threshold characteristics and the influence of non-lasing side modes have been investigated using the transfer matrix method (TMM). Based on a DCC laser structure with r=1/3 and CP=0.46, a normalized gain margin (ΔαL)=0.81 and a side mode suppression ratio (SMSR) of 45 dB have been achieved for a DCC LD at biasing current of 4I_th . The introduction of the DCC laser structure opens a new way of stabilizing the single-mode oscillation in DFB LD's     

Degradation analysis in asymmetric sampled grating distributed feedback laser diodes

This paper presents the experimental observation of the degradation in asymmetric sampled grating DFB lasers by the accelerated life tests. Two degradation phenomena related to the electrical characteristics of LDs are observed during the tests. The first degradation phenomenon by increasing the reverse current is considered as a formation of leakage current path enough to prevent lasing operation in lateral blocking layer near active region of lasers. The second degradation phenomenon by decreasing the forward current is considered as activation of non-radiative Auger recombination process by thermal energy. It is also experimentally observed that the second degradation phenomenon is recovered after remained in room temperature with no electrical stress. Therefore, the criteria for LD reliability can be determined by observing the degradation of the reverse current–voltage characteristics.     

GaInNAs-based distributed feedback laser diodes emitting at 1.5 /spl mu/m

For the first time, GaAs-based 1.5 /spl mu/m singlemode emission has been realised utilising GaInNAs active-layer material and lateral distributed feedback. The double quantum well separate confinement laser structure was grown by plasma-assisted molecular beam epitaxy. A threshold current of 240 mA and an external efficiency of 0.11 W/A could be demonstrated with a sidemode suppression ratio of better than 26 dB in pulsed operation. Singlemode emission up to 1506.5 nm has been realised.     

Transverse mode control in a distributed feedback semiconductor laser

Transverse modes in a distributed feedback semiconductor laser are discussed. A scheme for discriminating these modes is suggested.     

Tunable twin-guide distributed feedback laser diodes with over 9 nm continuous electro-optic tuning range

Tunable twin-guide laser diodes at 1.55 /spl mu/m with a record electro-optic tuning range are presented. Employing an optimised device design, continuous tuning ranges of 9.3 and 11.0 nm are achieved in continuous-wave (CW) and pulsed operation, respectively. In CW operation, the output power of 300 /spl mu/m-long devices remains above 1 mW throughout the whole tuning range.     

Liquid-phase epitaxy grown PbSnTe distributed feedback laser diodes with broad continuous single-mode tuning range

Distributed feedback (DFB) pulsed laser operation has been demonstrated in stripe geometry Pb1-xSnxTe double-heterostructures grown by liquid-phase epitaxy. The grating structure of 0.79 μm periodicity operates in first order near 780cm^-1(12.8 μm) and was fabricated prior to the liquid-phase epitaxial growth using holographic exposure techniques. These DFB lasers had moderate thresholds, 3.6 kA/cm², and the output power versus current curves exhibited a sharp turn-on free of kinks. Clean, single-mode emission spectra, continuously tunable over a range in excess of 20 cm^-1, centered about 780 cm^-1(12.8 μm), and at an average rate of 1.2 cm^-1. K^-1from 9 to 26 K, were observed. While weaker modes could at times be seen in the spectrum, substantially single-mode operation was obtained over the entire operating range and to over 10 times threshold. These observations have been shown to be in good agreement with published lead-salt parameter values and DFB theory, and significantly increase the attractiveness of the DFB structure for tunable lead-salt laser diodes.