耦合垂直腔面发射激光器输出波长的理论研究

阈值载流子浓度及输出波长是研究耦合垂直腔面发射激光器的一个重要方面.本文利用边界条件.结合激光器中间DBRS层的耦合传输矩阵.推导出了双波长激射时的阈值载流子浓度,以及中间DBR层数对输出波长的影响.     

LD条宽对激射波长影响的研究

报道了LD激射波长会随条宽发生明显变化.对有相同外延生长结构和制作工艺、不同条宽的960 nm LD的激射波长进行研究发现,条宽为130、100、75和50 μm的器件的激射波长依次变短.进一步分析认为,这是因为条宽变窄导致器件阈值电流密度、阈值载流子密度变大造成的.根据GaAs材料在不同注入载流子密度下的增益谱及器件条宽变化对阈值载流子密度的影响,可以对实验现象进行合理的解释,从而在器件研制中可通过改变条宽对器件的激射波长在一定范围内进行调节.     

耦合垂直腔面发射激光器的耦合特性理论分析

确定耦合垂直腔面发射激光器中两腔光子之间的耦合关系是分析其工作特性的基础.本文利用边界条件,结合激光器中间DBRs层的耦合传输矩阵,推导出了不同激射波长工作时,两腔内光场应满足的方程,由此得到两腔光子之间的耦合因子,研究了腔内载流子浓度对耦合因子的影响.     

耦合垂直腔面发射激光器的阈值及输出特性

针对耦合垂直腔面发射激光器,利用边界条件,结合激光器的中间DBR层的耦合传输矩阵,推导出了不同激射波长工作时,两腔内光场应满足的方程,由此得到两腔光子之间的耦合因子,然后结合稳态载流子速率方程,按照激射波长,得出了器件的四种工作状态,并详细地讨论了顶腔和底腔注入电流对器件输出特性的影响.     

面向长距离通讯1550 nm垂直腔面发射激光器的研究

采用InP基衬底设计并制备了1550 nm垂直腔面发射激光器。采用混合镜面布拉格发射镜,其中顶部采用4.5对硅和二氧化硅的介电布拉格反射镜,同时采用隧道结的方式降低p层载流子吸收。制备出阈值电流在20 mA,室温直流下输出光功率为7 μW,激射波长为1554 nm,激射谱半高宽为3 nm的垂直腔面发射激光器。     

基于激光瞬态特性的内腔气体浓度光纤传感器

报道了一种基于掺铒光纤激光器瞬态特性的内腔吸收式气体浓度传感器.介绍了掺铒光纤激光器内腔吸收谱的基本原理,以及激光激射延迟时间与气体浓度的关系.用光纤环全反镜和光纤Bragg光栅构成F-P线形腔,通过调节光栅的反射波长,使激光激射波长落在乙炔的一个较强的吸收峰1532.83 nm上.通过测量激光激射延迟时间可以获得气体的浓度.实验证实了方案的可行性,该装置的灵敏度可以达到10×10~(-6).     

垂直外腔面发射半导体激光器的双波长调控研究

报道了一种结构紧凑的垂直外腔面发射激光器（Vertical-External-Cavity Surface-Emitting Laser,VECSEL）及其双波长调控。通过调控泵浦光功率,实现了VECSEL输出的两个激光波长之间的相互转换,双波长的间隔接近50 nm。VECSEL的输出功率曲线呈现明显的两次翻转,翻转点对应了激射波长的转换。这是由于泵浦功率变化改变了增益芯片内部的温度,进而通过热调谐使得发光区增益峰值被调谐到腔模的不同位置。在0℃时,每个激射波长的最大输出功率都在1.5 W以上。随着泵浦功率的改变,激射波长可以在950 nm和1000 nm之间切换,同时还可以在1.5 W以上的功率水平下实现双波长同时激射。这种可切换波长及双波长同时激射的VECSEL器件在光调制、差频等领域有较大应用潜力。     

面向长距离通讯1550 nm垂直腔面发射激光器的研究（英文）

采用InP基衬底设计并制备了1550 nm垂直腔面发射激光器。采用混合镜面布拉格发射镜,其中顶部采用4.5对硅和二氧化硅的介电布拉格反射镜,同时采用隧道结的方式降低p层载流子吸收。制备出阈值电流在20 mA,室温直流下输出光功率为7μW,激射波长为1554 nm,激射谱半高宽为3 nm的垂直腔面发射激光器。     

广义两段式半导体激光器的特性研究

利用由射线法导出的两段式半导体激光器(2SLD)的端面输出谱的表达式,研究了两电极半导体激光器(2ELD)和外腔式半导体激光器(ECLD).结果表明;2ELD的振荡波长并非始终都与腔的共振波长相同;在ECLD上实现准连续调谐的关键是使激光器能被调谐在二极管的反共振波长处振荡,因此,我们求得了ECLD实现反共振激射的阈值载流子数密度以及对界面反射率的要求的表达式。     

窄线宽多波长掺铒光纤激光器

在掺铒光纤线型的单模光纤腔中接续一段多模光纤 ,依靠多模光纤中导模的空间模式跳动与激光谐振腔中的偏振烧孔共同作用 ,实现了窄线宽多波长的同时激射。激射波长的 3d B线宽约为 0 .0 9nm ,波长间隔为 0 .6 8nm。     

Wavelength aging analysis of DBR lasers using tuning section IMfrequency response measurements

Systematic IM frequency response measurements have been performed on the tuning section of distributed Bragg reflector lasers aged at 60°C and 120°C. The wavelength drift varies exponentially with aging time as well as carrier lifetime of the tuning section. The carrier lifetime increases with time indicating a wavelength drift mainly due to leakage current increase at high carrier density injection     

Carrier-induced lasing wavelength shift for quantum well laser diodes

Lasing wavelength was analyzed for quantum well laser diodes (QW-LD's) considering both the bandgap shrinkage effect and the band-filling effect. The bandgap shrinkage effect was calculated by the local density functional method, treating both electron and hole distribution self-consistently. Assuming nok-selection rule, the band-filling effect is larger than the bandgap shrinkage effect when the carrier density is high. The lasing wavelength shifts to the short side as the threshold carrier density increases. QW-LD's with a large threshold carrier density lase at very short wavelength corresponding to the transition between the second sublevel. However, this wavelength is still longer than that expected because of the bandgap shrinkage effect.     

Experimental observation of asymmetric detuning characteristics in semiconductor laser injection locking

The effects of refractive index dependence on the active region carrier density in semiconductor laser injection locking have been examined experimentally. Strong asymmetry has been observed in the relation between locked longitudinal mode intensity and the difference between an original longitudinal mode wavelength and the injecting light wavelength.     

垂直腔半导体光放大器调谐输出特性分析

为了分析垂直腔半导体光放大器的调谐输出特性,考虑到有源腔有效折射率和载流子浓度之间的关系,并结合载流子速率方程,采用建立腔内平均光子数与输入信号光功率之间的关系的研究方法,对垂直腔半导体光放大器的调谐输出特性进行了理论分析和数值仿真.结果表明,在一定的输入光功率和波长条件下,可以观察到双稳现象;双稳环的宽度随着输入光功...     

调制激光激发PN结少数载流子分布及频域响应特性研究

为建立载流子辐射检测Si基太阳能电池的理论模 型,基于太阳能电池非线性耦合方程对调制激光激 励下Si太阳能电池过剩少数载流子的空间分布与频率响应特性进行了仿真分析,对基区、耗 尽层和发射区 的载流子分布与超带宽调制激光的波长、功率密度和调制频率的关系进行了定量研究,通过 仿真结果选定 调制激光的最佳参数范围,进行了载流子辐射频域响应和载流子寿命对频域响应影响的仿 真计算。仿真 结果表明,过剩载流子浓度随扫描频率的增加呈现非线性特征,所用仿真模型对激发参数和 输运参数有较高 的灵敏度。最后对Si基太阳能电池片进行了扫频验证实验,实验结果与仿真结果符合良好, 表明所使用的 仿真方法能够预测载流子辐射技术的检测结果,可用于对调制载流子辐射检测技术仿真和结 果预测。     

Numerical analysis of static wavelength shift for DFB lasers with longitudinal mode spatial hole burning

The static wavelength shift induced by longitudinal mode spatial hole burning is analyzed numerically for lambda /4-shifted DFB lasers. The effective Bragg wavelength at each bias level is introduced to clarify the contribution of nonuniformity in carrier density distribution to the lasing wavelength shift. It is shown that the wavelength shift is caused by two separate factors: by the position-dependent deviation and by the average value in the exact N/sub eq/ distribution. The former factor induces both red- and blue-shifted tuning due to the nonuniformity itself in carried density distribution, while the latter results in blue-shifted tuning due to the increase in modal gain.<>     

Effect of different loss mechanisms in SiGeSn based mid-infrared laser

We have analyzed the mid-infrared SiGeSn based Barrier-Well-Barrier Heterostracture and calculated the transparency carrier density and corresponding current density for the structure. The effects of different loss mechanisms like free carrier absorption, spontaneous recombination and Auger recombination processes on the transparency current density have been examined. It is shown that, the transparency current density increases significantly with the injected carrier density. Different scattering processes like acoustic phonon scattering and intervalley optical phonon scattering are taken into consideration for this analysis of free carrier absorption mechanisms.

     

Low-threshold 1.5 μm compressive-strained multiple- andsingle-quantum-well lasers

Design considerations for low-threshold 1.5-μm lasers using compressive-strained quantum wells are discussed. Parameters include transparency current density, maximum modal gain, bandgap wavelength, and carrier confinement. The optical confinement for a thin quantum well in the separate-confinement heterostructure (SCH) and the step graded-index separate-confinement heterostructure (GRINSCH) are analyzed and compared. 1.5-μm compressive-strained multiple- and single-quantum-well lasers have been fabricated and characterized. As a result of the compressive strain, the threshold current density is loss limited instead of transparency limited. By the use of the step graded-index separate-confinement heterostructure to reduce the waveguide loss, a low threshold current density of 319 A/cm² was measured on compressive-strained single-quantum-well broad-area lasers with a 27 μ oxide stripe width     

Effect of different type intermediate layers on band structure and gain of Ga/sub 1-x/In/sub x/N/sub y/As/sub 1-y/-GaAs quantum well lasers

Based on the band-anticrossing model, the effect of the strain-compensated layer and the strain-mediated layer on the band structure, the gain, and the differential gain of GaInNAs-GaAs quantum well lasers have been investigated. Different band-filling mechanisms have been illustrated. Compared to the GaInNAs-GaAs single quantum well with the same wavelength, the introduction of the strain-compensated layer and the strain-mediated layer increases the transparency carrier density. However, these multilayer structures help to suppress the degradation of the differential gain.     

Analysis of gain and saturation characteristics of a semiconductorlaser optical amplifier using transfer matrices

The transfer matrix method (TMM) has been applied to analyze the gain and saturation characteristics of semiconductor laser optical amplifiers. This method approximates the amplifier cavity by dividing it into M discrete subsections, and TMM has been applied to analyze the stepwise longitudinal field distribution at each subsection along the amplifier cavity. By incorporating also the carrier rate equations into the analysis, it has been shown that the approximation can accurately describe the carrier density and longitudinal field distribution along the amplifier cavity if M is sufficiently large (i.e., the size of each subsection is about an order of magnitude of one wavelength of the input signal). By assuming that the amplifier is biased below oscillation threshold such that the contribution of spontaneous emissions to the gain characteristics can be neglected, we have shown that our proposed method yields a fast and efficient algorithm in analyzing the gain and saturation characteristics of laser amplifiers. We have compared the results produced by our method to those analyzed using the average photon density (AVPD) approximation technique, as well as to experimental results on a 1.5-μm buried heterostructure semiconductor laser amplifier