High-Temperature Continuous-Wave Operation of GaInAsN–GaAs Quantum-Dot Laser Diodes Beyond 1.3 μm

Internal laser parameters and characteristic temperature T₀ of a GaInAsN-GaAs quantum-dot (QD) laser emitting above 1350 nm were determined. Continuous-wave operation of GaInAsN-GaAs QD ridge waveguide laser diodes with an emission wavelength of 1355 nm at room temperature (RT) is reported for the first time. Low threshold currents of 16 mA are achieved at RT. Ground state laser emission is observed up to temperatures of 75degC with a resulting laser emission wavelength of 1395 nm.     

Random lasing in vertical ZnO nanorods

Random lasing with coherent feedback is detected in the array of vertical ZnO nanorods synthesized on a Si(100) substrate. Under high-intensity optical pumping at the wavelength of 337.1 nm at room temperature, several narrow laser peaks with the width of 0.1 nm are observed in the wavelength region around 392 nm. The laser radiation is emitted in a direction orthogonal to the axis of the nanorods. Study of the behavior of the laser spectrum with the excited area shows good agreement of the data with the theory of random lasers. The mechanism of laser emission is related to the formation of closed paths of light due to multiple coherent scattering at the vertically oriented ZnO nanorods.     

Investigation of laser-mode anticompetition in semiconductor lasers

Influential factors of laser-mode anticompetition are investigated in dual-wavelength semiconductor laser. Experiment shows that with increasing wavelength, separation, or decreasing initial power of the long-wavelength mode (LWM), the slope of the anticompetition curve and the maximum power increment of the LWM increase. Under fixed wavelength separation, anticompetition can exist only when the power of the short-wavelength mode (SWM) is below a certain level. In addition, the wavelength position has an effect on anticompetition. Different injection current also results in different behaviors of anticompetition. Anticompetition can only be observed with varying the power of the SWM.     

单反馈He-Ne激光器混沌激光产生的理论及实验研究

基于外光反馈机制,利用He-Ne激光器(中心波长为632.8nm)进行了混沌激光产生的理论及实验研究。在固定抽运电流和外腔长度的情况下,研究不同反馈系数对He-Ne激光器输出特性的影响。理论及实验结果表明:He-Ne激光器在单反馈下随着反馈系数的增大可通过周期态进入混沌。     

InAs-InAlGaAs quantum dot DFB lasers based on InP [001]

The InAs-InAlGaAs quantum dot (QD) lasers with the InAlGaAs-InAlAs material system were fabricated on distributed feedback (DFB) grating structures on InP [001]. The single-mode operation of InAs-InAlGaAs QD DFB lasers in continuous-wave mode was successfully achieved at the emission wavelength of 1.564 /spl mu/m at room temperature. This is the first observation on the InP-based QD lasers operating around the emission wavelength window of 1.55 /spl mu/m. The threshold current density of the InAs-InAlGaAs QD DFB laser with a cavity length of 1 mm and a ridge width of 3 /spl mu/m, in which one of the cleaved facets was coated with 95% high-reflection, was 1.23 kA/cm/sup 2/ (176 A/cm/sup 2/ for single QD layer). The sidemode suppression ratio value of the QD DFB laser was as high as 42 dB at the driving current of 100 mA.     

Temperature insensitive 1.3 /spl mu/InGaAs=GaAs quantum dot distributed feedback lasers for 10 Gbit=s transmission over 21km

Long wavelength monomode InGaAs/GaAs quantum dot (QD) distributed feedback (DFB) lasers with emission wavelength around 1325 nm are presented. Threshold currents below 19 mA for operating temperatures up to 70degC and output powers of 10 mW at 25degC (6 mW at 70degC) are observed. Error-free 10 Gbit/s transmission over 21 km fibre with an extinction ratio of 8.5 dB at room temperature (5.1 dB at 70degC) is demonstrated. The low threshold, low temperature sensitivity and high modulation speed were realised using complex coupled DFB lasers with ten stacks of self-organised MBE-grown QD layers and p-type modulation doping     

激光二极管阵列的窄线宽、可调谐输出

外腔反馈的激光二极管阵列(LDA)可获得窄线宽、可调谐的光谱输出。外腔由快轴准直镜、准直光学系统和闪耀光栅组成。由于阵列中各发光单元的排列弯曲导致不同波长的光原路返回,引起谱线展宽,在输出光路中加入光谱滤波器,使激光二极管阵列的线宽进一步窄化。这样,激光二极管阵列的输出光谱由自由运转时的2 nm压缩到0.12 nm,在恒定温度23℃时,实现了激光在806～818 nm的调谐,调谐范围达12 nm。     

Polarization switching of an er :yb :cr: phosphate glass microchip laser

We show that the light of a commercially available Er:Yb:Cr.-phosphate glass microchip laser end-pumped at 977 nm by an InGaAs laser diode can be switched between two linear polarization eigenstates when it is submitted to a polarized optical feedback. The flip occurs when the feedback phase is scanned by the external cavity length. In our experiments the laser diode light is confined to a fiber which is single-mode at pumping wavelength and the microchip laser operates in a single-longitudinal-and transverse mode. The microchip laser exhibits a self-pulsing behavior.     

半导体激光器的原子法拉第反常色散光学滤波器光反馈稳频

为提高半导体激光器的频率稳定性，利用原子法拉第反常色散光学滤波器（FADOF）超窄带的选频透射特性，将其置于半导体激光器的外腔中作选频元件，采用光反馈的方法，使得透射率低的激光频率分量被抑制，透射率高的激光频率分量被加强，有效地实现了光反馈激光稳频。利用Cs原子法拉第反常色散光学滤波器工作于D2线852nm的4峰窄带透射状态。通过调节半导体激光器的温度和电流，调谐半导体激光器的输出波长，将激光器锁定在任何一个透射峰上，用26％的光反馈量，使稳频后的激光频率长期稳定性保持在75MHz／2h以内，而且采用这种稳频方法的输出激光中心波长一直稳定在频率基准上，没有单方向漂移。同时，还实现了Cs原子法拉第反常色散光学滤波器稳频半导体激光器结构的一体化，使其具有实用性。     

双波长光纤光栅外腔半导体激光器中波长转换

提出了基于双波长光纤光栅外腔半导体激光器增益饱和效应的全光波长转换方案，特点是可将输入信号同时转换到激光器的2个波长上。在静态波长转换实验中，观察到了1554.8nm输入信号对激光器1531.5nm与1549.4nm波长输出功率的增益饱和作用。表明可实现输入信号到激光器的两个波长的同时转换。     

Multi-Data-Rate System Performance of a 40-GHz All-Optical Clock Recovery Based on a Quantum-Dot Fabry–PÉrot Laser

Bit-error-rate assessment of a multi-rate all-optical clock recovery (OCR) based on a narrow linewidth mode-locked quantum-dot (QD) Fabry-Perot laser is presented in this letter. OCR has been achieved without external feedback. We use a QD Fabry-Perot semiconductor laser designed for 40-GHz clock extraction. We then present OCR performance with 40-, 80-, and 160-Gb/s input data signal and demonstrate that clock recovery has been obtained thanks to subharmonic locking process. Results are presented through penalty measurement using an original characterization based on recovered clock remodulation with electrical data from the transmitter. This technique allows us to evaluate the quality of the recovered clock.     

Room-temperature singlemode continuous-wave operation of distributed feedback GaInNAs laser diodes at 1.5 μm

Room-temperature continuous-wave operation of distributed feedback GalnNAs quantum well laser diodes on GaAs in the 1.5 mum wavelength range is demonstrated for the first time. Singlemode emission with a sidemode suppression ratio of more than 45 dB is obtained at 1486 nm with a threshold current of 44 mA and an external efficiency of 0.06 W/A.     

外腔半导体激光器设计与高次谐波稳频

研究了利特罗(Littrow)结构外腔半导体激光器的结构参量对激光连续可调范围的影响。给出了反射镜转轴等处的机械加工误差对激光波长连续可调范围所造成的影响的数值计算结果。介绍了半导体激光器外腔结构设计的具体细节要点。利用该设计制作的外腔只需要配合商用半导体激光管便可以得到优质的780nm激光输出,经测量其线宽小于1MHz,连续可调谐范围大于3GHz。利用腔外Rb饱和吸收谱的三、五次谐波稳频方法对半导体激光器进行了稳频。其中提出了优化激光频率短期稳定度的方法,并对调制深度的选择给出了详细的理论解释。根据该优化方法设计出稳频系统对半导体激光器进行稳频,得到了稳定度达到10-12量级的半导体激光输出。     

用光纤光栅作外反馈的可调谐外腔半导体激光器

制作了一种以光纤光栅作为外反馈的半导体激光器。光纤光栅用紫外曝光法制作 ,反射率为 5 0 %。器件在5 0mA注入电流时 ,出纤功率高于 1mW ,主边模抑制比为 42dB。使用对光纤光栅施加应变和改变光栅温度的方法实现了输出激光波长的调谐 ,利用施加应变方法得到了 2nm范围的输出波长变化。     

连续工作的体布拉格光栅外腔半导体激光器的温度特性

对体布拉格光栅(VBG)作为波长选择元件的外腔半导体激光器的波长锁定进行了实验研究,报道了连续运转输出功率达43.5 W的半导体激光器阵列的体布拉格光栅波长锁定实验结果,给出了不同热沉温度下的稳定的波长锁定结果,说明采用体布拉格光栅外腔将减小半导体激光器的温控压力。实验中发现,随着注入电流的增大,输出激光功率逐渐增强,锁定的激射波长向长波长方向偏移。在输出功率为34.5 W时,波长红移约0.56 nm。这一移动与实验测量的体布拉格光栅的温度特性相吻合。连续和高占空比运行、高输出功率情况下,在器件的设计和使用时应该考虑这一效应。     

Widely Tunable GaSb-Based External Cavity Diode Laser Emitting Around 2.3$mu$m

We report on a widely tunable external cavity GaSb-based diode laser (ECL) in Littrow-configuration. The low (44$^circ$full-width at half-maximum) fast axis beam divergence of the quantum-well diode laser employed allowed an efficient coupling to the external cavity, which resulted in a wide tuning range of 177 nm around the central emission wavelength of 2.30$muhbox m$. The maximum output power of the fiber coupled ECL system varied only moderately between 16.5 mW at 2.23$muhbox m$and 9 mW at the long-wavelength limit at 2.39$muhbox m$.     

Sequential TE/TM polarization emission from a tunable externalcavity diode laser

A tunable external cavity diode laser that emits in a closely spaced sequence of alternating TE and TM wavelength intervals in the range between 1256 and 1282 nm is reported. In each interval, stable single longitudinal mode TE and then TM emission occurs that can be tuned in wavelength. Two consecutive intervals are separated by a wavelength region where emission instabilities are observed. The wavelength spacing between two successive intervals belonging to the same polarization state corresponds to the mode spacing of the solitary diode laser. As the laser is tuned beyond 1282 nm and up to 1316 nm, the emitted radiation is only TM polarized. The above-mentioned phenomena are based on the composite cavity gain modulation with the wavelength, and on the comparable losses of the system for the TE and TM polarization     

ZnO近紫外波长纳米激光器的研究

随着纳米科技的兴起,纳米激光的研究成为了又一个新的重要课题.ZnO纳米微晶有两种结构可以产生随机激光,一是六角柱形蜂窝状微晶结构,二是颗粒粉末状结构,产生的近紫外激光波长是387.5 nm,光泵浦阈值是50 kW/cm2.采用气相输运的催化外延晶体生长过程来制备ZnO纳米线阵列构成的光致纳米激光器,激光波长383 nm,线宽仅为0.3 nm,光泵浦阈值是40 kW/cm2.     

激光诱导碘荧光(LIIF)强度与激发激光波长的关系

理论上简要地分析了在可见光波段碘荧光强度与激发激光波长的关系 ,并用波长为 5 32nm半导体倍频Nd :YAG激光、波长为 5 14 .5nm、5 0 1.7nm、4 96 .5nm和 4 88nm的氩离子激光激发碘分子 ,通过对获得的荧光信号分析得出 ,五种波长的激光均可诱导出碘荧光。对相同的激光功率 ,波长为 5 32nm的倍频Nd :YAG诱导出的碘荧光信号比波长为 5 14 .5nm的氩离子激光强 ,两种激光均可作为碘气体的激发激光。其它三种波长激光诱导出碘荧光强度弱 ,在激发激光传输方向衰减明显 ,不适合作为碘荧光的激发激光。