InGaAsP/InP buried crescent laser diode emitting at 1.3 µm wavelength

The fabrication procedure, designing of an active region and a p-n-p-n current blocking structure, characteristics and the aging results of an InGaAsP/InP buried crescent (BC) laser diode are described. The BC laser diodes exhibit high laser performances, such as a low-threshold current, a fundamental transverse mode oscillation with linear light output-current characteristics. CW operation at as high as 100°C is achieved with a junction up configuration as a result of the improvement in the current blocking structure. A stable CW operation at 80°C has been realized with a constant optical output power of 5 mW.     

All-selective MOVPE-grown 1.3-μm strained multi-quantum-wellburied-heterostructure laser diodes

Strained InGaAsP multi-quantum-well (MQW) double-channel planar-buried-hetero (DC-PBH) laser diodes (LDs) were fabricated by selective metalorganic-vapor-phase epitaxy (MOVPE). In the laser fabrication process, both the strained MQW active layer and current blocking structure were directly formed by selective MOVPE without any semiconductor etching process. The LDs are called all-selective MOVPE-grown BH LDs. The laser fabrication process can achieve both a precisely controlled gain waveguide structure and an excellent current blocking configuration, realizing the optimized DC-PBH structure. These aspects are essential to the high-performance and low-cost LD, which is strongly demanded for optical access network systems or fiber-to-the-home networks. This paper will show the excellent high-temperature characteristics for 1.3-μm Fabry-Perot LDs which have a record threshold current of 18 mA with a low-operation current of 56 mA for 10 mW, and 74 mA for 15 mW at 100°C with extremely high uniformity. Furthermore, reliable long-term operation at high temperature (85°C) and high-output power of 15 mW has been demonstrated for the first time     

A 0.2 W CW laser with buried twin-ridge substrate structure

An extremely high output power has been obtained with a new structure laser named the buried twin-ridge substrate (BTRS) laser. The very thin active layer formed on a ridged substrate permitted high power output increasing the catastrophic damage level. The buried stripe formed with a blocking layer remarkably improved the current confinement lowering the threshold current. A multilayer coating technique was applied to both facets to increase the front facet output. Fundamental transverse mode is achieved at more than 100 mW in CW with an uncoated laser while the maximum output power attained is as high as 200 mW in CW operation with a multicoated laser.     

Very low threshold current density room temperature continuous-wavelasing from a single-layer InAs quantum-dot laser

Continuous-wave (CW) lasing operation with a very low threshold current density (J_th=32.5 A/cm²) has been achieved at room temperature by a ridge waveguide quantum-dot (QD) laser containing a single InAs QD layer embedded within a strained InGaAs quantum well (dot-in-well, or DWELL structure). Lasing proceeds via the QD ground state with an emission wavelength of 1.25 μm when the cavity length is longer than 4.2 mm. For a 5-mm long QD laser, CW lasing has been achieved at temperatures as high as 40°C, with a characteristic temperature T₀ of 41 K near room temperature. Lasers with a 20 μm stripe width have a differential slope efficiency of 32% and peak output power of >10 mW per facet (uncoated)     

Very-low-threshold, highly efficient, and low-chirp 1.55-/spl mu/m complex-coupled DFB lasers with a current-blocking grating

Low-threshold current DFB lasers have been fabricated based on a complex-coupled structure with a current blocking grating. A threshold current as low as 5 mA was obtained, which enabled high temperature operation up to 105/spl deg/C. Asymmetric facet coatings were applied to obtain a high efficiency of 0.3 W/A. The strained InGaAsP MQW active region and the antiphase coupling has resulted in a low modulation chirping. By direct modulation of the device at 2.488 Gb/s and using optical amplifiers, we have demonstrated digital transmission over a 235 km-long standard single-mode fiber with a power penalty of 1.55 dB.     

1.48-μm-wavelength ASM-DC-PBH LDs with extremely uniform lasingcharacteristics

High-power 1.48-μm erbium-doped fiber amplifier pumping InGaAsP MQW laser diodes (LDs) have been investigated using all selective metal-organic vapor phase epitaxy grown (ASM) fabrication method. The method provided a precise dimension control of multiquantum-well active layers and current blocking layers, resulting in excellent current blocking characteristics and extremely uniform lasing characteristics even at high injection current. The average light output power of 262 mW at 1 A with a standard deviation of as small as 1.4 mW for 20 consecutive LDs has been achieved     

高功率980nm非对称宽波导半导体激光器设计

设计了980nm非对称宽波导InGaAs/InGaAsP量子阱激光器,并在结构中插入电流阻挡层,有效地阻止载流子的泄露。用LASTIP软件对980nm非对称宽波导量子阱激光器进行理论模拟,与传统的980nm对称宽波导量子阱激光器相比,非对称宽波导量子阱激光器波导和量子阱之间有更小的能带差,非对称宽波导结构具有更低的阈值电流,更高的斜效率以及更低的阻抗,所以带有电流阻挡层的980nm非对称宽波导InGaAs/InGaAsP量子阱激光器有更高的光电转换效率和输出功率。     

High-power continuous-wave quantum cascade lasers

High-power continuous-wave (CW) laser action is reported for a GaInAs-AlInAs quantum cascade structure operating in the mid-infrared (λ≃5 μm). Gain optimization and reduced heating effects have been achieved by employing a modulation-doped funnel injector with a three-well vertical-transition active region and by adopting InP as the waveguide cladding material to improve thermal dissipation and lateral conductance. A CW optical power as high as 0.7 W per facet has been obtained at 20 K with a slope efficiency of 582 mW/A, which corresponds to a value of the differential quantum efficiency η_d=4.78 much larger than unity, proving that each electron injected above threshold contributes to the optical field a number of photons equal to the number of periods in the structure. The lasers have been operated CW up to 110 K and more than 200 mW per facet have still been measured at liquid nitrogen temperature. The high overall performance of the lasers is also attested by the large “wall plug” efficiency, which, for the best device, has been computed to be more than 8.5% at 20 K. The spectral analysis has shown finally that the emission is single-mode for some devices up to more than 300 mW at low temperature     

Very large bandwidth strained MQW DFB laser at 1.3 μm

A 3-dB bandwidth of 20 GHz has been demonstrated for a compressively strained multiquantum well InGaAsP-InP DPB laser operating at 1.3 μm. The laser displayed superior static performance including very low threshold current (~8 mA), high external quantum efficiency (0.44 mW/mA), high CW output power (>60 mW) and high temperature operation     

基于ARM半导体激光器的驱动设计及测试

在半导体激光器的使用过程中,驱动电路直接影响着激光器的稳定性。对此文中提出了一种高效、稳定,宽功率输出范围的设计方案,采用采样电阻和恒流电路实现稳定的闭环控制,得到恒定的驱动电流;利用热敏电阻温度特性,温度控制电路结合单片机控制系统,实现温度的闭环控制,从而实现了稳定的温度控制要求;结合恒温,恒流控制以及单片机系统,设计功率闭环控制方案。实验结果表明,不同温度下,功率计测得功率与驱动电流成良好的线性关系,且功率范围宽、电路可靠工作时间长、激光器单色性稳定、系统稳定性好。     

低功率激光二极管抽运的室温运转Yb:YAG激光器

报道了低功率激光二极管(LD)抽运的1030nm Yb:YAG全固态激光器。由于Yb:YAG为准三能级结构,自吸收损耗大,振荡阈值高,因此采用双路偏振耦合系统增加注入功率密度,并通过降低晶体掺杂浓度,选取合适晶体厚度,用半导体制冷器(TEC)有效制冷,在线性腔中实现了1030nm波长稳定输出。Yb:YAG晶体Yb离子掺杂原子数分数为8%,几何尺寸为11mm×0.7mm,晶体面对输出镜一端镀940nm高反膜,使未被吸收的抽运光反射回去,再次抽运晶体,从而提高了抽运光的利用效率,当注入功率为2W时,1030nm输出功率为192.8mW,光-光转换效率为9.6%,2h内稳定度小于3.5%。     

Film thickness effect on the performance of small molecular solar cell

An efficient organic photovoltaic （OPV） cell with an indium-tin-oxide/CuPc/C60/Ag structure has been investigated by changing the film thickness of organic layers. A high olin-circuit voltage （Yoc） of 0.5 V, a short-circuit current density （Jsc） of 5.81 mA/cm^2, and a high power conversion efficiency （ηp） of 1.2% were achieved at an optimum film thickness. The results demonstrate that material thickness is an important factor to cell optimization, especially for maximizing the absorption rate as will as reducing the cell resistance. Experimental results also indicate that the power conversion efficiency increases from 1.2% to 1.54% as a BCP exciton blocking layer of 10 nm is introduced.     

High slope efficiency and low noise characteristics intapered-active-stripe DFB lasers with narrow beam divergence

We report high slope efficiency and low noise characteristics in a distributed feedback (DFB) laser lasing at 1.3 μm with narrow beam divergence by employment of a laterally tapered active stripe over the whole cavity. This tapered structure is designed to realize narrow beam divergence, low threshold current, and high longitudinal mode selectivity. The fabricated tapered-active-stripe DFB lasers demonstrated of 9.20×13.40 and a record slope efficiency, for a narrow beam DFB laser, of 0.59 mW/mA. The temperature characteristics from -10°C to 85°C shows high output power at high temperature, stable single longitudinal mode oscillation and stable far-field patterns. Furthermore, for the first time ever, a low relative intensity noise characteristic of under -155 dB/Hz has been realized when butt-coupling into a single-mode fiber     

GaInAsSb-AlGaAsSb tapered lasers emitting at 2 μm

Tapered oscillators fabricated from GaInAsSb-AlGaAsSb quantum-well structure are reported for the first time. The quantum-well laser structure, grown by molecular beam epitaxy, has broad-stripe pulsed threshold current densities as low as 330 A/cm² at room temperature. One tapered laser emitting at 2.02 μm has exhibited continuous wave (CW) output power up to 750 mW, with power in the near-diffraction-limited central lobe as high as 200 mW     

Characteristics dependence on confinement structure and single-modeoperation in 2-μm compressively strained InGaAs-lnGaAsP quantum-welllasers

The optimum confinement layer structure in 2-μm compressively strained InGaAs-InGaAsP lasers is experimentally studied. Beside the carrier overflow and absorption loss in the confinement layers, the intervalence band absorption and/or Auger recombination play an important role in laser characteristics. More attention should be paid to the confinement structure to reduce the carrier density. We obtained a better laser performance with an energy difference between the bandgap of the optical confinement layer and the laser transition energy of 280-300 meV. A distributed-feedback (DFB) laser operating at 2.043 μm has been realized with the threshold current as low as 6 mA and the maximum output power of 6 mW. The differential quantum efficiency and the characteristic temperature are 16% and 59 K, respectively     

AlInAs氧化物限制1.3μm低阈值边发射激光器

研究制作了一种利用AlInAs氧化物作为限制的1.3μm边发射AlGaInAs多量子阱激光器.有源层上方和下方的AlInAs波导层被氧化作为电流限制层.这种结构提供了良好的侧向电流限制和光场限制.当电流通道为5μm宽时,获得了12.9mA的阈值电流和0.47W/A的斜率效率.与具有相同宽度的脊条的脊波导结构的激光器相比,这种AlInAs氧化物限制的激光器的阈值电流降低了31.7%,斜率效率稍微有所提高.低阈值和高效率的特性表明,氧化AlInAs波导层能够提供良好的侧向电流限制.这种AlInAs氧化物限制的激光器垂直方向的远场半高全宽角为36.1°,而水平方向的是21.6°,表明AlInAs氧化物对侧向光场也有很强的限制能力.     

976 nm高效率半导体激光器

976 nm高效率半导体激光器是这几年研究的热点,在固体激光器泵浦领域有广阔的应用。通过优化半导体激光器材料外延结构中包覆层和波导层的铝组分,降低了工作电压;通过采用微通道水冷系统,并进行优化降低了热阻,从而提高了室温下的电光转换效率。25℃室温连续测试条件下,1 cm的线阵列(巴条),2 mm腔长,50%填充因子,在110 A下,出光功率为114.2 W,电压为1.46 V,电光转换效率为71%。15条微通道封装成的垂直叠阵,进行光束整形后,获得了室温976 nm连续输出功率1 500 W,电光转换效率大于70%。     

Room temperature continuous-wave operation of GaInNAs/GaAs VCSELsgrown by chemical beam epitaxy with output power exceeding 1 mW

The authors present a near 1200 nm wavelength vertical-cavity surface-emitting laser (VCSEL) the active region of which is formed by GaInNAs/GaAs quantum wells grown by chemical beam epitaxy. Room temperature continuous-wave operation has been demonstrated with a high slope efficiency of 0.23 W/A, a high output power of over 1.0 mW, and a singlemode output power of 0.34 mW. The fabricated devices with different aperture sizes show low threshold currents of 1.2-2.1 mA and a record low threshold current density of 2.6 kA/cm² in GaInNAs VCSELs     

梯度补偿法控温晶体的高功率绿光激光器

研究了平均功率超过30W的稳定高效全固态绿光激光器,分析得出影响全固态腔内倍频激光器倍频效率和输出稳定性的主要因素是倍频晶体局部温升造成的相位失配和热透镜效应,采用温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,降低激光器工作中倍频晶体内外温度梯度从而有效地克服因晶体局部温升造成的倍频相位匹配角失配和热透镜效应。采用三条60W的半导体激光二极管阵列板条侧面抽运Nd:YAG激光增益介质棒,采用声光调Q,平凹直腔和腔内倍频结构配合温度梯度补偿控温法对大尺寸倍频晶体进行温度控制,得到了稳定高效的532nm绿光输出。在抽运电流25A,抽运功率174.6W时,得到了脉冲宽度110ns,重复频率10kHz,输出平均功率31.6W稳定高效的绿光输出,光-光转换效率为18.1%,功率稳定性为±0.66%,绿光输出光束质量因子M2=4.3。     

GaAlAs／GaAs量子阱LD泵浦Nd：YAG激光器

利用分子束外延技术生长出了ＧａＡｌＡｓ／ＧａＡｓ折射率渐变分别限制单量阱材料。用该材料作出的激光二极管作泵浦源对Ｎｄ：ＹＡＧ激光器进行端面泵浦实验，在工作电流为３．３Ａ时，ＬＤ输出功率为２．７Ｗ，得到Ｎｄ：ＹＡＧ激光器的输出功率达７００ｍＷ，光－光转换效率达２０％。