低偏振灵敏度半导体光放大器

报道了基于混合应变量子阱材料的半导体光放大器 (SOA)。利用张应变量子阱加强了TM模的增益 ,使之接近TE模的增益 ,从而使SOA的偏振灵敏度大为降低。在 150mA的偏置下 ,获得了 2 4dB的小信号增益和 1dB的偏振灵敏度。     

量子阱半导体光放大器的增益偏振相关性研究

应用能带计算理论,研究了张应变量大小、量子阱厚度对量子阱半导体光放大器(SOA)中的增益偏振相关性的影响.采用张应变量子阱为有源区,设计了增益偏振无关的1.55 μm的SOA,它可以在较宽的载流子浓度范围、较宽的光波长范围内满足增益对偏振的不灵敏要求.另外,还采用混合应变量子阱为有源区,设计了增益偏振无关的1.31μm的SOA.     

量子阱材料折射率低偏振相关性研究

分析了阱宽、垒高和应变对量子阱材料TE模和TM模折射率的影响,并剖析了其中的物理机理.研究表明:对于量子限制效应带来的量子阱折射率偏振相关性,阱宽越小或垒高越高,折射率偏振相关性越大.压应变增大时,折射率偏振相关性增大,张应变可以克服量子限制效应带来的折射率偏振影响.对于不同阱宽和垒高的量子阱,均存在合适的张应变量使折射率偏振相关性最小,且阱宽越小或垒高越高所需的张应变量越大.根据以上分析,提出量子阱材料折射率低偏振相关设计方法,并据此设计出C波段(1 530～1 565 nm)内折射率低偏振相关(小于0.03)的量子阱材料In0.49Ga0.51As/In0.77Ga0.23As0.5P0.5.研究结果有助于优化设计光网络中关键器件.     

覆盖S+C波段的宽光谱带宽InGaAlAs/InP量子阱结构

通过理论仿真和实际制备测试,分析比较了基于非对称量子阱结构(10 nm厚和6 nm厚的量子阱组合)的光放大芯片与对称量子阱结构(10 nm厚量子阱)的光放大芯片的性能。两种结构的理论模式增益同最终实测值符合较好。最终光谱测试结果显示,对称量子阱结构的光放大芯片存在基态增益饱和的现象,在大电流注入情况下,激态跃迁占据优势,从而造成光谱宽度急剧下降。而非对称量子阱结构的光放大芯片的光谱宽度随着注入电流的增加不断拓宽,在600 mA下实现199.7 nm光谱带宽,覆盖S+C波段。由此可见,非对称量子阱结构更有利于实现高功率、宽光谱的光放大芯片。     

1550 nm波段外腔窄线宽激光器增益芯片

针对外腔窄线宽激光器应用设计了一款半导体增益芯片，分析了斜率效率和增益谱特性，由于封装后增益峰红移会造成器件输出功率下降，指出设计中芯片的增益峰需偏离激光器激射波长。通过优化量子阱结构及材料应力，提高了芯片的斜率效率。为了降低芯片自身法布里-珀罗(FP)腔谐振效应，采用弯曲波导配合磁控溅射四层增透膜工艺，使芯片出光端面的有效反射率明显降低，提高了窄线宽激光器输出波长的稳定性。所设计芯片采用1%压应变量子阱材料，量子阱厚度为7.5 nm,量子阱数量为3个，芯片波导与解理面法线呈6°夹角。通过半导体流片工艺完成掩埋结芯片制作，并进行窄线宽激光器封装及测试，实现了1 550 nm波段高效稳定的窄线宽激光输出。     

1310nm大功率高偏振度量子阱超辐射发光二极管

设计并制备了一种斜条脊波导结构压应变高偏振度多量子阱超辐射发光二极管.设计的脊波导出光面TiO2/SiO2四层宽带增透膜的TE模式反射率约为10-6,分析了脊波导角度偏差和膜层厚度偏差对增透膜反射率的影响.实验结果表明,在250 mA直流电流驱动下,所设计的超辐射发光二极管芯片单管输出功率可达22.7 mW,出射光谱FWHM约为37.3 nm,光谱纹波系数低于0.15 dB,TE模式输出光强占主导,偏振度约为19.2 dB.     

多量子阱有效折射率偏振相关性研究

分析了多量子阱材料各参数对其TE模和TM模有效折射率的影响。结果表明:阱数增多,多量子阱有效折射率降低,当量子阱数目大于3时,其有效折射率的变化不明显。垒厚增加,有效折射率略有降低。存在合适的张应变量使TE模和TM模有效折射率峰值波长接近的同时,折射率差值整体最小,偏振相关性最小。据此提出多量子阱材料有效折射率低偏振相关设计方法,并设计出C波段内(1530~1565 nm)折射率低偏振相关的InGaAs/InGaAsP多量子阱材料。研究结果有助于设计实用化的有效折射率低偏振相关量子阱材料。     

1.3μm高增益偏振无关应变量子阱半导体光放大器

采用低压金属有机化学气相外延法 (LP MOVPE)生长并制作了 1 3μm脊型波导结构偏振无关半导体光放大器 (SOA) ,有源区为基于四个压应变量子阱和三个张应变量子阱交替生长的混合应变量子阱 (4C3T)结构 ,压应变阱宽为 6nm ,应变量 1 0 % ,张应变阱宽为 11nm ,应变量 - 0 95 % ;器件制作成 7°斜腔结构以有效抑制腔面反射。半导体光放大器腔面蒸镀Ti3 O5/Al2 O3 减反 (AR)膜以进一步降低腔面剩余反射率至 3× 10 -4以下 ;在 2 0 0mA驱动电流下 ,光放大器放大的自发辐射 (ASE)谱的 3dB带宽大于 5 0nm ,光谱波动小于 0 4dB ,半导体光放大器管芯的小信号增益近 30dB ,在 12 80～ 1340nm波长范围内偏振灵敏度小于 0 6dB ,饱和输出功率大于 10dBm ,噪声指数 (NF)为 7 5dB。     

1.55μm张应变InGaAsP/InGaAsP量子阱偏振不灵敏半导体光放大器的优化设计

优化设计了1.55μm InGaAsP/InGaAsP张应变量子阱偏振不灵敏半导体光放大器的结构.利用k*p方法计算了多量子阱的价带结构,计算中考虑了6×6有效质量哈密顿量.从阱宽、应变、注入载流子密度等方面计算了量子阱模式增益的偏振相关性.     

808nm InGaAlAs垂直腔面发射激光器的结构设计

为实现垂直腔面发射半导体激光器(VCSEL)在808 nm波长的激射,对VCSEL芯片的整体结构进行了设计。基于应变量子阱的能带理论、固体模型理论、克龙尼克-潘纳模型和光学传输矩阵方法,计算了压应变InGaAlAs量子阱的带隙、带阶、量子化子能级以及分布布拉格反射镜(DBR)的反射谱,从而确定了量子阱的组分、厚度以及反射镜的对数。数值模拟的结果表明,阱宽为6 nm的In0.14Ga0.74Al0.12As/Al0.3Ga0.7As量子阱,在室温下激射波长在800 nm左右,其峰值材料增益在工作温度下达到4000 cm-1;渐变层为20 nm的Al0.9Ga0.1As/Al0.2Ga0.8As DBR,出光p面为23对时反射率为99.57%,全反射n面为39.5对时反射率为99.94%。设计的顶发射VCSEL结构通过光电集成专业软件(PICS3D)验证,得到室温下的光谱中心波长在800 nm处,证实了结构设计的正确性。     

高增益偏振不灵敏InGaAs/InP体材料半导体光放大器

采用三元InGaAs体材料为有源区，通过直接在InGaAs体材料中引入0．20％张应变来加强TM模的增益，研制了一种适合于作波长变换器的偏振不灵敏半导体光放大器(SOA)。在低压金属有机化学气相外延(LPMOVPE)的过程中，只需调节三甲基Ga的源流量便可获得所要求的张应变量。制作的半导体光放大器在200mA的注入电流下，获得了50nm宽的3dB光带宽和小于0．5dB的增益抖动；重要的是，半导体光放大器能在较大的电流和波长范围里实现小于1．1dB的偏振灵敏度。对于1．55gm波长的信号光，在200mA的偏置下，其偏振灵敏度小于1dB，同时获得了大于14dB光纤到光纤的增益，3dBm的饱和输出功率和大于30dB的芯片增益。用作波长变换器，可获得较高的波长变换效率。进一步提高半导体光放大器与光纤的耦合效率，可得到性能更佳的半导体光放大器。     

Gain saturation properties of a polarization insensitivesemiconductor amplifier implemented with tensile and compressive strainquantum wells

The gain saturation properties of a 1.3 μm polarization insensitive semiconductor amplifier implemented with tensile and compressive strain quantum well active region are experimentally investigated in order to determine how well the amplifier maintains its polarization insensitivity in the saturation regime. The amplifier has unsaturated gain of 12 dB and in the saturation regime the maximum observed gain imbalance between TE and TM gains is 0.9 dB. The measured 3 dB saturation output power is 5 mW     

Complete polarization mode control of long-wavelength tunable vertical-cavity surface-emitting lasers over 65-nm tuning, up to 14-mW output power

We experimentally demonstrate a stable polarization mode operation in long-wavelength tunable vertical-cavity surface-emitting lasers over a 65-nm tuning range and the entire output power range (< 14.6 mW) at room temperature. The polarization mode control was achieved by utilizing anisotropic gain properties of quantum wells due to the difference in bond lengths between the constituent atoms at the interfaces combined with uni-axial external strain induced by a stressor. The experiments were conducted to verify this newly proposed polarization control scheme based on the spin flip model (SFM) developed to incorporate the detailed gain properties, cavity standing wave effect, self-heating effect, and strain effect. The experimental results on the tuning characteristics of polarization switching behavior and output powers were reproduced in highly agreeable manner by simulations. The relative importance of the external strain, interfacial strain at quantum wells, and the wavelength dependence of gain anisotropy are also discussed. It is also shown that the fast spin relaxation times for InP-based vertical-cavity surface-emitting lasers (VCSELs) was responsible for the inhibition of elliptic polarization states often observed for GaAs-based VCSELs. The effectiveness of the polarization control scheme was highlighted by the observed high polarization suppression ratio of 34 dB maintained for the entire wavelength and pump power ranges during the reliability testing over 2000 h. The influence of the elliptic polarization state for the optical pump laser was detected which could be explained as a memory effect of the spin-polarized electrons, supporting the validity of the SFM.     

27-dB gain unidirectional 1300-nm polarization-insensitive multiplequantum well laser amplifier module

An unidirectional polarization-insensitive multiple quantum well laser amplifier module for the 1300-nm window with a record high gain of 27 dB and a 3-dB saturation output power of 13 dBm is demonstrated. The module gain has a 3-dB width exceeding 60 nm and shows a typical polarization sensitivity and gain ripple as low as 0.3 dB. To provide immunity for backscattered or reflected light, polarization independent optical isolators were inserted in the input and output coupling optics of the package. A practical optical amplifier module for the 1300-nm window is very desirable, because most of the presently installed fiber has its zero dispersion wavelength around 1310 mm, while much of the older fiber often only can be operated around this wavelength     

适于InGaAsP光放大器偏振不灵敏的增益介质

研制了适于InGaAsP光放大器偏振不灵敏的增益介质 ,采用有源区内交替的张应变和压应变排列的混合应变量子阱结构 ,器件做成带有倾角的扇形。实验中发现该结构既抑制了激射又改善了器件的偏振灵敏性 ,实现了偏振灵敏度小于 0 5dB ,10 0mA偏置时可达 0 1dB。在较大的电流范围内 ,峰的半高全宽 (FWHM)为 4 0nm。     

940 nm高功率半导体激光器研究

报道了一种采用大光学腔结构的InGaAs/GaAs/AlGaAs应变量子阱高功率半导体激光器。在量子阱能级本征值方程的数值求解基础上 ,优化了InGaAs阱层材料的In组份含量 ;采用大光学腔结构以有效降低垂直于结平面方向的光束发散角及腔面的光功率密度 ,实现器件的高功率、低发散角光。设计的激光器外延结构采用分子束外延 (MBE)方法生长 ,成功获得具有较低激射阈值的 94 0nm波长激光器外延片。对 10 0 μm条形 ,10 0 0 μm腔长的制备器件测试表明 ,器件的最大连续输出功率达到 2W ,峰值波长为 939.4nm ,远场水平发散角为 10° ,垂直发散角为 30°。器件的阈值电流为 30 0mA。     

外腔面发射激光器自发辐射谱的热特性

热效应是限制外腔面发射激光器(VECSEL)输出功率和光束质量的主要原因。为了优化VECSEL增益芯片有源区量子阱的设计,降低激光器的热效应,提高斜效率和输出功率,采用光致荧光谱方法,对设计波长980nm VECSEL自发辐射谱的热特性进行了实验研究。取得了不同热沉温度下边发射和面发射谱随温度的变化数据。结果表明,反映有源区量子阱自身特性的边发射谱峰值波长随温度升高的红移速率是0.5nm/K,而受到增益芯片多层结构调制的面发射谱峰值波长随温度升高的红移速率只有0.1nm/K;由于受到VECSEL增益芯片中微腔的限制,面发射谱分离为多个模式,分别与微腔的腔模对应。可见对量子阱的发射波长及微腔腔长做预偏置优化处理,可以显著改善激光器的输出性能。     

808nm高效率激光二极管

目前808nm高效率激光二极管产品的转换效率只有50%左右,还有很大的提升空间。通过提高欧姆接触层浓度、界面渐变和波导层掺杂等方面的外延材料结构优化,减小附加电压和电阻值,设计制作了808nm大光腔应变量子阱外延材料;并制作了200μm发光区标准单管,提取了材料内部参数,材料内损耗iα为0.67cm-1,内量子效率iη为0.88;将圆片解理成2mm腔长的巴条进行腔面镀膜,并烧结成标准单管,25℃下单管电光效率达到61.1%;将巴条烧结到微通道载体上,制作成标准微通道水冷单条阵列,水温15℃110A下输出光功率126.6W,电光转换效率62.77%。     

Barrier composition dependence of differential gain and externaldifferential quantum efficiency in 1.3-μm strained-layermultiquantum-well lasers

Dependence of the differential gain and the external differential quantum efficiency on the composition of InGaAsP barrier layers were investigated for 1.3 μm InGaAsP-InGaAsP compressively strained layer (SL) multiquantum well (MQW) lasers. In this investigation, we compared between SL-MQW lasers and unstrained MQW lasers having the same well thicknesses and the same emitting wavelength in order to clarify the effect of strain for each barrier composition. As a result It has been found that the barrier composition has large influence on the differential gain and the external differential quantum efficiency in the SL-MQW lasers. Narrower band-gap barrier means little effect of strain on the differential gain due to the electron overflow from a well layer, while wider band-gap barrier means degradation in the differential gain and the external differential quantum efficiency due to the nonuniform injection of hole into a well layer. In this experiment, the barrier composition of 1.05 μm is suitable for 1.3 μm InGaAsP-InGaAsP SL-MQW lasers to realize large differential gain and high external differential quantum efficiency simultaneously     

1.55 mu m polarization-insensitive high-gain tensile-strained-barrier MQW optical amplifier

A polarization-insensitive semiconductor optical amplifier was realized at a wavelength of 1.55 mu m. The active layer consisted of a tensile-strained-barrier multiple quantum well (MQW) structure. At a driving current of 150 mA, no dependence of the saturation characteristics on modes was obtained. The saturation output power at which the gain decreases 3 dB is 13.3 dBm. A slightly higher saturation output power of 14 dBm was measured at a driving current of 200 mA. No large difference was observed between transverse-electric (TE) and transverse-magnetic (TM) modes. A high gain of 27.5 dB at a polarization sensitivity of 0.5 dB and a high saturation output of 14 dBm were realized simultaneously by using a longer device with reduced residual facet reflectivities.<>