Heat-source distribution in etched-well surface-emitting semiconductor lasers

The authors report on the development of a comprehensive self-consistent thermal-electrical model of etched-well vertical-cavity surface-emitting lasers. The analysis provides valuable insight into distribution of heat sources in these devices. Two-dimensional current- and heat-spreading analysis is used to determine in a self-consistent manner a realistic distribution of heat sources in etched-well vertical-cavity surface-emitting lasers. Strong nonuniformities of heat-source and temperature distributions are revealed. The relative contributions of various heat sources are evaluated. The Joule heating of the p-AlGaAs cladding layer is identified as a major cause of intense heating above threshold.<>     

Low-threshold lasers fabricated by alignment-free impurity induceddisordering

An Si/SiN_x/Si trilayer diffusion source and mask is described and applied to an alignment-free process for fabricating lasers by impurity-induced disordering (IID). Edge-emitting lasers with continuous wave threshold currents of 4.8 mA were achieved, and folded-cavity surface-emitting lasers with Si disordered waveguides were demonstrated for the first time with a threshold of 11 mA. The process that makes possible self-aligned-metallization on a diffusion defined stripe will be useful in fabricating narrow stripe IID lasers and simplify processing for integration of IID waveguide devices     

Low-threshold native-oxide confined narrow-stripe folded-cavity surface-emitting InGaAs-GaAs lasers

Narrow-stripe folded-cavity surface-emitting InGaAs-GaAs lasers are demonstrated, AlAs native-oxide layers above and below waveguide region are employed for current and optical confinement to form narrow-stripe InGaAs-GaAs quantum-well lasers. A low-temperature (400/spl deg/C) selective wet-oxidation technique and an ion-beam-etching technique are used to fabricate insulator confined narrow-stripes and internal 45/spl deg/ deflectors, respectively. Continuous-wave threshold currents as low as 4.5 mA and 59% surface-emitting quantum efficiencies are achieved on the devices with 2-/spl mu/m-wide aperture and a 420-/spl mu/m-long cavity.     

Vertical-External-Cavity Surface-Emitting Laser With Monolithically Integrated Pump Lasers

The monolithic integration of pump lasers and optically pumped vertical-external-cavity surface-emitting lasers is demonstrated. An innovative contacting scheme for the pump lasers offers high design flexibility and scalability. First devices at 1000 nm generate output powers of 2.5 W in pulsed and 0.65 W in continuous-wave operation.     

Fresnel analysis of effective mirror reflectivity in folded-cavityin-plane surface-emitting lasers

Inside-cavity diffraction loss resulting from unguided regions and 45° internal total reflection mirror(s) is an important issue for fabricating folded-cavity in-plane surface-emitting lasers. A Fresnel plane-wave decomposition method was applied to analyze this problem. The effective reflectivity of an angle-etched mirror was calculated for deviation of the etched angle and different lengths of the unguided region. The results offer design criteria for fabricating folded-cavity surface-emitting lasers as well as other devices with angle-etched facet(s) for surface normal light coupling     

Cascadable surface-emitting laser logic: demonstration of Boolean logic

The authors demonstrate cascadable optical logic (AND-, OR- and exclusive OR-gates) implemented with heterojunction phototransistors and vertical-cavity surface-emitting lasers. They also discuss an architecture for implementing binary arithmetic using cascadable surface-emitting laser logic devices and optical symbolic substitution.<>     

High-efficiency, high-speed VCSELs with 35 Gbit=s error-free operation

High-efficiency, high-speed, tapered-oxide-apertured 980 nm vertical-cavity surface-emitting lasers (VCSELs) with 35 Gbit/s error-free operation have been demonstrated. This is the highest data rate reported for directly modulated VCSELs to date. The devices are also highly efficient, showing a record-high data-rate/power-dissipation ratio of 3.5 Gps/mW.     

Small-dimension power-efficient high-speed vertical-cavity surface-emitting lasers

Small-dimension power-efficient high-speed oxide-confined 980 nm vertical-cavity surface-emitting lasers (VCSELs) with record-high bandwidth/power-dissipation ratio of 12.5 GHz/mW have been demonstrated. The devices show a modulation bandwidth of 15 GHz at a bias current 0.9 mA, corresponding to only 1.2 mW power dissipation     

Low-threshold, high-power, 1.3-μm wavelength, InGaAsP-InPetched-facet folded-cavity surface-emitting lasers

A 1.3-μm wavelength, InGaAsP-InP folded-cavity, surface-emitting laser with CH₄-H₂ reactive ion-etched vertical and 45° angled facets was demonstrated for the first time. Continuous-wave threshold currents of 32 mA have been achieved, with >15 mW CW power for the surface-emitted light. These surface-emitting lasers with two dry-etched facets are suitable for wafer-level testing and for monolithic integration with other InP-based photonic devices     

太赫兹波的几个基本问题

介绍了用于加工太赫兹波元件的微机械加工技术(铣削、放电加工、电铸、湿法腐蚀Si、干法腐蚀Si、厚光刻胶:SU-8和LIGA)及其最新结果。重点描述了应用于太赫兹波的器件和集成电路,如将可用于太赫兹波的各种新颖二极管、半导体纳米器件、新的高电子迁移率晶体管、毫米波集成电路、量子器件、红外器件、量子级联激光器(单极级间跃迁激光器)。基于带间跃迁量子机理的半导体器件(譬如量子级联激光器)的频率极限高于与半导体能带隙相关器件的频率,其大多数体半导体的频率可以达到10THz以上。但是,基于经典的电子扩散传输机理的二极管、三极管的高频极限则受限于渡越时间和寄生参数RC时间常数。     

Polarization stability of phase-locked arrays of vertical-cavitysurface-emitting lasers

The polarization stability of the fundamental lasing super-mode obtained from coherently coupled arrays of vertical-cavity surface-emitting lasers has been investigated. Various devices have been analyzed and none showed the abrupt change of the polarization direction (flip) often observed in solitary devices. This polarization stability is due to a current independent dichroism of 0.5 GHz     

半导体可饱和吸收镜实现超短高功率脉冲激光研究进展

介绍了半导体可饱和吸收镜(SESAM)的基本结构及使用半导体可饱和吸收镜被动锁模固态激光器的基本原理.综述了利用半导体可饱和吸收镜被动锁模薄片式固态激光器及光泵浦垂直外腔面发射半导体激光器,获得高平均输出功率超短脉冲的最新进展,并指出量子点半导体可饱和吸收镜的使用将加速超短高功率脉冲的发展.     

High-power InGaAs/GaAs 1.3 μm VCSELS based on novel electrical confinement scheme

Reported are 1.3 mum InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with a novel electrical confinement scheme based on lithographic definition and selective area epitaxial regrowth in the cavity region. More than 6 mW of output power with a record high differential efficiency of more than 70% is emitted from 10 mum large devices.     

Design and characterization of In0.2Ga0.8AsMQW vertical-cavity surface-emitting lasers

The device design, material characterization, and performance of optimized vertical-cavity surface-emitting lasers (VCSELs) are presented. The basic design goal was to increase the output power of the lasers without greatly increasing the low threshold current reported in earlier devices. The material characterization was performed by measuring in-plane lasers and broad-area VCSELs made from the same material as the small VCSELs. For 10-μm-square devices, outputs over 3 mW, device operation over 100°C, 6% wall-plug efficiency, threshold voltages under 3 V, and threshold currents under mA are reported     

Wafer-bonded bottom-emitting 850-nm VCSEL's on GaP substrates

Bottom-emitting 850-nm vertical-cavity surface-emitting lasers were fabricated using wafer bonding technology to replace the absorbing GaAs substrates with transparent GaP substrates. Ohmic-like p-type GaAs-GaP bonded interfaces were obtained with proper bonding condition. The devices with 4×4 μm² current aperture exhibit 24% external quantum efficiency, and threshold current as low as 400 μA. The threshold voltages range from 1.71 to 1.8 V for different aperture size devices     

VCSELs with a self-aligned contact and copper-plated heatsink

Top-emitting, 850-nm vertical-cavity surface-emitting lasers with a self-aligned top contact and evaporated gold or plated copper heatsink were fabricated and characterized. Thermal resistance was reduced by 44%, and output power and bandwidth were increased by 38% and 12%, respectively. The fabricated devices exhibit a 3-dB modulation frequency bandwidth up to 16.3 GHz at 10 kA/cm/sup 2/.     

Antiphase complex-coupled surface-emitting distributed feedbackdiode lasers with absorptive gratings

Theoretical analysis of antiphase-type complex-coupled, surface-emitting distributed feedback (CC-SE-DFB) diode lasers with absorptive gratings is presented and discussed. Two different designs are studied: one utilizing a semiconductor-based second-order loss and index grating placed at the metal-semiconductor (p-side) interface, and the other employing a combination of metallic and semiconductor materials for the second-order loss and index grating. For certain design parameters, these two types of absorptive-grating structure are shown to select lasing in the symmetric mode (i.e., orthonormal emission in a single-lobe beam pattern). By comparison to metal-grating surface-emitting devices, the threshold gains for these structures are lower by factor of 3 to 4. For 500-μm-long gratings, the symmetric-mode is favored to lase with threshold gain values as low as 18 cm^-1 and differential quantum efficiency as high as 34%     

Long-term spectral stability of singlemode VCSELs

The long-term spectral stability of 780 nm AlGaAs-based vertical-cavity surface-emitting lasers has been investigated. The 28 devices from two different wafers show a thermally induced averaged total spectral shift of 75±9 and 47±7 GHz, respectively     

Polyimide-planarized vertical-cavity surface-emitting lasers with 17.0-GHz bandwidth

High-speed oxide-confined polyimide-planarized 850-nm vertical-cavity surface-emitting lasers exhibit -3-dB modulation bandwidths up to 17.0 GHz. The devices are fabricated using a reproducible, simple process incorporating polyimide with good adhesion that does not require implantation or semiinsulating substrates to achieve low capacitance.     

Vertical-cavity surface-emitting lasers with lateral carrier confinement

A novel method to reduce threshold currents in vertical-cavity surface-emitting lasers (VCSELs) is proposed. By using selective quantum well intermixing, lateral heterobarriers are created that prevent carriers from diffusing away from the optical modes. Our devices show 40% reduction of threshold currents with the implementation of lateral carrier confinement