AlInGaAs垂直谐振腔顶面发射半导体激光器横向温度效应的解析热模型及其表征

依据增益导波垂直谐振腔顶面发射半导体激光器热区特点与室温连续波运行条件建立了一个优化的全解析热模型，对AlInGaAs/AlGaAs垂直谐振腔激光器的横向温度效应进行了详细的解析计算分析，其完全的解析表达展示了更加清晰的横向热场物理图像，对于器件内部热场变化规律的理论预期与实验结果完全符合. 该解析模型及其结果对于研究热稳态下的垂直谐振腔激光器热动力学特性，优化器件结构和控制激光器的阈值电流与功率温度饱和效应，特别是二维面阵器件中的横向热叠加效应提供了一个有用的工具. 关键词： 半导体面发射激光器 热效应 解析计算模型.     

Photonic crystal nanocavity laser in an optically very thick slab

A photonic crystal (PhC) nanocavity formed in an optically very thick slab can support reasonably high-Q modes for lasing. Experimentally, we demonstrate room-temperature pulsed lasing operation from the PhC dipole mode emitting at 1324 nm, which is fabricated in an InGaAsP slab with thickness (T) of 606 nm. Numerical simulation reveals that when T≥800 nm, over 90% of the laser output power couples to the PhC slab modes, suggesting a new route toward an efficient in-plane laser for photonic integrated circuits.     

Novel hybrid construction of a visible surface-emitting laser and its two-dimensional arrays

A novel hybrid surface-emitting laser and two-dimensional laser array is reported. The device consists of rectangular GaAs reflectors and edge-emitting single laser or one-dimensional laser arrays which are fabricated separately. The devices are mounted upside-down on a copper heat sink, allowing for good heat conduction. The CW operation and the reflectivity characteristics of this surface-emitting laser have been investigated.     

Graded index profiles and loss-induced single-mode characteristics in vertical-cavity surface-emitting lasers with petal-shape holey structure

The 850-nm oxide-confined vertical-cavity surface-emitting lasers with petal-shape holey structures are presented.An area-weighted average refractive index model is given to analyse their effective index profiles,and the graded index distribution in the holey region is demonstrated.The index step between the optical aperture and the holey region is obtained which is related merely to the etching depth.Four types of holey vertical-cavity surface-emitting lasers with different parameters are fabricated as well as the conventional oxide-confined vertical-cavity surface-emitting laser.Compared with the conventional oxide-confined vertical-cavity surface-emitting laser without etched holes,the holey vertical-cavity surface-emitting laser possesses an improved beam quality due to its graded index distribution,but has a lower output power,higher threshold current and lower slope efficiency.With the hole number increased,the holey vertical-cavity surface-emitting laser can realize the single-mode operation throughout the entire current range,and reduces the beam divergence further.The loss mechanism is used to explain the single-mode characteristic,and the reduced beam divergence is attributed to the shallow etching.High coupling efficiency of 86% to a multi-mode fibre is achieved for the single-mode device in the experiment.     

Vertical-cavity surface-emitting laser fabricated by two implantations using tungsten wires as mask

The design and fabrication of a room-temperature continuous wave (cw) vertical-cavity surface-emitting laser is reported. The device was fabricated by two deep H⁺ implantations using parallel tungsten wires as the resist mask. The direction of the mask in the first implantation is perpendicular to that in the second. The fabrication process is the simplest ever reported for vertical-cavity surface-emitting laser fabrication. A lowest threshold current of 17 mA and a maximum light output power of 4 mW were obtained.     

Control of light polarization in a semiconductor dual-wavelength vertical external cavity surface-emitting laser

A method for controlling the polarization characteristics of the radiation of a dual-wavelength vertical external cavity surface-emitting laser (VECSEL) is proposed. It is shown that a retarder of a special kind used as a part of the laser cavity allows the excitation of laser radiation with components in nearly mutually transverse polarization planes.     

Direct laser writing defects in holographic lithography-created photonic lattices

As a well-established laser fabrication approach, holographic lithography, or multibeam interference patterning, is known for its capability to create long-range ordered large-volume photonic crystals (PhCs) rapidly. Its broad use is, however, hampered by difficulty in inducing artificially designed defects for device functions. We use pinpoint femtosecond laser ablation to remove and two-photon photopolymerization to add desired defective features to obtain photonic acceptors and photonic donors, respectively, in an otherwise complete PhC matrix produced by holographic lithography. The combined use of the two direct laser writing technologies would immediately make holographic lithography a promising industrial tool for PhC manufacture.     

高功率InGaAs量子阱垂直腔面发射激光器的研制

采用AlAs氧化物限制工艺实验制备了衬底出光的高功率大出光窗口（直径为300 μm）InGaAs/GaAs量子阱垂直腔面发射半导体激光器,实现了器件室温准连续工作（脉冲宽度为50 μs,重复频率为1000 Hz）,并对器件的伏安特性、光输出特性、发射光谱,以及器件的远场发射特性等进行了实验测试.器件阈值电流为460mA,器件的最大光输出功率为100mW,发射波长为978.6nm, 光谱半功率全宽度为1.0 nm,远场发散角小于10°,垂直方向的发散角θ_⊥为8°,水平方向的发散角θ_∥为9°,基本为圆形对称光束.     

Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

A multi-hole vertical-cavity surface-emitting laser(VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidationconfined 850 nm VCSEL.The single-mode output power of 2.6 mW,threshold current of 0.6 mA,full width of half maximum lasing spectrum of less than 0.1 nm,side mode suppression ratio of 28.4 dB,and far-field divergence angle of about 10 are obtained.The effects of different hole depths on the optical characteristics are simulated and analysed,including far-field divergence,spectrum and lateral cavity mode.The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes,particularly for higher order modes.     

Simulation of a Single-Mode Tunnel-Junction-Based Long-Wavelength VCSEL

We investigate the physics of an internal device for a high-performance, vertical-cavity surface-emitting laser operating at 1.305 μm. Experimental results are analyzed using as the simulation software a photonic-integrated-circuit simulator in 3D (PICS3D), which is a state-of-the-art 3D simulator for surface- and edge-emitting laser diodes, semiconductor optical amplifiers, and other similar active waveguide devices. The 2D/3D semiconductor equations are coupled to the optical modes in both lateral and longitudinal directions. Optical properties such as the quantum well/wire/dot optical gain and spontaneous emission rates are computed self-consistently. Careful adjustments of material parameters led to an excellent agreement between simulation and measurements. Simulation results show that the maximum output power is limited by electron leakage from quantum wells.     

Focusing effect of a graded index photonic crystal lens

We present a new graded-index photonic crystal (GRIN PhC) structure which can be made by laser interference lithography (LIL). It can be applied as miniaturized focusing lens. Numerical simulations are carried out on the structures with different widths, lengths, and modulations. In the qualitative analysis of the focal length, focusing of a GRIN PhC was proved to originate from both the graded sizes of the rods and multimode interference. Multimode interference dominates the focusing effect when a GRIN PhC has a small length or a small difference in the rod sizes. Intensity distributions in different cases were given to support the conclusion.     

Single-mode low threshold current multi-hole vertical-cavity surface-emitting lasers

A multi-hole vertical-cavity surface-emitting laser (VCSEL) operating in stable single mode with a low threshold current was produced by introducing multi-leaf scallop holes on the top distributed Bragg-reflector of an oxidation-confined 850 nm VCSEL. The single-mode output power of 2.6 mW, threshold current of 0.6 mA, full width of half maximum lasing spectrum of less than 0.1 nm, side mode suppression ratio of 28.4 dB, and far-field divergence angle of about 10° are obtained. The effects of different hole depths on the optical characteristics are simulated and analysed, including far-field divergence, spectrum and lateral cavity mode. The single-mode performance of this multi-hole device is attributed to the large radiation loss from the inter-hole spacing and the scattering loss at the bottom of the holes, particularly for higher order modes.     

Practical Accurate Optical Ranging Based on Polarization Self Modulation of a Vertical-Cavity Surface-Emitting Laser Diode

A self-mixing type range finder is proposed using the polarization self modulation phenomenon of a vertical-cavity surface-emitting laser diode, in which the polarization mode switches between two inherent modes of the laser diode. The length to be measured is determined from the switching frequency, the accuracy of which is quite excellent with a relative error of less than 10 ppm. Experimental results prove that the present method is feasible as a practical and highly accurate ranging technique.     

Modeling of resistance characteristics of a continuously-graded distributed Bragg reflector in a 980-nm vertical-cavity surface-emitting laser

The resistance characteristics of a continuously-graded distributed Bragg reflector(DBR) in a 980-nm verticalcavity surface-emitting laser(VCSEL) are modeled in detail.The junction resistances between the layers of both the p-and n-DBR mirrors are analysed by combining the thermionic emission model and the finite difference method.In the meantime,the intrinsic resistance of the DBR material system is calculated to make a comparison with the junction resistance.The minimal values of series resistances of the graded p-and n-type DBR mirrors and the lateral temperature-dependent resistance variation are calculated and discussed.The result indicates the potential to optimize the design of the DBR reflectors of the 980-nm VCSELs.     

Spectral and modulation properties of a largely tunable MEMS-VCSEL in view of gas phase spectroscopy applications

An extensive characterization of the spectral properties of a largely tunable laser in the 1.56-μm spectral range is reported. This device combines a vertical-cavity surface-emitting laser (VCSEL) with a micro-machined (MEMS) Bragg mirror in a very compact arrangement. The large tunability obtained by an electro-thermal actuation of the MEMS mirror makes this device very attractive for high-resolution spectroscopy. Relevant laser parameters for the implementation of wavelength modulation spectroscopy techniques in gas sensing, such as tuning and modulation properties, are presented. A preliminary gas spectroscopy experiment performed with this laser is also shown.     

Linewidth narrowing caused by optical feedback in a multi-mode vertical-cavity surface-emitting laser

We have studied experimentally spectral characteristics of a multi-mode vertical-cavity surface-emitting laser that is subject to optical feedback. Appropriate alignment of the feedback mirror can suppress higher-order modes and significantly decrease the spectral linewidth of the laser.     

Observation of low-frequency fluctuations in vertical-cavity surface-emitting lasers

Low-frequency fluctuations, which are typical irregular oscillations in edge-emitting semiconductor lasers, are experimentally observed for the y-polarization mode (y is the direction along the optical axis of a laser material) in a vertical-cavity surface-emitting laser with optical feedback.     

基于光电负反馈的光注入1550nm垂直腔面发射激光器产生窄线宽微波信号

基于1 550nm垂直腔面发射激光器在平行偏振光注入下呈现的单周期非线性动力学状态,进一步引入光电负反馈,得到了高质量的微波信号.实验研究结果表明:平行偏振光注入下,通过调节注入光的注入强度及频率,1 550nm垂直腔面发射激光器可呈现注入锁定、单周期、倍周期、混沌等多种非线性动力学状态;在合适的注入参量下,平行偏振光注入1 550nm垂直腔面发射激光器可产生光谱具有单边带结构、频率超过10GHz的光子微波信号,但该微波信号的线宽较宽(达MHz量级);进一步引入光电负反馈后,通过选取合适的光电反馈强度,可将该微波信号的线宽减小至一百多kHz(减小两个量级以上);在选择优化的反馈强度条件下,仅通过简单调节注入光强度,可实现窄线宽光子微波信号的频率在一定范围内连续可调谐.     

Planar defects in three-dimensional chalcogenide glass photonic crystals

Here we report on the direct laser writing fabrication of Fabry-Perot-type planar microcavities in a three-dimensional (3D) photonic crystal (PhC) embedded within a high-refractive nonlinear chalcogenide glass (ChG) film. The fabricated planar microcavities in a nonlinear ChG 3D PhC facilitate the observation of resonant modes inside the stop gap. The experimental results show that the length of the planar cavity can be well controlled by the fabrication power and thus be used to tune the defect modes. The tunability of the observed defect modes is confirmed by the theoretical prediction.     

Single polarization, single transverse mode, and widely tunable narrow-linewidth laser from a multimode vertical cavity surface-emitting laser by use of a coupled cavity

A simple method for achieving a widely tunable narrow-linewidth, single polarization state and single transverse mode lasing oscillation from a commercially available multimode vertical cavity surface-emitting laser by use of a coupled cavity is reported. The laser has a wavelength tuning range of more than 5 nm along 850 nm, a side-mode suppression ratio of approximately 15 dB, and an output power of approximately 0.3 mW from a 50-microm multimode optical fiber at a bias current of 15 mA. The laser was operated in a single state of polarization lasing oscillation without any polarization switching.