InGaAs vertical-cavity surface-emitting lasers

The authors give theoretical and experimental results for vertical-cavity surface-emitting lasers (VCSELs). The modeling is applied to the design of InGaAs VCSELs. A simple method to calculate the reflectivity of semiconductor stack mirrors with graded interfaces and compound metal/semiconductor stack mirrors is introduced. The theoretical predictions are compared to results from actual device measurements. A novel technique is introduced to determine material parameters: fabrication of in-plane lasers from VCSEL material. The procedure used to determine the optical mode in such an in-plane laser is described. Using the insight gained from modeling, the external efficiency was increased to >30% with a threshold current density of 1 kA/cm²     

高光束质量大功率垂直腔面发射激光

大功率垂直腔面发射激光器(VCSEL)在激光泵浦、激光测距、激光雷达等领域有广泛的应用前景,但目前的常规激光器材料结构尚未针对大功率激光输出进行优化设计。特别是为获得大功率激光输出所采用的大出光窗口导致的激光光束质量劣化成为限制其应用发展的核心问题之一。针对上述问题对激光器材料结构与器件结构进行了两方面的新结构设计和研制:(1)以实现大功率激光输出为目标,材料结构设计上对出光窗口一侧的N-DBR反射率进行了调整,以具有99.3%反射率的n-DBR替代常规结构中所采用的99.7%以上反射率。与常规材料结构相比,采用优化后的材料结构制备的直径500μm出光孔径的单管器件在注入电流110 A时激光输出功率达到102 W,而单元出光窗口直径100μm的5×5阵列在100 A电流下的激光输出功率为103 W,单元直径为140μm的8×8阵列在130 A注入电流下的激光输出功率达到115 W;(2)针对大出光窗口导致的光束质量劣化,通过湿法化学刻蚀研制了直接集成在出光窗口表面的微透镜结构,单元出光窗口直径为90μm的6×6阵列器件在4 A注入电流下的激光光束发散角压缩到6.6°,与未集成微透镜时的14.8°相比有了大幅改善。实验结果表明:降低n-DBR反射率及集成微透镜结构有效地改善提高了大功率垂直腔面发射激光的输出功率和激光光束质量。     

High-power single-mode selectively oxidized vertical-cavity surface-emitting lasers

Single-mode vertical-cavity top-surface-emitting lasers with maximum output power of 2.7 mW and side-mode suppression of 50 dB have been fabricated using solid source MBE for growth and selective oxidation to define the 3-/spl mu/m diameter active area. Threshold current is 290 /spl mu/A and a maximum wallplug efficiency of 27% is obtained at an output power of 1 mW.     

High-power single-mode antiresonant reflecting optical waveguide-type vertical-cavity surface-emitting lasers

Antiresonant reflecting optical waveguide (ARROW) techniques are employed in vertical cavity surface emitting lasers (VCSELs) to achieve high-power single-mode emission. Using the effective-index method and fiber mode approximation, the cold-cavity lateral modal behavior for the circular shaped ARROW VCSEL demonstrates significant reduction of radiation loss from that of a single antiguide, while maintaining strong discrimination against high-order modes. The circular-waveguide is created by selective chemical etching and two-step metal-organic chemical vapor deposition growth, with proton implantation used to confine the current injection to the low-index core region. A single-mode CW power of 7.1 mW has been achieved from an 8 /spl mu/m diameter ARROW device (index step /spl Delta/n = 0.05, emission at /spl lambda//sub 0/ = 980 nm) with a far-field FWHM of 10/spl deg/. Larger aperture (12 /spl mu/m) devices exhibit multimode operation at lower drive currents with a maximum single-mode continuous-wave output power of 4.3 mW.     

InGaAs/GaAs vertical-cavity surface-emitting lasers on (311)B GaAssubstrate

InGaAs/GaAs vertical cavity top-emitting dielectric-mirror surface-emitting lasers have been fabricated on a (311)B GaAs substrate. The threshold current was 25 mA at a lasing wavelength of 0.97 μm under pulsed operation at room temperature. The output was linearly polarised in the [2¯33] direction     

Vertical-cavity surface-emitting lasers based on submonolayer InGaAs quantum dots

Molecular beam epitaxy-grown 0.98-/spl mu/m vertical-cavity surface-emitting lasers (VCSELs) with a three-stack submonolayer (SML) InGaAs quantum-dot (QD) active region and fully doped Al/sub x/Ga/sub 1-x/As-GaAs DBRs was studied. Large-aperture VCSELs demonstrated internal optical losses less than 0.1% per one pass. Single-mode operation throughout the whole current range was observed for SML QD VCSELs with the tapered oxide apertures diameter less than 2 /spl mu/m. Devices with 3-/spl mu/m tapered-aperture showed high single-mode output power of 4 mW and external quantum efficiency of 68% at room temperature.     

Continuous wave operation of 1.26 μm GaInNAs/GaAsvertical-cavity surface-emitting lasers grown by metalorganic chemicalvapour deposition

Electrically pumped near 1.3 μm GaInNAs/GaAs vertical-cavity surface-emitting lasers grown by metalorganic chemical vapour deposition are demonstrated for the first time. The threshold current and voltage under continuous wave operation of a 10×10 μm² oxide aperture device were 7.6 mA and 2.8 V, respectively. The output power exceeded 0.1 mW and the slope efficiency was ~0.1 W/A     

High-power highly strained InGaAs quantum-well lasers operating at1.2 μm

High-power highly strained In_xGa_1-xAs quantum-well lasers operating at 1.2 μm are demonstrated. The edge emitting broad area (BA) laser diode structures are grown by metal organic vapor phase epitaxy at low growth temperatures using trimethylgallium, trimethylindium, and arsine sources. In the laser structure, an InGaAs QW is sandwiched between the GaAs waveguide and AlGaAs cladding layers. The operating wavelength for the laser diode at room temperature (20°C) is about 1206 nm, which redshifts to 1219 nm at 46°C. The transparency current density for the BA laser diodes is as low as 52 A/cm² and the characteristic temperature value is 76 K. High-power laser operation in the pulse mode (about 1.6 W) at room temperature was achieved     

Bow-tie surface-emitting lasers

We report a new design for surface emitting semiconductor lasers operating at 940 nm, incorporating a double-flare cavity, and distributed Bragg reflector (DBR) mirrors also providing surface emission. This design can take advantage of the modal behavior of the unstable resonator, and has shown very good mode control, with coherent emission from two facets in the same direction. We report preliminary performance results showing very promising characteristics including single-mode diffraction limited operation, and spectral behavior with 42 dB side-mode suppression. This design has exhibited promising results for increasing the current range between the lasing threshold and the filament threshold     

High-power (>0.5-W CW) diode-pumped vertical-external-cavity surface-emitting semiconductor lasers with circular TEM/sub 00/ beams

We report demonstration of a new high-power semiconductor laser technology, the optically pumped semiconductor (OPS) vertical-external-cavity surface-emitting laser (VECSEL). Using diode laser pump, an OPS-VECSEL laser with a strain-compensated InGaAs-GaAsP-GaAs multiquantum-well (MQW) structure operated continuous-wave (CW) near /spl lambda//spl sim/1004 nm with record output power of 0.69 W in a TEM/sub 11/ mode, 0.52 W in a TEM/sub 00/ mode, and 0.37 W coupled to a single-mode fiber. It is feasible to produce greater than 1 W of power in a diffraction-limited circular beam from an efficient, compact, manufacturable and reliable OPS-VECSEL laser.     

High-speed Modulation of InGaAs: Sb-GaAs-GaAsP quantum-well vertical-cavity surface-emitting lasers with 1.27-/spl mu/m emission wavelength

1.27-/spl mu/m InGaAs: Sb-GaAs-GaAsP vertical-cavity surface-emitting lasers (VCSELs) were grown by metal-organic chemical vapor deposition and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than /spl sim/35% as the temperature raised from room temperature to 70/spl deg/C. With a bias current of only 5 mA, the 3-dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10-Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of /spl sim/5.25 GHz/(mA)/sup 1/2/. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25/spl deg/C to 70/spl deg/C.     

Independently addressable InGaAs/GaAs vertical-cavity surface-emitting laser arrays

The fabrication of an 8*8 independently addressable InGaAs/GaAs vertical-cavity surface-emitting laser array based on planar ion-implantation processes is described. The uniformity of laser characteristics across the array under both pulsed and CW operation is discussed. Simultaneous addressing of multiple lasers is demonstrated.<>     

Calculation of differential gain and linewidth enhancement factorin 980-nm InGaAs vertical cavity surface-emitting lasers

The optimization of differential gain and linewidth enhancement factor within VCSEL's is required to achieve improved performance under dynamic conditions. In this paper, the differential gain and linewidth enhancement factor in an InGaAs-GaAs VCSEL have been calculated over a range of carrier densities and at various wavelengths across the gain spectrum. The results show the importance of low threshold gain values in achieving high differential gain/low linewidth enhancement factor. By temperature tuning the lasing wavelength to shorter wavelengths than the gain peak, values of α_H as low as 0.6 can be achieved     

Mid-IR vertical-cavity surface-emitting lasers

We theoretically investigate the feasibility and potential performance of optically and electrically pumped vertical-cavity surface-emitting lasers (VCSELs) emitting in the mid-IR spectral region. Our model includes spontaneous, stimulated, and nonradiative recombination, numerical dispersion relations and optical matrix elements from a multiband finite-element algorithm, carrier and lattice heating, three-dimensional heat flow, electrical injection, photon propagation, and diffraction. Each modeled structure consists of a distributed Bragg reflector (DBR) semiconductor bottom mirror, a λ, 2λ, or 3λ optical cavity incorporating the type-II active region, and a dielectric top mirror through which the output beam is emitted. The optically pumped VCSEL structure with a 10-μm-diameter spot is predicted to operate up to a heat-sink temperature of 250 K and to be capable of producing >2 mW of CW output power. Furthermore, by collimating the pump beam with a microlens array, gain-guided VCSEL arrays with output powers in the watt range should be attainable. Comparable powers and operating temperatures are predicted for patterned devices with electrical injection through annular contacts. By far the most attractive properties are expected for structures employing a type-II interband cascade active region with electron recycling. The simulation predicts single-element threshold currents of 150 μA at 200 K and 1.1 mA at 300 K and CW output powers of 4.7 and 1.2 mW, respectively     

High-power etched-facet lasers

We demonstrate, for the first time, laser diodes with anetched facet fabricated by chemically assisted ion beametching, producing 1?7 W pulsed and 470mW CW output power from one facet. The devices were coated and bonded junction-side-up and tested at room temperature. The single 40 ?m stripe, 300 ?m-long devices exhibit 94 mA threshold current and differential quantum efficiencies of 80% pulsed (78% CW).     

Vertical-external-cavity surface-emitting lasers and quantum dot lasers

The use of cavity to manipulate photon emission of quantum dots (QDs) has been opening unprecedented opportunities for realizing quantum functional nanophotonic devices and quantum information devices....     

Tapered waveguide InGaAs/InGaAsP multiple-quantum-well lasers

The use of ultrathin etch-stop techniques to expand the vertical optical mode size adiabatically in 1.5-μm InGaAs/InGaAsP MQW lasers using a tapered-core passive intracavity waveguide structure is discussed. 30% differential quantum efficiency out the tapered facet, far-field FWHM of ~12° and a butt-coupling efficiency into a cleaved fiber of -4.2 dB, with -1-dB alignment tolerances of ~±3 μm, were achieved     

Vertical-cavity surface-emitting laser monolithically integratedwith intracavity monitor diode with temperature-insensitive responsivity

An intracavity monitor diode with QW-absorber is integrated within the bottom Bragg reflector of an 850 nm VCSEL. Temperature-insensitive responsivities are obtained by adopting a suitable QW design for the absorber. The thermal dependence of the remaining photocurrent offset due to spontaneous emission can be minimised by a proper choice of laser detuning and position of the absorber QW inside the Bragg reflector     

长波长GaInNAs垂直腔面发射激光器

新出现的直接跃迁GaInNAs与具有高反射率的AlAs／GaAs分布布拉格反射镜相结合构成了GaAs基长波长(1．3—1．6μm)垂直腔面发射激光器(VCSEL)，将成为光纤通信、光互联和光信息处理等的关键元件。本文从材料的选取、外延技术和GaInNAs VCSEL国外和国内的发展状况等方面对长波长GaInNAs VCSEL进行了综合阐述。     

GaInAsP/InP surface-emitting lasers with current confining structure

In order to reduce the threshold current of GaInAsP/InP surface-emitting (SE) lasers, we search for an effective current confining structure and examined several types; round-low-mesa, round-high-mesa/polyimide-buried, buried-heterostructure (BH), and planar-buried-heterostructure (PBH). The minimum threshold current was reduced down to 18 mA at 77 K and the threshold current density was estimated to be reduced to 3 kA/cm². The operating temperature has been raised to -10°C (263 K). The longitudinal-mode hopping was first observed for GaInAsP/InP SE lasers. The effective refractive index for GaInAsP/InP SE lasers was 4-5, that was almost the same as conventional edge-emitting lasers.