大功率低阈值980nm单模AlGaInAs/AlGaAs量子阱激光器

To achieve low threshold current as well as high single mode output power,a graded index separate confinement heterostructure(GRIN-SCH)AlGaInAs/AlGaAs quantum well laser with an optimized ridge waveguide was fabricated.The threshold current was reduced to 8 mA.An output power of 76 mW was achieved at100 mA current at room temperature,with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3.The maximum single mode output power of the device reached as high as 450 mW.     

The simulation of thermal characteristics of 980 nm vertical cavity surface emitting lasers

In order to design a single mode 980 nm vertical cavity surface emitting laser (VCSEL),a 2μm output aperture is designed to guarantee the single mode output.The effects of different mesa sizes on the lattice temperature,the output power and the voltage are simulated under the condition of continuous working at room temperature,to obtain the optimum process parameters of mesa.It is obtained by results of the crosslight simulation software that the sizes of mesa radius are between 9.5 to 12.5μm,which cannot only obtain the maximum output power,but also improve the heat dissipation of the device.     

High power single mode 980 nm AIGalnAs/AIGaAs quantum well lasers with a very low threshold current

To achieve low threshold current as well as high single mode output power, a graded index separate confinement heterostructure （GRIN-SCH） A1GaInAs/A1GaAs quantum well laser with an optimized ridge wave- guide was fabricated. The threshold current was reduced to 8 mA. An output power of 76 mW was achieved at 100 mA current at room temperature, with a slope efficiency of 0.83 W/A and a horizon divergent angle of 6.3°. The maximum single mode output power of the device reached as high as 450 mW.     

980nm垂直腔面发射激光器线阵及其温度特性研究

A 980 nm bottom-emitting vertical-cavity surface-emitting laser linear array with high power density and a good beam property of Gaussian far-field distribution is reported. This array is composed of five linearly arranged elements with a 200 μm diameter one at the center, the other two 150μm and 100μm diameter ones at both sides of the center with center to center spacing of 300μm and 250μm, respectively. A power of 880 mW at a current of 4 A and a corresponding power density of up to 1 kW/cm^2 is obtained. The temperature dependent characteristics of the linear array are investigated. The thermal interaction between the individual elements of the VCSEL linear array is smaller due to its optimized element size and device spacing, which make it more suitable for high power applications. A peak power of over 20 W has been achieved in pulsed operation with a 60 ns pulse length and a repetition frequency of 1 kHz.     

Large Aperture Low Threshold Current 980 nm VCSELs Fabricated with Pulsed Anodic Oxidation

Pulsed anodic oxidation technique, a new way of forming current blocking layers, was successfully used in ridge-waveguide QW laser fabrication. This method was applied in 980 nm VCSELs fabrication to form a high-quality native oxide current blocking layer, which simplifies the device process. A significant reduction of threshold current and a distinguished device performance are achieved. The 500 μm diameter device has a current threshold as low as 0.48 W. The maximum CW operation output power at room tempe...     

X-Band GaN Power HEMTs with Power Density of 2.23W/mm Grown on Sapphire by MOCVD

The growth,fabrication,and characterization of 0.2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on (0001) sapphire substrates by MOCVD,are described.The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cm2/(V·s) at an electron concentration of 1.52e16cm-3.The resistivity of the thick GaN buffer layer is greater than 1e8Ω·cm at room temperature.The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω/□ with uniformity better than 96%.Devices of 0.2μm×40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of 77GHz.The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W (2.23W/mm) and a linear gain of 13.3dB at 8GHz.The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.     

High-power light-emitting diodes operating in the 1.9 to 2.1-µm spectral range

Light-emitting diodes (LED’s) operating in the spectral range 1.9–2.1 μm have been fabricated by liquid-phase epitaxy on the basis of AlGaAsSb/GaInAsSb double heterostructures with a high Al (64%) content in the wide-gap regions. The design of the LED makes it possible to locate the active region near the heat-removal elements of the housing, and pass the light through the GaSb substrate, which is completely unshielded by the contact. The LED’s are investigated in the quasi-continuous (CW) regime and pulsed regime at room temperature. The optical power of the LED’s possesses a linear current dependence over a wide range of currents. A CW optical power as high as 4.6 mW and a peak optical power of 190 mW in the pulsed regime were achieved at room temperature. It is shown that the transition from linear to sublinear current dependence of the optical power is governed by Auger recombination in the pulsed regime at pulse durations as low as 5 μs. Fiz. Tekh. Poluprovodn. 33, 239–242 (February 1999)     

Room temperature continuous wave operation of quantum cascade laser at λ～ 9.4μm

Continuous wave (CW) operation of long wave infrared (LWIR) quantum cascade lasers (QCLs) is achieved up to a temperature of 303 K.For room temperature CW operation,the wafer with 35 stages was processed into buried heterostructure lasers.For a 2-mm-long and 10-μm-wide laser with high-reflectivity (HR) coating on the rear facet,CW output power of 45 mW at 283 K and 9 mW at 303 K is obtained.The lasing wavelength is around 9.4μm locating in the LWIR spectrum range.     

Analysis and design of CW-LD pumped stable Q-switched laser

A high power continuous wave (CW) laser diode (LD) pumped acousto-optic Q-switched Nd:YVO4 laser is presented. A short pulse at the 1064 nm is obtained. With a repetition rate of 50 kHz, the maximum average output power of 5.72 W is achieved. The optical conversion efficiency and the slope efficiency are up to 28% and 32.4% respectively. At the repetition rate of 10 kHz and the pulse width of 16.3ns, the maximum single pulse energy of 286 μJ and the peak power of 13kW are acquired. The laser can be used as a signal source in the free-space optical communication. The output signal agrees with the modulate signal well.     

High efficiency, high power 808nm laser array and stacked arrays optimized for elevated temperature operation

Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or eonductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the h     

980nm大功率垂直腔底发射激光器

报道980nm大功率底发射垂直腔面发射激光器的结构、研制及器件的阈值电流、输出功率和光谱特性．在室温(24℃)下，5A连续电流工作时，出光孔径400μm的器件激射波长为984．1nm，输出功率达到1．42W，是目前所能见到报道中最高的．研究了出光孔径600μm的器件在连续工作时，激射波长、光谱半高宽随注入电流的变化以及在重复频率100Hz，脉冲宽度50—1000μs条件下的输出功率、效率与注入电流的关系．     

650-nm vertical-cavity surface-emitting lasers: laser properties and reliability investigations

650-nm AlGaInP-AlGaAs-based oxide-confined VCSELs are investigated in dependence on the current aperture size. VCSELs with small aperture (a=5 /spl mu/m) have a maximum continuous-wave (CW) output power of about 1 mW at room temperature. They reach higher operating temperatures (T/sub max/=55/spl deg/C), have narrower beam profiles, less transverse modes, and a higher side mode suppression compared to large aperture VCSELs (a>13 /spl mu/m). The latter devices emit a CW-output power P=3 mW at 20/spl deg/C. Reliability tests of 655-nm devices show at 20/spl deg/C an output power of P/spl ap/0.4 mW over more than 1000 h and at 40/spl deg/C P/spl ap/0.1 mW over 500 h.     

Monolithic VCSEL with InGaAsN active region emitting at 1.28 μmand CW output power exceeding 500 μW at room temperature

The authors report on electrically pumped MBE-grown VCSELs on GaAs substrate with an InGaAsN active region. Emitting above 1.28 μm with record characteristics. The CW output power at room temperature exceeds 500 μW with an initial slope efficiency of 0.17 W/A     

高功率窄脉冲垂直腔面发射激光器n-DBR反射率的优化

从理论上研究了n型分布布拉格反射镜(n-DBR)的反射率对器件阈值电流、输出功率以及转换效率的影响,得出了最佳反射率。在此基础上研制了垂直腔面反射激光器(VCSEL)单管和阵列器件,采用波形分析法对VCSEL器件的功率进行了测试。在脉冲宽度60ns,重复频率100Hz条件下,500μm口径单管器件在注入电流为110A时,峰值输出功率达102W,功率密度为52kW/cm2,4×4、5×5阵列器件在100A时,功率分别达到98W和103W。对比了单管器件在连续、准连续和脉冲工作条件下的输出特性和光谱特性,连续和准连续条件下激射波长的红移速率分别为0.92nm/A和0.3nm/A,6A时的内部温升分别为85℃和18℃,而脉冲条件下激射波长的红移速率仅为0.0167nm/A,6A时的温升为1.5℃,远小于连续和准连续的情况,这也是器件在脉冲条件下能得到很高输出功率的主要原因。     

High-power VCSEL arrays for emission in the watt regime at roomtemperature

Selectively oxidized InGaAs vertical-cavity surface emitting lasers (VCSELs) at an emission wavelength of λ=980 mm are investigated for high-power applications. Densely packed arrays consisting of 19 single devices with an active diameter of 50 μm emit 1.08 W of continuous-wave (CW) optical output power at room temperature. At 10°C, heat sink temperature the output power increases to 1.4 W, which corresponds to a chip size averaged power density of 1 kW·cm². Low divergence angle of less than 16° full-width at half-maximum (FWHM) and the circularly symmetric far-field pattern allow for simple focusing of the beam with power densities above 10 kW·cm²     

Electrically pumped room temperature CW VCSELs with 2.3 /spl mu/m emission wavelength

Continuous wave (CW) operation at room temperature of electrically pumped InGaAlAs/InP vertical-cavity surface-emitting lasers (VCSELs) at emission wavelengths as high as 2.3 /spl mu/m is demonstrated for the first time. Devices with 15 /spl mu/m active region diameter show a maximum output power of 0.75 mW at 20/spl deg/C and a maximum CW operating temperature of 45/spl deg/C.     

AlGaAs vertical-cavity surface-emitting laser responses to 4.5-MeV proton irradiation

We have irradiated single- and multimode AlGaAs vertical-cavity surface-emitting laser (VCSEL) arrays operating at a nominal wavelength of 780 nm with 4.5-MeV protons and doses ranging from 10 to 30 Mrad in the active region. We observed a peak power reduction of about 2% per Mrad in the 14-/spl mu/m aperture, multimode VCSELs. Single-mode VCSELs having an aperture of 6 /spl mu/m exhibited a smaller peak power reduction of 0.4%-1% per Mrad. A slight shift in the current threshold was observed only for the multimode VCSELs at dose levels above 10 Mrad. First results indicate a reduced VCSEL peak laser power output that is dominated by a temperature shift caused by the radiation induced increase in resistive heating. In contrast, the power reduction in edge-emitting lasers is dominated by the enhanced radiation induced nonradiative recombination rate. The VCSEL irradiation was performed with a focused ion micro beam that was rastered over the device surface, ensuring a very uniform exposure of a single device in the array.     

Single-Mode Emission From Vertical-Cavity Surface-Emitting Lasers With Low-Index Defects

Mode confinement to low-index "defect" regions of a two-dimensional square photonic lattice has been studied as a means to realize single-spatial-mode vertical-cavity surface-emitting lasers (VCSELs). A selective etching process with two-step metal-organic chemical vapor deposition is used to fabricate the low-index defect VCSELs. A device with a 9-mum-wide aperture demonstrates 2.9-mW continuous-wave (CW) output power. The near diffraction-limited single-lobe far-field and high-resolution spectral analyses confirm single fundamental defect mode emission. Comparison studies between pulsed and CW operation indicate that thermal effects have a significant impact on the modal performance of the devices. Single-mode emission with more than 8 mW of peak pulsed power has been observed with short pulsewidth operation (0.1 mus, 2%). Improvements in thermal management are required to achieve higher CW single-mode emission in these devices     

Performance characteristics of high-brightness, CW, diode laser arrays

Recently developed, high-brightness diode laser arrays have been tested at 50°C at output powers of 0.5 W CW and 1.0W CW from 100?m- and 200?m-wide active regions, respectively. The extrapolated lifetimes at room temperature exceed 40000 h. The maximum CW power output prior to catastrophic degradation of the facets is 2.0 W for the 100?m device and greater than 3 W for the 200?m-aperture device.