复合型微通道热沉设计与制作技术研究

从大功率半导体激光器可靠性封装和应用考虑,利用商用有限元软件Abaqus与CFdesign对微通道热沉材料、结构进行优化设计,结合相应的制造工艺流程制备实用化复合型微通道热沉。微通道热沉尺寸为27 mm×10.8 mm×1.5 mm,并利用大功率半导体激光阵列器件对所制备热沉进行散热能力、封装产生的"微笑效应"进行了测试,复合微通道热沉热阻约0.3 K/W,"微笑"值远小于无氧铜微通道封装线阵列,可以控制在1μm以下。复合型微通道热沉能满足半导体激光阵列器件高功率集成输出的散热需求与硬焊料封装的可靠性要求。     

Experimental investigation of thermal crosstalk in a distributed feedback laser array

Thermal crosstalk between lasers in a distributed feedback laser array has been investigated by measuring the oscillating-wavelength shift. Between closely situated lasers, thermal crosstalk due to lateral heat spreading decreases proportionally to the inverse of the laser distance. Thermal crosstalk due to heating in the heat sink and stem becomes dominant between relatively distant ( approximately 300 mu m) lasers. A diamond heat sink reduces thermal crosstalk to about 1/3 compared to a silicon heat sink.<>     

CW operation of monolithic arrays of surface-emitting folded-cavityInGaAs/AlGaAs diode lasers

A monolithic 0.84-cm² two-dimensional array of surface-emitting folded-cavity InGaAs/AlGaAs diode lasers was mounted junction up on a W/Cu microchannel heatsink and evaluated under continuous-wave (CW) operating conditions. Each laser in the array contained two upward-deflecting internal-cavity 45° mirrors which were etched using chlorine ion-beam-assisted etching, and two top-surface facets. The CW threshold current densities of different sections of the array were ⩽223 A/cm², while effective CW differential quantum efficiencies were ⩾30%. A CW output power of over 40 W was obtained from the entire array, while a current-limited output power density of 84 W/cm² with an average temperature rise of ~30°C was obtained from a quarter of the array     

300 mW operation of a surface-emitting phase-locked array of diode lasers

The focused-ion-beam micromachining of an output coupler and a 45° turning mirror to form a surface-emitting, 10-element, phase-locked array of diode lasers is described. 330 mW optical power was emitted at the turning mirror in pulsed operation.     

Bottom-emitting VCSEL's for high-CW optical output power

Bottom-emitting vertical-cavity surface-emitting InGaAs MQW lasers operating in the 980-nm wavelength regime have been designed for high continuous-wave optical output power. Devices of 200-μm active diameter and optimized performance reach 350-mW maximum output power when mounted on a heat sink. 50-μm-size lasers produce 100 mW at 25% electrical to optical power conversion efficiency. Thermal properties and size dependent basic characteristics are investigated in detail     

Integrated output power detection for AlGaAs laser array

A linear array of closely spaced AlGaAs lasers is mounted on an Si heat sink. Schottky diode detectors formed on the same Si chip provide optical sensing and electrical feedback signals for output power stabilization of the individual laser elements. The performance of a typical pair of adjacent devices is tested showing that electrical and optical crosstalk between lasers is virtually eliminated.     

金刚石复合热沉面发射激光器面阵热特性研究

通过设计基于金刚石微槽结构的复合热沉,利用不同材料的热导率差异改变热流传导方向,以优化垂直腔面发射半导体激光器(VCSEL)面阵由于温度分布不均匀导致的中心热量堆积的问题,从而改善激光器面阵整体的输出功率,提高可靠性。基于有限元分析法建立三维热电耦合模型,研究了VCSEL面阵单元排布方式对激光器热串扰效应的影响,同时还研究分析了金刚石复合热沉中微槽形状和位置的变化对半导体激光器内部温度的影响,设计最优结构对激光器的出光性能做进一步优化。采用金刚石复合热沉后的垂直腔面发射激光器面阵,与传统金刚石热沉的封装结构相比,激光器发光单元的温度差值降低了29%,为大面积半导体激光器面阵的输出功率优化提供了新思路。     

High-power, 4 W pulsed, grating-coupled surface-emitting laser

AlGaAs surface-emitting lasers fabricated with second-order grating, distributed Bragg reflector regions for output coupling and feedback are demonstrated to operate at high output powers. Powers of 1.75 and 4 W pulsed are reported for single gain section and three gain section lasers.<>     

Design for high-power single-mode operation from 2-D surface-emitting ROW-DFB lasers

Stable single-mode single-lobe operation to high powers is predicted for two-dimensional surface-emitting lasers, if second-order distributed feedback/distributed Bragg reflector (DFB/DBR) gratings are preferentially placed in the elements of a resonant-optical-waveguide array. Beside their usual functions (i.e., feedback and outcoupling), the gratings act as an effective array-mode selector due to different interaction with the gratings of different array modes. The in-phase array mode is strongly favored to lase around its (lateral) resonance due to better field overlap with DFB region and lower interelement absorption loss than for nonresonant array modes. For 20-element arrays with 700/600 /spl mu/m DFB/DBR gratings, emitting at /spl lambda/=0.98 /spl mu/m, high (/spl sim/100 A/cm/sup 2/) intermodal discrimination /spl Delta/J/sub th/ is obtained. /spl Delta/J/sub th/ is enhanced to /spl sim/225 A/cm/sup 2/ by introducing free-carrier absorption in the array-interelement regions.     

CW operation of monolithic arrays of surface-emitting AlGaAs diodelasers with dry-etched vertical facets and parabolic deflecting mirrors

A monolithic two-dimensional array of surface-emitting AlGaAs diode lasers with dry-etched vertical facets and parabolic deflecting mirrors was mounted junction-side up on a W/Cu microchannel heatsink and evaluated under continuous-wave (CW) operating conditions. Both the facets and parabolic deflecting mirrors were etched using chlorine ion-beam-assisted etching. Threshold current densities of different sections of the array were consistently around 240 A/cm², and measured CW differential quantum efficiencies were in the 46-48% range. CW power densities as high as 148 W/cm² were achieved with an average temperature rise of less than 25°C in this junction-side-up configuration     

垂直腔面发射激光器

The development and application of vertical-cavity surface-emitting lasers (VCSELs) are summarized in this paper. The emphasis is focused on the high power single and 2-D arrays bottom-emitting VCSELs with a wavelength of 980nm. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture single devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance are discussed. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.32W at room temperature.     

Oxide-defined GaAs vertical-cavity surface-emitting lasers on Sisubstrates

By employing a reactive low-temperature wafer bonding technique, we have demonstrated oxide-defined 850 nm vertical-cavity surface-emitting lasers (VCSEL's) on Si substrates. Devices reach a differential quantum efficiency of 53% and a light output power of 7.1 mW under room temperature and continuous-wave operation without a heat sink     

Microchannel heat sinks for two-dimensional high-power-densitydiode laser arrays

The operation of a two-dimensional GaInAsP/InP diode laser array with CW power dissipation up to 500 W/cm² into a Si microchannel heat sink is discussed. The approximately 1×4-mm² laser array was used to characterize the heat sink, and the value of 0.040°C cm²/W was obtained for the thermal resistance per unit area. The extrapolated value for a 1-cm² heated area is 0.070°C cm²/W     

1300-nm horizontal-cavity surface-emitting BH-DFB lasers for uncooled operation

We present a novel type of 1300-nm horizontal-cavity surface-emitting buried heterostructure distributed feedback (DFB) lasers showing high optical output power and uncooled direct modulation capability of 7.5 Gb/s. These lasers can be fabricated and tested using on-wafer techniques only, so the overall fabrication costs are considerably lower than with conventional edge-emitting DFB lasers.     

列阵半导体激光器中热相互作用及改进技术的研究

从半导体激光器产生的热量在热沉中的扩散入手 ,对列阵单元器件间的热相互作用进行了分析 ,提出了该过程是通过热流的扩散而发生作用的观点。通过这一分析获得了确定列阵器件中单元器件间距的理论依据。对二维列阵中上、下层器件的热相互影响以及脉冲工作的占空比进行了讨论 ,并将结果应用到 1.55μm半导体激光列阵器件中。采用漏光波导结构的单元器件 ,实现了二维 2× 2 ,2× 4两种列阵 ,其脉冲输出峰值功率分别达到 7W和 11W。     

高功率轴快流CO2激光器激励源热沉结构优化设计

为了提高激励源的热稳定性,保证4kW轴快流CO₂激光器的光束质量,采用计算流体动力学的方法,理论分析了激光器激励源热沉的散热机理,对热流密度为106W/m2、面积为16cm2的激励源热沉结构进行了优化设计。结果表明,经过优化之后的热沉其表面的最高温度低于340K,完全能够满足激光器正常工作时激励源核心功率MOSFET对散热指标的要求;同时经过数值模拟得到了带凹槽微通道热沉的优化结构尺寸,分别是微通道凹槽间距P=0.6mm,微通道凹槽倾角θ=45°,微通道凹槽交错距离s=0.1mm,同时当雷诺数Re=546.9时,热沉有最优的散热效果,激光输出功率的稳定度可以控制在±2%以内。此研究为设计具有高效散热能力的微通道热沉提供了理论指导。     

The use of spatially ordered arrays of etched holes for fabrication of single-mode vertical-cavity surface-emitting lasers based on submonolayer InGaAs quantum dots

To suppress the generation of high-order modes in vertical-cavity surface-emitting lasers based on submonolayer InGaAs quantum dots, the method of formation of a spatially ordered array of etched holes in the upper distributed Bragg reflector was used. Single-mode vertical-cavity surface-emitting lasers for spectral region of 990 nm with current-aperture diameter of 20 μm, threshold current 0.9 mA, and maximum output power 3.8 mW at room temperature were demonstrated. Single-mode lasing with the coefficient of side-mode suppression in excess of 35 dB is retained in the entire range of pump currents. A decrease in the current oxide aperture to sizes that are close to those of the optical aperture brings about an increase in the external quantum efficiency; however, in this case, the transition to the multimode of lasing is observed at high pump currents.     

Spectral characteristics of vertical-cavity surface-emitting lasers with external optical feedback

The measurement of the effects of external optical feedback on the spectra of VCSELs (vertical-cavity surface-emitting lasers) is reported. It is surprising that VCSELs have a sensitivity to optical feedback comparable to that of conventional edge-emitting lasers such as DFBs despite their significantly different structures. This is because the extremely short cavity length of VCSELs negates the effects of their highly reflective output mirrors. As in edge-emitting lasers, VCSELs exhibit well-defined regimes of feedback effects in their spectra. Since optical isolators cannot be easily applied to VCSELs due to their array structure, these lasers may be most useful in applications which are not sensitive to the spectral qualities of the light source.<>     

A high-power Ka-band quasi-optical amplifier array

Results for a high-power Ka-band quasi-optical amplifier array are presented in this paper. The amplifier consists of a 45-element double-sided active array with a hard-horn feed. Excess heat is removed via a metal carrier integrated into the array with liquid cooling at the periphery. Each unit cell of the array consists of transmitting and receiving patch antennas, driver and power amplifier monolithic microwave integrated circuits on input and output layers, and a through-plate coaxial transition, which connects the input and output layers. An estimated 25 W is radiated when the amplifier is used as an antenna feed, otherwise 13 W is collected into waveguide. Experimental results and construction details are discussed     

Performance, uniformity, and yield of 850-nm VCSELs deposited by MOVPE

Vertical-cavity surface-emitting lasers (VCSELs) emitting near 850 nm and fabricated with the metal-organic vapor phase epitaxy (MOVPE) epitaxial growth technique and a planar proton implant process have been demonstrated with excellent performance, uniformity, and yield across a 3-in wafer. Four thousand lasers were tested on a three-inch-diameter wafer, with a yield of 99.8%. This translates into a yield of 94% for fully functional 34/spl times/1 arrays. The average threshold current, threshold voltage, and dynamic resistance at 10 mA operating current were 3.07 mA, 1.59 V, and 34 ohms, respectively. Uniformity of better than /spl plusmn/9% in threshold current, /spl plusmn/1% in threshold voltage, and /spl plusmn/1.5% in maximum optical output power across a 34-element array was demonstrated.