微透镜集成大功率垂直腔面发射激光器

High-Power and Microlens-Integrated Vertical Cavity Surface Emitting Lasers

为了改善大功率垂直腔面发射激光器(VCSEL)的模式特性,在GaAs衬底上采用限制扩散湿法刻蚀技术制作出了不同曲率半径的微透镜,与P型和N型分布式布拉格反射镜(DBR)构成复合腔结构,可以对腔内模式进行选择。有源区采用新型的发射波长为980 nm的InGaAs/GaAs应变量子阱,包括9对In_(0.2)Ga_(0.8)As(6 nm)/Ca_(0.18)As_(0.82)P(8 nm)量子阱.有源区直径100μm,微透镜直径300μm,曲率半径959.81μm,表面粗糙度13 nm。室温下,器件连续输出功率大于180 mW,阈值电流200 mA,远场发散角半角宽度分别为7.8°和8.4°,并且与没有微透镜的垂直腔面发射激光器输出特性进行了比较。

In order to improve the characteristics of the transverse mode of high-power vertical cavity surface emitting lasers （VCSELs）, microlens are used to realize high power and single transverse mode by forming a compound cavity with P-DBR and N-DBR of the VCSEL chip. Convex microlens is fabricated by one-step diffusion- limited wet-etching techniques on GaAs substrate. A novel material structure with nine In0.2 Ga0.8 As （6 nm）/Ga0.18As0.82 P（8 nm） quantum wells is employed to emit the wavelength of 980 nm. The diameter of the active layer is about 100μm, and the nominal diameter of the microlens is 300μm. The curvature radius of 959.81μm and the RMS of the whole microlens surface of 13 nm are obtained. The maximum output power is 180 mW in continuous-wave （CW） operation at room temperature. The far-field FWHM divergence angle θ∥and θ⊥ of the single device at a current of 1500 mA is 7.8°, 8.4°, respectively. The operation performance between microlens-integrated VCSEL and ordinary VCSEL is also discussed.