新型垂直腔面发射半导体激光器阵列

A Novel Vertical-cavity Surface-emitting Laser Array

设计出四次质子注入工艺制备垂直腔面发射激光器(VCSEL)阵列的方法,实现了对阵列中单元器件间的隔离以及对单元器件注入电流限制的分别作用。一方面通过对VCSEL外延片上分布布拉格反射镜(DBR)两次较浅的质子注入形成高电阻区域实现对阵列中单元器件间的隔离,另一方面通过再次的两次较深度的可以达到有源区上表面的质子注入形成高电阻区域实现对单元器件注入电流的限制。由瞬态热传导方程对阵列中单元器件间的热相互作用进行了理论分析。采用四次质子注入工艺实现了2×2、3×3简单的二维GaAs/A lGaAs量子阱VCSEL阵列,并对器件的激射近场、光谱特性及功率等进行了测量。

Vertical-cavity surface-emitting lasers （VCSELs） have obtained more attention over the past few years, due to many merits including high power, high efficiency coupling to fibers, high beam quality, ease to be integrated in arrays on single chip, and the low fabrication cost. Especially, high power VCSELs emitting at 850 - 980 nm are desired for optical communications, pumping solid-state lasers and Er- or Yb-doped optical amplifier. The proton implantation method is widely used in the VCSELs fabrication as a convenient and effective technology. The four-time proton implantation method is designed for fabrication of vertical-cavity surface-emitting laser array. This method can achieve the isolation between individual elements in arrays and current confinement in elements, respectively. Firstly, by using lower energy implantation on the top distributed Bragg reflectors to form the high resistance area＇s isolation between individual elements of the arrays ; secondly through the higher energy implantation onto the upper layer of the active layers to form the high resistance areas, the current confinements among the elements is confirmed. Through the analysis of the thermal interaction between individual elements in array devices, a simple theoretical model has been formed, and by using the transient thermal conduction function this kind of thermal interaction has also been studied. We calculated the thermal interaction efficient length in the different pulse durations. The one side thermal diffusion length, and the thermal interaction efficient length between two neighboring diodes in array were also obtained theoretically. In the experiment, through the four-time proton implantation method the 2 × 2 and 3 × 3 two-dimensional vertical-cavity surface-emitting laser array devices have been fabricated from the GaAs/AlGaAs multiple quantum well VCSEL epitaxial chips, and the characteristics such as near field, emission spectrum, and light output power have also been measured. From the measured lasing spectra results, there is no obvious difference in the lasing wavelength between element and array devices. For the light output power, the element device produces optical power of 2.66 mW, and it is up to 23.6 mW from the 3 × 3 VCSEL array device, which is almost the total sum of all elements in the array. Finally, We think that our study of the thermal interaction in 850 nm VCSEL array by using our thermal diffusion model could push the study of the thermal effect of VCSELs array device in other wavelength region.