Design and analysis of high-temperature operating 795 nm VCSELs for chip-scale atomic clocks

Abstract

We propose a new structure design and analysis of high-temperature (>350 K) operating 795 nm vertical-cavity surface-emitting lasers (VCSELs) for 87Rb based chip-scale atomic clocks (CSACs). Compositions and thicknesses of the InAlGaAs/AlGaAs multiple quantum wells (MQWs) are optimized for high optical gain at elevated temperatures. The temperature sensitivity of the threshold current is estimated by calculating the temperature dependence of the cavity-mode gain. A self-consistent VCSEL model based on quasi-3D finite element analysis is employed to investigate the temperature distribution and output of the proposed structure. An output of 1 mW with a 3 dB bandwidth of 6 GHz is obtained from a 3 μm aperture VCSEL under 2.4 mA current at temperature higher than 340 K. These findings indicate that high-gain QWs and gain-offset consideration are especially crucial to make high-performance VCSELs at elevated temperatures.