High-brightness and high-speed vertical cavity surface-emitting laser arrays

Abstract

High-power vertical-cavity surface-emitting laser (VCSEL) arrays, which can serve as the light source in modem lidar and three-dimensional optical sensing systems, have recently attracted a lot of attention. In these types of systems, the time-of-flight (ToF) technique, based on the round-trip time of short optical pulses is usually adopted. Further enhancement of the ranging distance and depth resolution in these ToF driven systems by the incorporation of a VCSEL array with a high available power, high brightness (narrow divergence angle), and fast response time is highly deskable. However, a large number of light emission apertures (several hundreds) in the VCSEL array is usually necessary to raise the output power level to several watts. This leads to a large parasitic capacitance and the RC-limited bandwidth may become the dominant limiting factor of the speed of the high-power VCSEL array. In this work, Zn-diffusion and oxide-relief apertures are used to manipulate the optical modes and reduce the parasitic capacitance, respectively, in a unit device for a 940 nm VCSEL array. The demonstrated VCSEL array has a quasi-single-mode output, high available power (4 W; 1% duty cycle), narrow divergence angle (similar to 14 degrees at 1/e(2)) under maximum output power, and a fast rise time (<100 ps). These results open up new possibilities for further enhancing the performance of ToF sensing systems at the 940 nm wavelength. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement