High-power vertical-cavity surface-emitting laser (VCSEL) arrays, which can serve as the light source in modern lidar and 3-diemensional
(3-D) 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 desirable. However, a large number of light emission apertures (several hundreds) in the VCSEL array is
usually necessary to raise 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 (QSM) output, high available power (4W; 1% duty cycle), narrow divergence angle
(~140 at 1/e2) 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.