Polarisation-Resolved Investigations of the Pico- and Nanosecond Dynamics of Broad Area Distributed Bragg Reflector Lasers under Very High-Current Pulse Excitation

Abstract

Diode lasers generating optical pulses with high peak power and pulse lengths in the pico- and nanosecond ranges are key components for LiDAR (Light Detection and Ranging) systems, e.g., for autonomous driving and object detection and other applications such as free-space communication, metrology, material processing and spectroscopy [1,2]. For automotive LiDAR systems short optical pulses (100 ps − 10 ns) with high pulse powers, low wavelength shift with temperature and good beam quality are needed [3,4]. To achieve this, we have developed and investigated distributed Bragg reflector (DBR) broad area (BA) lasers having an InGaAs single quantum well active region embedded non-centred in the AlGaAs confinement layer. The total cavity length is 6 mm, the DBR length 1 mm and the lateral aperture is defined by an etched mesa with a width of 60 μm. The vertical divergence is about 25° (FWHM) and the emission wavelength is 905 nm at 25°C. The laser diodes soldered p-side down on CuW submonts are mounted into a new in-house developed high-speed unit and are electrically driven by nearly rectangular shaped 1 ns to 10 ns long current pulses with very high amplitudes up to 120 A corresponding to a current density of about 40 kA/cm2 The aim of this contribution is to present for the first time experimental polarisation-resolved investigations of the complicated spatio-spectral-temporal behaviour of the laser emission under these high excitation conditions in the time range 100 ps − 10 ns.