SESAM Q-Switched 1534 nm Microchip Lasers: Pulse Duration, Repetition Rate, and Peak-Power Optimization for LIDAR Application

Abstract

Q-switched 1.5 μm Er,Yb-doped microchip lasers are a particularly interesting class of lasers [1]-[4] due to their monolithic design, small footprint, 976 nm diode pumping, on-board mass-producible architecture, and high pulse energy· enabled by the long upper-state lifetime of the gain material. Recently· the interest in these lasers has increased significantly due to the need for eye-safe LIDAR for drones, UAVs, rovers and autonomous cars. Various LIDAR applications have very different requirements for the pulse repetition rate, pulse energy, peak power and pulse width. In this work, we have explored the borders for the combination of these parameters by tailoring the properties of the Q-switching element, which is an InP-based semiconductor saturable absorber mirror (SESAM). In particular, we have put an emphasis for obtaining 10–100 kHz repetition rate in combination with 1–3 ns pulse width and preferably over 1 kW peak power. This set of target parameters was chosen as it could provide a reasonable compromise between positioning accuracy, speed of measurement and detectability of the signal. It should be noted, that simple, low-cost devices fulfilling these pulse specifications are currently not widely commercially available.