Output Characteristics of Q-switched Solid-State Lasers Using Intracavity MEMS Micromirrors

The output behavior of a Nd:YAG solid-state laser actively Q-switched by a MEMS scanning micromirror is presented. Using a gold-coated micromirror, maximum average output powers of 50 mW and pulse durations as short as 120 ns were obtained with a dual beam output. This output pattern originates from a pulse emission when the micromirror is at an angle from the cavity axis. The temporal and spatial behavior of this laser was experimentally characterized and then modeled using a numerical simulation of the laser rate equations. Finally, prospects for power scaling this MEMS-based Q-switch technique are demonstrated using a dielectric-coated micromirror, which led to average output powers of up to 650 mW and pulse energies above 40 μJ.

I. Introduction

IN recent years, advances in silicon fabrication technology and in particular the development of multi-user silicon fabrication facilities have enabled the development of low-cost optical microelectromechanical systems (MEMS) for laser applications. Most notably, scanning micromirrors have been integrated inside solid-state laser cavities as active mechanical Q-switches, enabling the generation of cavity-limited pulse durations at average powers exceeding 100 mW [1] . Compared to more traditional active Q-switching techniques using acousto-optic modulators (AOM) or electro-optic modulators (EOM), this MEMS-based approach provides significant advantages in miniaturization, reduction of power-consumption and cost. This technique particularly benefits from recent intense developments in optical MEMS generating new directions in optics [2]. Finally, the possibility of developing MEMS micromirror arrays will enable multiple, individually controlled, beam emission from the same laser gain medium impacting many applications in defense, industry and biology.