Laser micromachining of acoustic chambers for optical microphones

Abstract Microphones are essential for voice and sound recognition, yet their dynamic range remains limited compared to the human. This challenge is being addressed by developing an optical microphone based on a vertical external cavity surface-emitting laser (VECSEL). In this work the design and fabrication process of a miniaturized acoustic chamber for such a microphone, using selective laser-induced etching (SLE) in fused silica, is presented. The chamber integrates key functionalities, including precise alignment markers, optical fiber coupling, and thermal and electrical interfaces. The SLE process enables high-resolution 3D microstructuring, supporting compact integration of optical and mechanical components. Experimental results confirm efficient optical coupling and robust structural performance, demonstrating the potential of laser micromachining for next-generation opto-acoustic sensors.