Acoustic speaker based on high-efficiency broadband nano-pillar photonic crystal Opto-thermo-mechanical MEMS excitation

This paper presents the first nanopillar membrane acoustic speaker, using nanoscale photonic crystal optical absorbers for thermo-mechanical excitation of speaker membrane. The acoustic emission could be measured using B&K Sound Pressure Level Meter, corresponding to sound pressure levels of 50-60 dB. Optical actuation for MEMS takes advantage of directly coupling of energy into selected device areas without any electrical interconnects as required in integrated electrostatic and piezoelectric actuation. In opto-thermo actuation, light incident onto the structures is absorbed and converted to heat via photon absorption. Here, we realized linear, high efficiency and broad-band optical actuation for circular Si/SiO₂ membrane resonator with integrated vertical silicon nano-pillar photonic crystal arrays.