An integrated photoacoustic terahertz gas sensor

An on-chip gas detector that transduces absorbed terahertz light to a mechanical motion using photoacoustics is proposed. The silicon chip confines light in an optical cavity, wherein an acousto-mechanical cavity is housed. The concentration of a trace gas can be determined from the amplitude of a membrane's motion. The simulations presented predict a minimum detectable limit of 1 ppm of methanol for 1 mW of terahertz power and an integration time of 25 ms.