III–V Compound semiconductor micromachined actuators for long resonator tunable fabry-pérot detectors

Modern telecommunication demands tunable detectors that are needed for optical demultiplexing of fibre-transmitted data. The receiver therefore consists of a wavelength-selective detector sensitive around 1550 nm. Since detectors for this wavelength are typically fabricated on gallium arsenide (GaAs) or indium phosphide (InP), a monolithic integration with the filter provides additional functionality and reduces coupling problems. This article presents a long-resonator Fabry-Perot filter that has been fabricated by bulk micromachining and can be tuned by deflection of one or both of the Bragg mirrors that are realized as floating membranes. Thermal actuation of the membrane yields mechanical sensitivities up to 153 nm mW −1 under vacuum conditions and 13 nm mW −1 under normal pressure. This is high enough to tune the free spectral range with less than 5 mW.