Vertical coupled-cavity microinterferometer on GaAs with deformable-membrane top mirror

Fabry-Perot microinterferometer is demonstrated that combines a GaAs-AlAs vertical cavity with a suspended movable membrane. Electrostatic displacement of the gold/silicon nitride membrane allows for broad and continuous wavelength tuning of the cavity resonance formed by the combination of the GaAs cavity and the air gap below the membrane. The device exhibits a 32-nm tuning range around the 920-nm center wavelength for 0-14 V applied bias and FWHM linewidths near 3 nm; this corresponds to membrane deflections of up to 0.27 μm. Such structures provide the foundation for wavelength selective photodiodes, light emitters, and lasers in which the active wavelength is under voltage control.