Electrically tunable surface micromachined Fabry–Perot interferometer for visible light

We present a new kind of electrostatically tunable surface micromachined Fabry–Perot interferometer (FPI) structure and a process flow which was successfully used to fabricate devices for visible wavelength range. The novel fabrication process is based on using polymeric sacrificial layer. Fabricated devices have five-layer dielectric mirrors made of atomic layer deposited Al2O3 and TiO2 thin films. An AC voltage control together with integrated series capacitance simplifies the fabrication process and enables extension of the tuning range of the FPI. The FWHM (full width at half maximum) of the 5th order transmission is 5.4 nm with maximum transmission being about 67% at λ = 510 nm. The maximum transmission was limited by widening of the transmission peaks due to bending of the mirrors.