Tunable optical filters with nanostructured suspended gratings

Abstract

In this article, the authors report a kind of nanostructured suspended grating (NSG), whose grating beams are connected with narrow mechanical springs at the center. Using an electrostatic comb drive actuator, the period of the fabricated silicon NSG is tuned from 1.20to1.43μm. With the increase in grating period, experimental results reveal that the resonant interference wavelengths are increased, while the resonant interference peaks are decreased. The reflectance interference resonance is associated with a leaky-mode resonance. Theoretical simulations based on a rigorous coupled-wave method are carried out for comparison, from which the resonant interference wavelength shift induced by the tuning grating period can be predicted. It is believed that the NSG should have practical applications in micro-optical systems, such as tunable optical filters.