Movable guided-mode resonant grating filters by four bimorph actuators for wavelength selective dynamic reflection control

We fabricate a wavelength selective variable reflection filter driven by four bimorph actuators, which can control positions of the filter anywhere within an air gap. As the filter, a two-dimensional doubly periodic guided-mode resonant grating (GMRG) filter is employed for the first time. Two-dimensional GMRG filters are independent of polarization direction of an incident light, which are strongly desired in optical communications system. In the fabrication, electron beam lithography is used for patterning and fast atom beam etching and vaporized HF etching are carried out to form self-sustained structures. The device was fabricated successfully. The peak reflectivity of 82.8 % was obtained at a wavelength of 1508.75 nm, and the response time of approximately 50 msec was measured.