We present a microfabricated grating whose period can be tuned in analog fashion to within a fraction of a nanometer. The tunable angular range is more than 400 μrad in the first diffracted order. The design concept consists of a diffractive grating defined onto a 400-nm membrane, with the membrane subsequently strained in the direction perpendicular to the grating grooves by thin-film piezoelectric actuation. The strain-tuned grating device was fabricated with microelectromechanical processes, utilizing both surface and bulk micromachining. The fabricated piezoelectric film achieved a measured dielectric constant of 1200. Device characterization yielded grating period changes up to 8.3 nm (0.21% strain in the membrane) at 10 V and a diffracted angular change of 486 μrad, in good agreement with the theory. Uniformity across the actuated grating and out-of-plane deflections are characterized and discussed.
© 2003 Optical Society of America
(010.1080) Atmospheric and oceanic optics : Active or adaptive optics
(050.1950) Diffraction and gratings : Diffraction gratings
(160.2260) Materials : Ferroelectrics
(230.3990) Optical devices : Micro-optical devices
Chee Wei Wong, Yongbae Jeon, George Barbastathis, and Sang-Gook Kim, "Analog Tunable Gratings Driven by Thin-Film Piezoelectric Microelectromechanical Actuators," Appl. Opt. 42, 621-626 (2003)