Configurable optical retarder based on plasmonic grating integrated with bimorph actuator

A configurable optical retarder based on an active plasmonic grating for visible wavelength is reported. Due to giant birefringence induced on a slit between gold grating lines, a half-wave plate can be developed with a subwavelength thickness. In this research, the grating consists of Au/Si bimorph beams and by actuating interleaved beams by Joule heating, effective thickness of slits is adjusted, then the retardation is configured. From an electromagnetic field analysis, it is found that the retardation can be modulated from 330 to 90 degrees. Structural birefringence of the grating is demonstrated.