Thermally tunable optical aperture based on a segmented thin-film resonator

Apertures are basic elements which can be found in many optical systems. Since optical systems are continuously being miniaturized and integrated, there is a need for small and inexpensive apertures to control beam shape and light intensity. Current aperture concepts for the micrometer regime rely on moving MEMS lamella or controlling fluids by capillary or electrostatic forces. We demonstrate an aperture concept for single-wavelength operation based on thermal tuning of a segmented thin film resonator. Thermal tuning changes the optical thickness of the elastomer cavity. This allows for adjusting the intensity to any level between constructive and destructive interference in a specific aperture segment. In order to demonstrate aperture operation we simulate thermal, mechanical and optical properties using finite element method and transfer-matrix method. We confirm our simulation results by experimental beam shape measurements and spatially-resolved spectral transmission and light intensity measurements.

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