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A Suspended Metamaterial Mirror for Hyperspectral Shortwave Infrared Fabry-Perot Filters.
- Source :
-
Journal of Microelectromechanical Systems . Aug2022, Vol. 31 Issue 4, p644-652. 9p. - Publication Year :
- 2022
-
Abstract
- This paper reports the development of a broadband highly reflective and structurally flat large-area 2-D subwavelength grating (SWG) reflector, based on a tensioned single-layer silicon metamaterial membrane. Rigorous coupled-wave analysis is adopted to design the metamaterial reflector, resulting in a wavelength range of 600 nm (1.9- $2.5~\mu \text{m}$) with >99% reflectivity, which represents the largest reported fractional bandwidth $\Delta \lambda /\lambda _{\mathrm {c}}$ of 27%. Effects of design parameter deviations on the SWG reflector reflectivity are studied, showing that the reflector design has good fabrication tolerances. A freestanding 2-mm dimension 2-D SWG reflector has been fabricated with high precision, and optical measurements indicate polarization-independent average reflectivity of 99% over the wavelength range of 1.91- $2.49~\mu \text{m}$ , which agrees well with the modeled result. This paper also, for the first time, examines the surface flatness characteristics of a suspended single-layer 2-D SWG reflector. With a tensile stress of 10 ± 5 MPa in the silicon grating membrane, the freestanding reflector achieves nanometer-scale surface flatness, which provides a significant advantage over multilayer DBRs requiring stress-balancing. Furthermore, a hyperspectral Fabry-Perot shortwave infrared filter based on a top suspended 2-D SWG reflector and a bottom 4-pair Si/SiO2 distributed Bragg reflector (DBR) has been experimentally demonstrated for the first time. The filter is measured to have a peak transmission of 80% with a narrow full-width at half-maximum (FWHM) of about 4 nm. This spectral resolution is one order of magnitude higher than that of other reported MEMS/DBR-based Fabry-Perot filters and is well-suited to highly demanding hyperspectral shortwave infrared imaging applications. [2022-0060] [ABSTRACT FROM AUTHOR]
- Subjects :
- *METAMATERIALS
*INFRARED imaging
*OPTICAL measurements
*MIRRORS
*OPTICAL reflectors
Subjects
Details
- Language :
- English
- ISSN :
- 10577157
- Volume :
- 31
- Issue :
- 4
- Database :
- Academic Search Index
- Journal :
- Journal of Microelectromechanical Systems
- Publication Type :
- Academic Journal
- Accession number :
- 158333481
- Full Text :
- https://doi.org/10.1109/JMEMS.2022.3180701