A high angular tolerance spectral filter was realized incorporating an etalon, which consists of a TiO<sub>2</sub> cavity sandwiched between a pair of Ag/Ge mirrors. The effective angle was substantially extended thanks to the cavity's high refractive index. The device was created by embedding a 313-nm thick TiO<sub>2</sub> film in 16-nm thick Ag/Ge films through sputtering, with the Ge layer alleviating the roughness and adhesion of the Ag layer. For normal incidence, the observed center wavelength and transmission were ~900 nm and ~60%, respectively; throughout the range of 50°, the relative wavelength shift and transmission variation amounted to only ~0.06 and ~4%, respectively.
© 2012 Optical Society of Korea
(230.5750) Optical devices : Resonators
(310.3915) Thin films : Metallic, opaque, and absorbing coatings
(310.6845) Thin films : Thin film devices and applications
(230.7408) Optical devices : Wavelength filtering devices
Original Manuscript: May 7, 2012
Revised Manuscript: June 18, 2012
Manuscript Accepted: June 18, 2012
Published: September 25, 2012
Tae-Hui Noh, Yeo-Taek Yoon, Sang-Shin Lee, Duk-Yong Choi, and Seung-Chan Lim, "Highly Angle-tolerant Spectral Filter Based on an Etalon Resonator Incorporating a High Index Cavity," J. Opt. Soc. Korea 16, 299-304 (2012)
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