title: Omnidirectional color filters capitalizing on a nano-resonator of Ag-TiO2-Ag integrated with a phase compensating dielectric overlay.
abstract: We present a highly efficient omnidirectional color filter that takes advantage of an Ag-TiO2-Ag nano-resonator integrated with a phase-compensating TiO2 overlay. The dielectric overlay substantially improves the angular sensitivity by appropriately compensating for the phase pertaining to the structure and suppresses unwanted optical reflection so as to elevate the transmission efficiency. The filter is thoroughly designed, and it is analyzed in terms of its reflection, optical admittance, and phase shift, thereby highlighting the origin of the omnidirectional resonance leading to angle-invariant characteristics. The polarization dependence of the filter is explored, specifically with respect to the incident angle, by performing experiments as well as by providing the relevant theoretical explanation. We could succeed in demonstrating the omnidirectional resonance for the incident angles ranging to up to 70°, over which the center wavelength is shifted by below 3.5% and the peak transmission efficiency is slightly degraded from 69%. The proposed filters incorporate a simple multi-layered structure and are expected to be utilized as tri-color pixels for applications that include image sensors and display devices. These devices are expected to allow good scalability, not requiring complex lithographic processes.
authors: Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 139-701, South Korea.
authors: Chul-Soon
authors: CS
authors: Park
authors: Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 139-701, South Korea.
authors: Vivek Raj
authors: VR
authors: Shrestha
authors: Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 139-701, South Korea.
authors: Sang-Shin
authors: SS
authors: Lee
authors: Department of Electronic Engineering, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul 139-701, South Korea.
authors: Eun-Soo
authors: ES
authors: Kim
authors: Laser Physics Centre, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia.
authors: Duk-Yong
authors: DY
authors: Choi