[KSCI] Korea Science Citation Index Service

http://dx.doi.org/10.3807/COPP.2020.4.5.428

Single-pixel Autofocus with Plasmonic Nanostructures

Seok, Godeun (Department of Electronics Engineering, Dong-A University)
Choi, Seunghwan (SE/Solution Business Unit, LUENSOFT INC.)
Kim, Yunkyung (Department of Electronics Engineering, Dong-A University)

Publication Information

Current Optics and Photonics / v.4, no.5, 2020 , pp. 428-433 More about this Journal

Abstract

Recently, the on-chip autofocus (AF) function has become essential to the CMOS image sensor. An auto-focus usually operates using phase detection of the photocurrent difference from a pair of AF pixels that have focused or defocused. However, the phase-detection method requires a pair of AF pixels for comparison of readout. Therefore, the pixel variation may reduce AF performance. In this paper, we propose a color-selective AF pixel with a plasmonic nanostructure in a 0.9 μ㎡ pixel. The suggested AF pixel requires one pixel for AF function. The plasmonic nanostructure uses metal-insulator-metal (MIM) stack arrays instead of a color filter (CF). The color filters are formed at the subwavelength, and they transmit the specific wavelength of light according to the stack period and incident angles. For the optical analysis of the pixel, a finite-difference time-domain (FDTD) simulation was conducted. The analysis showed that the MIM stack arrays in the pixels perform as an AF pixel. As the primary metric of AF performance, the resulting AF contrasts are 1.8 for the red pixels, 1.6 for green, and 1.5 blue. Based on the simulation results, we confirmed the autofocusing performance of the MIM stack arrays.

Keywords

Autofocus; CMOS image sensor; FDTD simulation; MIM;

Citations & Related Records

Times Cited By KSCI : 2 (Citation Analysis)

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