Color imaging via nearest neighbor hole coupling in plasmonic color filters integrated onto a complementary metal-oxide semiconductor image sensor.

Abstract

State-of-the-art CMOS imagers are composed of very small pixels, so it is critical for plasmonic imaging to understand the optical response of finite-size hole arrays and their coupling efficiency to CMOS image sensor pixels. Here, we demonstrate that the transmission spectra of finite-size hole arrays can be accurately described by only accounting for up to the second nearest-neighbor scattering-absorption interactions of hole pairs, thus making hole arrays appealing for close-packed color filters for imaging applications. Using this model, we find that the peak transmission efficiency of a square-shaped hole array with a triangular lattice reaches ∼90% that of an infinite array at an extent of ∼6 × 6 μm(2), the smallest size array showing near-infinite array transmission properties. Finally, we experimentally validate our findings by investigating the transmission and imaging characteristics of a 360 × 320 pixel plasmonic color filter array composed of 5.6 × 5.6 μm(2) RGB color filters integrated onto a commercial black and white 1/2.8 in. CMOS image sensor, demonstrating full-color high resolution plasmonic imaging. Our results show good color fidelity with a 6-color-averaged color difference metric (ΔE) in the range of 16.6-19.3, after white balancing and color-matrix correcting raw images taken with f-numbers ranging from 1.8 to 16. The integrated peak filter transmission efficiencies are measured to be in the 50% range, with a FWHM of 200 nm for all three RGB filters, in good agreement with the spectral response of isolated unmounted color filters.