Hyper-Selective Plasmonic Color Filters

TL;DR

This paper introduces multilayer slot-mode plasmonic filters with ultra-narrow transmission peaks under 20 nm, enabling high-resolution hyperspectral imaging in compact CMOS sensors.

Contribution

The design of 5-layer metal-insulator-metal-insulator-metal structures achieves narrow, tunable transmission peaks by suppressing spurious features through multi-mode interference.

Findings

Achieved FWHM as small as 17 nm in transmission spectra.

Systematic wavelength tunability across visible and near-infrared.

Potential for integration into hyperspectral imaging arrays.

Abstract

The subwavelength mode volumes of plasmonic filters are well matched to the small size of state-of-the-art active pixels (~ 1 {\mu}m) in CMOS image sensor arrays used in portable electronic devices. Typical plasmonic filters exhibit broad (> 100 nm) transmission bandwidths. Dramatically reducing the peak width of filter transmission spectra would allow for the realization of CMOS hyperspectral imaging arrays, which demand the FWHM of transmission peaks to be less than 30 nm. We find that the design of 5 layer metal-insulator-metal-insulator-metal structures gives rise to multi-mode interference phenomena that suppresses spurious transmission features gives rise to a single narrow transmission band with FWHM as small as 17 nm. The transmission peaks of these multilayer slot-mode plasmonic filters (MSPFs) can be systematically varied throughout the visible and near infrared spectrum, so the same basic structure can serve as a filter over a large range of wavelengths.