We propose a plasmonic color filter consisting of a single aperture surrounded by concentric periodic corrugations for simultaneous imaging of a spectral range from the visible to the near-infrared. The incident light coupled with surface plasmons propagates through the sub-wavelength aperture as beaming light. The beaming light transmission is able to suppress the spatial color cross-talk between the pixels in an image sensor. We analyzed the transmission characteristics of a plasmonic color filter with periodic corrugations in a silver thin film by using the finite-difference time-domain algorithm. We demonstrated a multi-band transmission wavelength selectivity, of about 100 nm, for the spectral bandwidth ranging from visible to near-infrared. The simultaneous discrimination of visible and near-infrared light with a high color purity by the plasmonic color filter achieves both improved image recognition and smaller system-size compared with conventional systems, which is particularly important for applications such as vehicle-mounted cameras, security, and biological tissue engineering.

We demonstrate the multiband color filtering of a standard RGB color and a complementary CMY color by a plasmonic color filter, composed of concentric corrugated metallic thin film rings. The surface plasmon resonance is excited by the periodic corrugation, and the coupled light is transmitted through the central subwavelength aperture. Color selectivity is achieved not only in the visible but also in the near-infrared (NIR) region. Therefore, simultaneous imaging with visible and NIR can be realized by the integration of plasmonic color filters with sensors. We investigate the angle of incidence dependence of the transmission color selectivity and the color purity of the fabricated plasmonic color filter array.

We propose a plasmonic diffraction structure combined with deep trench isolation (DTI) filled with highly reflective metal to enhance the near-infrared (NIR) sensitivity of image sensors. The plasmonic diffraction structure has a silver grating on the light-illuminated surface of a typical silicon backside-illuminated CMOS image sensor. The structural parameters of the silver grating were investigated through simulations, and the mechanism of the NIR sensitivity enhancement was clarified. Under the quasi-resonant conditions of surface plasmon polaritons, incident NIR light effectively diffracted as a propagating light to the sensor silicon layer. The diffracted light travelled back and forth between the DTIs. The effective propagation length in silicon was extended to six times by silver-filled DTI, resulting in approximately five times improvement of the 3-µm-thick silicon absorption at a wavelength of 940 nm.

We experimentally demonstrated plasmonic color modulation by dynamically controlling the plasmon resonance excited in an assembled Ag nanocube (AgNC) monolayer. The plasmon resonance wavelength of the hybridization plasmon mode of the local plasmon and collective oscillation plasmon in the Ag nanocube monolayer is sensitive to the interparticle distances. The interparticle distances were continuously controlled with a stretchable and transparent polydimethylsiloxane (PDMS) substrate. Crystalline Ag nanocubes were synthesized through a polyol process. The nanocube shape provides a narrower plasmon resonance band as a result of the small dispersion of electron vibrations. The synthesized nanocubes were densely assembled in a monolayer on the PDMS substrate using the Langmuir–Blodgett (LB) method. The interparticle distance of the Ag nanocube monolayer was controlled from 5.8 to 24.8 nm through biaxial stretching of the substrate from 0 to 20%. The transmitted light color of the Ag nanocube monolayer was actively tuned from magenta to orange to yellow by stretching the substrate up to 20% under random polarization incidence. This color modulation was generated by the plasmon resonance transition from the collective oscillation mode between particles to the local oscillation mode in the isolated nanocubes. Such a plasmonic color modulation is expected to enable a multispectral image sensor with compact and high light utilization efficiency.

We report on the utilization of Si in plasmonics research, specifically targeting deep ultraviolet (DUV) applications. By incorporating periodic submicron gratings on a Si surface, we demonstrate a photoconductive Si detector with significantly enhanced responsivity to DUV light, which is achieved via surface plasmon resonance (SPR). Notably, even without a metal, the detector exhibits improved responsivity only under TM-polarized light, supporting the interpretation that Si excites SPR. Our demonstration not only validates the effectiveness of Si plasmonics for enhancing photodetector performance but also introduces innovative techniques with potential applications in various research fields. Published by the American Physical Society 2025