Structural color filters with compensated angle-dependent shifts.

Structural color filters use nano-sized elements to selectively transmit incident light, offering a scalable, economical, and environmentally friendly alternative to traditional pigment- and dye-based color filters. However, their structural nature makes their optical response prone to spectral shifts whenever the angle of incidence varies. We address this issue by introducing a conformal VO2 layer onto bare aluminum structural color filters. The insulator-metal transition of VO2 compensated the spectral shift of the filter's transmission at a 15° tilt with 80% efficiency. Unlike solutions that require adjustment of the filter's geometry, this method is versatile and suitable also for existing structural filters. Our findings also establish tunable materials in general as a possible solution for angle-dependent spectral shifts.

Experimental demonstration of magnetoplasmon polariton at InSb(InAs)/dielectric interface for terahertz sensor application.

We experimentally demonstrate surface plasmon resonance (SPR) in the terahertz range in InSb and InAs. The surface plasmon is excited on the interface between a thin polymer film and the semiconductor using a silicon prism in Otto configuration. The low effective mass of InSb and InAs permits tuning of the SPR by an external magnetic field in the transversal configuration. The data show a good agreement with a model. Strong excitation of the surface plasmon is present in both materials, with a shifting of resonance position by more than 100 GHz for the field of 0.25 T, to both higher and lower energies with opposite orientation of the magnetic field. Applicability of the terahertz SPR sensor is discussed, along with modeled design for the Kretschmann configuration.