Advanced Optical Materials

Thermoreversible on–off recording using time-dependent, persistent phosphorescence is demonstrated in air at room temperature using an organic film composed of an aromatic guest, phenol derivative, and steroid host. Reversible aggregation of guest molecules controlled by thermal hysteresis triggers large reversible changes in their time-dependent room temperature phosphorescence.

Coaxial microcavities etched into the surface of a doped silicon substrate are shown to support localized surface plasmon resonances at terahertz frequencies. This provides a promising pathway for the development of terahertz devices with application in the areas of photonic integrated circuits, molecular sensing, and subwavelength imaging.

A simple method for the inscription of identical 20–30 nm features into single nanoparticles and their arrays is developed. Arrays of nanoparticles with exactly same optical properties can be used in nano-trapping including self-induced back-action trapping, Raman sensing, and metamaterial engineering.

Surface plasmon resonance (SPR) is excited on transparent oxide semiconductors “In₂O₃: Sn” in the near infrared range. Coupling between excitations of surface plasmons and molecular vibrations are demonstrated. The detection sensitivity of oxide-based SPR is close to that of gold-based SPR working in the visible range. These studies evidence the useful potential of oxide-based SPR in the NIR range for sensing applications.

Ultrasmall couplers for the excitation of plasmonic structures by photonic modes are presented. They are constructed by assembling point-like resonators in the near-field zone of the target structure. As a demonstration of its efficacy, this scheme is applied to unidirectional excitation of plasmonic waveguides. The overall footprint of the resulting coupling structures is less than λ²/10.