A novel method is proposed to detect the horizontal shift of a specific nanoblock relative to a reference nanoblock using surface plasmon modes at nanometer resolution. To accomplish this task, two orthogonal localized surface plasmon resonances were excited within the air gap region between the silver nanoblocks at the respective wavelengths, 890 nm, and 1100 nm. This technique utilized the scattering far-field intensities of the two block nanostructures at the two specific wavelengths at two specific directional spots. The ratio of the scattering intensities at the two spots changed according to the horizontal shift of the block that moved. Correspondingly, this ratio can be used to provide the precise location of the block. This method can be applied to many fields, including label-free bio-sensing, bio-analysis and alignment during nano-fabrication, owing to the high resolution and simplicity of the process.

In this study, we propose a multi-color detector using a simple plasmonic metamaterial structure consisting of a silver and a indium phosphide. The color detector is composed of a metal strip with a periodicity in the x-axis direction on a layer of the dielectric material located on a metal substrate. This color detector can control the spectrum absorbed in the dielectric material layer by changing the thickness of the dielectric material layer or the width of the metal strip. The triangle formed by the three primary colors, namely, red, green, and blue, which are representatively detected by optimizing the color detector using only silver and indium phosphide, covers 44% of the standard Red Green Blue (sRGB) region. Furthermore, the area of the triangle obtained by further optimization, such as changing the material to gold or gallium phosphide or changing the period of the metal stirp, can aid in the detection of a larger number of colors covering 108% of the sRGB area.

The development of an efficient silicon-based nanolight source is an important step for silicon-based photonic integrated circuits. We propose a high quality factor photonic crystal nanocavity consisting of silicon and silica, which can be used as a silicon-compatible nanolight source. We show that this cavity can effectively confine lights in a low-index silica layer with a high confinement factor of 0.25, in which rare-earth dopants can be embedded as gain materials. The cavity is optimized to have a high quality factor of 15,000 and a mode volume of 0.01 μm3, while the resonance has a wavelength of 1537 nm. We expect that the high confinement factor in the thin silica layer and the high quality factor of the proposed cavity enable the cavity to be a good candidate for silicon-compatible nanolight sources for use in nanolasers or light-emitting diodes in the telecommunication wavelength region.

Beam steering technology is crucial for radio frequency and infrared telecommunication signal processing. Microelectromechanical systems (MEMS) are typically used for beam steering in infrared optics-based fields but have slow operational speeds. An alternative solution is to use tunable metasurfaces. Since graphene has gate-tunable optical properties, it is widely used in electrically tunable optical devices due to ultrathin physical thickness. We propose a tunable metasurface structure using graphene in a metal gap structure that can exhibit a fast-operating speed through bias control. The proposed structure can change beam steering and can focus immediately by controlling the Fermi energy distribution on the metasurface, thus overcoming the limitations of MEMS. The operation is numerically demonstrated through finite element method simulations.

Upconversion (UC) materials can be used to harvest near-infrared (NIR) light and convert it into visible light. Although this improves optical device operating spectral range and efficiency, e.g., solar cells, typical UC material conversion efficiency is too low for practical devices. We propose a cross-patterned slot waveguide constructed from UC material embedded in a high index semiconductor layer to improve UC. Since the slot waveguide mode is induced in the low index UC slot, NIR absorption (~970 nm) increased 25-fold compared with film structures. Furthermore, the spontaneous emission enhancement rate at 660 nm increased 9.6-fold compared to the reference film due to resonance excited in the UC slot (Purcell effect). Thus, the proposed UC slot array structure improved UC efficiency 240-fold considering absorption and emission enhancements. This double resonance UC improvement can be applied to practical optical devices.