We demonstrate that microlensing can be used for detecting planets in binary stellar systems. This is possible because in the geometry of planetary binary systems where the planet orbits one of the binary component and the other binary star is located at a large distance, both planet and secondary companion produce perturbations at a common region around the planet-hosting binary star and thus the signatures of both planet and binary companion can be detected in the light curves of high-magnification lensing events. We find that identifying planets in binary systems is optimized when the secondary is located in a certain range which depends on the type of the planet. The proposed method can detect planets with masses down to one tenth of the Jupiter mass in binaries with separations <~ 100 AU. These ranges of planet mass and binary separation are not covered by other methods and thus microlensing would be able to make the planetary binary sample richer.Comment: 5 pages, two figures in JPG forma

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.

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.

High-quality factor dielectric microcavities like whispering-gallery-mode resonators can be widely applied in fields such as laser, optical sensor, switch, and filter. We propose the whispering-gallery-mode double-disk cavity comprising dielectric disks apart along the face of the disk. The electric field of each disk with opposite phases was excited; the emitted radiation field was annihilated by destructive interference. We numerically achieved a 5.67-fold enhancement in quality factor at the double-disk cavity with a radius, thickness, and gap distance of 850 nm, 220 nm, and 220 nm, respectively, compared to a single dielectric disk with the same structural conditions.

Photonic resonances in nanostructures have been exploited in reflective or transmission color filters, which can provide vivid colors. Metallic nanostructures have been widely studied to demonstrate a variety of color filters based on strong light interaction due to plasmonic resonances. However, because of the severe absorption loss of metal in visible light, dielectric nanoparticles having Mie resonances are a popular study focus in recent years to achieve vivid colors. In contrast to the behaviors of point-like electric dipole in metallic nanoparticle, the interplay of the electric and magnetic Mie resonances in dielectric nanoparticle enables a large degree of freedom in manipulating the directivity of light scattering, reflecting/transmitting color, and spontaneous emission rates. Here, we propose a color reflector based on an array of silicon nanoparticles that shows reflectance greater than 70% and vivid colors over the entire visible spectrum range, which covers sRGB color area. Viewing angle dependencies of the color and brightness are also investigated by calculating color-resolved far-field patterns, while exhibiting maintenance of the color and high reflectance over a broad viewing angle.