Yuichi Kimura

Theory of Visible Light Emission from Scanning Tunneling Microscope

The mechanism for visible light emission from the scanning tunneling microscope (STM) has been investigated theoretically by adapting a theory for light emitting tunnel junctions (LETJ). From the analysis of the calculated results and available experimental data, the following picture emerges. The tunneling current first excites localized surface plasmons (LSP) that are localized in a region of a few tens of Angstroms between the STM tip-front and the sample surface. Some of them decay into surface plasmon polaritons (SPP) that propagate along the sample surface. There are two channels of light emission: one is direct emission from LSP and the other is emission through SPP. The relative branching ratio between these two channels depends on the experimental configuration. The effect of sample surface roughness is very small and negligible.

Colorless and polarization-independent polymer two-layered 4×4 optical switch for three-dimensional optical interconnection

We proposed a polymer 4×4 three-dimensional (3D) optical interconnection switch. The analysis shows colorless and polarization-independent operation. We fabricated the proposed device, and it successfully operated at 1550nm wavelength in quasi-colorless and polarization independence.

Polarization-independent and colorless switching operation of three-dimensional 4 - 4 polymer optical switch with two-layered waveguide structure

We fabricated a three-dimensional (3D) 4 × 4 polymer optical interconnection switch with a two-layered waveguide structure equipped with four Mach–Zehnder interferometer optical switches (MZ-OSs), two vertical directional couplers (VDCs), and a multimode interferometer (MMI) coupler. The experimental result for the device shows polarization-independent and colorless switching operation by the thermo-optic (TO) effect in the 1550-nm-wavelength range with a switching power of about 18 mW.