Shun Kamada

Design optimization and fabrication of Mach- Zehnder interferometer based on MIM plasmonic waveguides.

We proposed and designed a compact unbalanced Mach-Zehnder interferometer (MZI) based on metal/insulator/metal (MIM) plasmonic waveguides for ultrafast optical signal processing. The MZI was fabricated by a lithography technique and we provide, for the first time experimental evaluation of the transmission performance of the MZI using MIM PWGs. The experimental results were in good agreement with the numerical simulations. The proposed structure could be considered as a key device for on-chip optical integrated circuits.

Resonance modes in unbalanced Mach-Zehnder interferometers embedded in plasmonic waveguides

We proposed an unbalanced Mach-Zehnder interferometer (MZI) by using Metal/Insulator/Metal PWGs for optical modulation or sensor devises. Transmission spectra of the MZI were calculated by Finite difference time domain method. We observed an interference pattern and transmission dips in calculated transmission spectra of an unbalanced MZI. An interference pattern is due to different path length of an unbalanced MZI. The Transmission dips are due to resonance in unbalanced MZI. Standing wave was appeared when the wavelength of the gap plasmon mode is equal to the integral multiple of PWG length of resonance area. Therefore, an unbalanced MZI in plasmonic waveguides serves as a ring resonator.

Plasmon resonance sensors for compact plasmonic integrated device (Conference Presentation)

Surface plasmon polariton (SPP) provide the field enhancement and localization beyond the diffraction limit of light. By using SPP, we have numerically designed tiny resonance sensors as plasmonic integrated devices with silver or gold as metal material for near infrared region of light. We will present our recent work for the sensors. The sensors are the combination of the plasmon resonator and MIM channel plasmon waveguide with the gap of ~150 nm and the hight of ~1.5 micron. The typical area size of sensor is order of 1 square micrometers and their sensitivity for temperature or stress change is comparable to current optical sensors. We have fabricated some fundamental structure of the device by using the electron beam lithography and will show experimental optical characteristics for IR region.

Fabrication of peelable thin films containing crescent-shaped split-ring resonators for three-dimensional optical metamaterials

In this paper, we propose peelable thin films containing crescent shaped split-ring resonators (SRRs) that can be utilized for the fabrication of three-dimensional (3D) metamaterials. The SRRs were two-dimensionally fabricated by nanosphere lithography with closely packed polystyrene nanospheres in a large area prepared by electrostatic adsorption. The SRR monolayer film, which had macroscopic dimensions of over 10 × 10 mm2 (area) and a thickness of about 230 nm, was then obtained by using a separation technique. Once the SRR monolayer films were fabricated, multi-layered metamaterials were obtained via repetition of a simple stacking procedure. In this case, we fabricated a 4-layered SRR film with the same relative orientation for each layer. In order to investigate the optical characteristics of these multi-layered SRR films, transmission spectra for normal incident light were measured. The transmission spectra demonstrate that our multi-layered metamaterials operate in the near-infrared region.