The enhanced transmission through periodic arrays of sub-wavelength holes in optically-thick metallic films has many potential applications, such as in wavelength filters, light extraction from light emission diodes, and subwavelength photolithography. A color filter comprising arrays of subwavelength holes in an aluminum film has been fabricated. In addition to the simplicity of the process, the aluminum film enables the excitation of visible-range surface plasmons due to its high plasma frequency. Periodic nanostructures in the aluminum film open the way for new visible color filters.

The reliability and small size of solid state scanners makes them ideal for LIDAR. We fabricated and demonstrated the successful operation of an optical scanner using silicon photonics integrated circuit technology. The scanner comprises a ring resonator multiplexer and a number of grating arrays, and employs a beam switching method, which means that the scanner is movement-free. The multiplexer determines the optical path and light is emitted from the selected grating. The scanning angle obtained was 6 degrees. LIDAR sensors can be used in automotive applications for automated cruising.

We propose two-photon absorption light-induced self-written (LISW) waveguide formation using short-wavelength infrared pulse laser light. It is suitable and efficient for single-mode optical interconnection, and also promising for small-core single-mode optical interconnection. The approach offers the possibility of not only decreasing the insertion loss, but also reducing the interconnection task time. We assessed this approach for single-mode optical interconnection. We obtained an LISW waveguide loss of about 0.06 dB for an LISW waveguide length of 100 μ m and a connection loss per facet of about 0.37 dB. We also presented the results on the interconnection between high-numerical-aperture small-core thermally-diffused expanded-core single-mode fibers having the mode field diameters of about 3 μm by using the same approach. The results showed the present approach to be a promising alternative route for efficient interconnection of small-core single-mode optical devices, such as silicon nanowires with appropriate configurations.

We measured the dynamical frictional force acting on highly oriented pyrolytic graphite and C${}_{60}$ substrates by a sliding Si${}_3$N${}_4$ tip as a function of sliding distance using the probe-tip–quartz-crystal-resonator technique. It was found that the dynamical frictional force undergoes a drastic change when the oscillation amplitude is approximately the lattice constant of each substrate: For a small case, it is directly proportional to the amplitude, while for a large case, it does not depend on the amplitude. The observed behavior is qualitatively understood by a simple one-dimensional Tomlinson model.

Imaging optics cannot focus light beams emitted from different points onto one point with a lens. Therefore, fabricating a 3D image sensor with a focal plane array is challenging. We developed an imaging optics device with an intentionally shifted focal plane switch array comprising pixels with two optical antennas, a switch, and a receiver on a chip. We successfully illuminated a single point, received the reflected light with the same pixel, and scanned an illuminating target. The proposed system can serve as a 3D image sensor, with a detection range of 204 m for Lambertian reflectors with 94% reflectivity, and as a beam combiner for high-power lasers.

We fabricated arrays of subwavelength slits in an Al film and measured their optical properties in the visible light region. Al crossbeams were installed as supports between the Al lines to enable us to precisely fabricate the nanoslits. Visible light polarized parallel to the slits transmits at shorter wavelengths, similar to that of a wire grid array at infrared wavelengths. On the other hand, for light polarized perpendicular to the slits, the transmission is at longer wavelengths and significant absorption takes place at shorter wavelengths due to Fano-type interference. This absorption in the visible wavelength region is due to the precise nanofabrication process and the high plasma frequency of Al. These results show that Al nanoslits can be used as polarization filters in the visible wavelength region.