Hisao Ohsawa

Nanometric Scale Biosample Observation Using a Photon Scanning Tunneling Microscope

A T4 bacteriophage with a tail diameter of about 9 nm was observed for the first time in an atmospheric condition without a metal film coating, by means of a superresolution photon scanning tunneling microscope (PSTM) using a fiber probe. Fiber probes with cone angles of 25°-100° and their minimum curvature radii less than 10 nm were fabricated andthe angle variance was less than 0.5°. The normal resolution of such a PSTM was evaluated to be less than 1 nm, and the lateral resolution, limited by the curvature radius of the fiber probe, was estimated to be within 20 nm.

Phase-modulation technique for accumulated photon echo

A novel photon-echo technique based on the phase-modulation method has been developed that is applicable to the accumulated photon echo in scattering materials.

Femtosecond optical memory with an incoherent light source

The time resolution in the photon echo memory has been improved significantly by using a broadband incoherent light and the heterodyne detection of the photon echo. The time resolution has reached almost the limiting value which is determined by the inhomogeneous spectral width of the hole burning material. With the use of a digital optical delay line, the optical data has been retrieved with a high signal-to-noise ratio.