Single-beam recording and retrieving of sub-wavelength-size optical information in a photorefractive crystal using near-field scanning optical microscopy

Abstract

We suggest a way of photorefractive recording of sub-wavelength size optical information using the refractive index change induced by the single beam from the tapered fiber tip of the near-field scanning optical microscopy (NSOM). Data are recorded by the pure (without any change in the topography of the surface) refractive index change induced near the surface of photorefractive crystal by the light intensity distribution from the subwavelength-size fiber tip in NSOM. The size of index variation can be smaller than the size of wavelength since the distance between the tapered tip of NSOM and the crystal is about 10 nm. This can modify the transmission and collection characteristics of the light from the NSOM through the photorefractive crystal. Therefore, the characteristics of the reading beam depend on whether we previously exposed (recorded) the light from the tapered fiber tip or not and thus, the change in transmission or collection characteristics can be regarded as the on/off (binary) data.