High Data Transfer Rate and High Density Optical Disk Head

Abstract

Writing and reading probes with much higher optical efficiency than conventional fiber probes for high density optical disk system are described. In order to get smaller beam waist size than that due to the diffraction limit using conventional beam collecting devices, semiconductor materials of high refractive index are adopted as a prism type probe, of which top is flat cut. The diameter of the cutting area is a little larger than a half wavelength in the material. In the case of the GaP prism probe, the half wavelength is about 100 nm. After developing various fabrication processes, a prism like probe array with a flat cut tip has been prepared successfully, of which output window diameter is about 150 nm. Evaluation results of probe arrays using Scanning Near-field Optical Microscopy (SNOM) show that the laser beam emitted from flat-tip-probes hasthe diameter of about 150 nm and the throughput is also good enough to apply them to the high density optical disk system.