Scanning near-field optical microscope with a laser diode and nanometer-sized bit recording

We demonstrate 80 nm diameter bit recording for the first time using a phase change recording film and a reflection scanning near-field optical microscope with a 785 nm wavelength laser diode. The sample structure was a 20 nm thick ZnS-SiO 2 protection layer/30 nm thick Ge 2 Sb 2 Te 5 recording film/150 nm thick ZnS-SiO 2 protection layer/polycarbonate substrate. Writing was performed with pulsed laser light of 8.4 mW for 5 ms and 0.5 ms, and 8.0 mW for 5 ms. Written bits were observed in reflection by illuminating a small light of 0.2 mW. In this form of recording, a formation of phase change domains of about 50 nm in diameter is expected if the surface deformation is suppressed. Our results indicate the possibility to achieve an ultra-high recording density of more than 100 Gb in -2 .