High-speed readout using small near-field optical head module with horizontal light introduction through optical fiber

Near-field optics, a super-resolution technique, is expected for optical data storage with high recording density (E. Betzig et al., Appl. Phys. Lett. vol. 61, p. 142, 1992; S. Hosaka et al, Nanotechnology vol. 8, p. A58, 1997). Recently, near- field optical heads using sliders, which can keep the distance between an aperture and a medium surface in proximity, were proposed, and reading from 110-250 nm pattern at the speed of 1.5-7.5 MHz was demonstrated (H. Yoshikawa et al., Opt. Lett. vol. 25, p. 67, 2000; F. Issiki et al., Appl. Phys. Lett. vol. 76, p. 804, 2000; K.T. Yatsui et al., Opt. Lett. vol. 25, p. 1279, 2000). These optical heads use an objective lens above sliders separately, to introduce the focused light to the aperture. However, this large light introduction using the objective lens leads optical heads with actuators to be large. From this perspective, we had proposed a small near-field optical head module with miniaturized light introduction (K. Kato et al., Tech. Dig. ISOM2000, p. 188, 2000). In this paper, we fabricated the proposed optical head module with air-bearing surface, and high speed reading from 200 nm chromium pattern formed on an SiO₂ disk medium was demonstrated.