New designs of optical fiber probes for hybrid SNOM/STM

Ken Nakajima, Volker Jacobsen, Jaegeun Noh, Daisuke Fujita* and Masahiko Hara

Frontier Research System, RIKEN
*Nanomaterials Laboratory, National Institute for Materials Science

It is widely believed that the aperture size of an SNOM probe is a crucial factor of limiting its spatial resolution. As reported previously (K. Nakajima et al., Jpn. J. Appl. Phys., 38, 3949 (1999).), however, a doubly metal-coated sharpened optical fiber probe can be a promising alternative, where the metal was coated on the aperture to obtain a half-transparent conducting tip. It allowed us to use the probe as an STM probe simultaneously. Thus, an extremely small tip-sample gap distance could be achieved during an SNOM operation, resulting in a high-resolution feature (approximately 10 nm). In this presentation, we will report a recent progress on the fabrication process to improve the optical throughput that was sacrificed in our former process. The use of indium-tin-oxide and the doubly-tapered structure will be discussed extensively.