Far-field and near-field optical readings of under-50 nm-sized pits

Sumio Hosaka*, Toshimichi Shintani, Hajime Koyanagi, Keizo Katoh, Tetsuya Nishida, Toshiharu Saiki, Tsuyoshi Hasegawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)


In this study, we investigated the limitations of optical reading of very fine pits using conventional optics, immersion lens optics and near-field optics. Using very fine pits < 100 nm in size formed by electron beam writing, a reflection-type depolarization scanning near-field optical microscope (SNOM) read very fine pits < 50nm in size. On the other hand, far-field optics read fine pits only > 160 nm in size using a lens with a numerical aperture (NA) of 0.95 (17 Gb/in2). In addition, an oil immersion lens optics with a NA of 1.4 read fine pits only 100 nm in size (45 Gb/in2). Advanced near-field optics is a promising tool for achieving ultrahigh-density optical reading of trillion bits/in2.

Original languageEnglish
Pages (from-to)L884-L886
JournalJapanese Journal of Applied Physics, Part 2: Letters
Issue number8 A
Publication statusPublished - 2002 Aug 1
Externally publishedYes


  • Depolarization
  • Near-field optical reading
  • Near-field optics
  • SIL
  • SNOM
  • Tera-bit storage

ASJC Scopus subject areas

  • General Engineering
  • General Physics and Astronomy


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