Precise frequency-difference measurement between the 1.66-μm transitions of methane

Kotaro Suzumura, Chikako Ishibashi, Hiroyuki Sasada

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


We determined 66 frequency differences (FD's) between rovibrational lines of methane at the 1.66-μm region. Following the technique developed by Nakagawa et al. [Opt. Lett. 20, 410 (1995)], we measured the FD's as the optical beat frequency between two external-cavity diode lasers locked at 1-MHz-wide saturated absorption dips of the methane lines. Even though the methane lines often overlap in Doppler-limited resolution, the spectrometer that we use resolves them and determines their FD's with better than 40-kHz precision. This fact demonstrates that the methane lines are promising candidates for frequency reference and that this technique has great potential for high-resolution molecular spectroscopy.

Original languageEnglish
Pages (from-to)1356-1358
Number of pages3
JournalOptics Letters
Issue number17
Publication statusPublished - 1997 Sept 1
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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