We constructed a widely tunable spectrometer with sub-Doppler resolution and high sensitivity in the 1.66-μm region using a Fabry-Perot cavity as an absorption cell and a low-power extended-cavity laser diode as a light source. The light electric field is enhanced at the antinodes of the standing wave in the cavity cell, which enabled observation of saturated absorption spectra of the molecular overtone bands even though their transition dipole moments are small. The spectrometer sensitivity was drastically enhanced using a frequency modulation technique. The attained sensitivity allowed us to reduce sample gas pressure, optical power, and modulation amplitude, which resulted in a resolution of 320 kHz. We applied the spectrometer to precise frequency measurements of the 2ν3-band transitions of methane, and determined 66 frequency differences between them and two absolute frequencies with an accuracy of 40 and 600 kHz, respectively. We also recorded hyperfine-resolved spectrum of the 2ν4 band of methyl iodide, which gave unambiguous assignments.
|ジャーナル||Proceedings of SPIE - The International Society for Optical Engineering|
|出版ステータス||Published - 2001 1 1|
|イベント||Laser Frequency Stabilization, Satandards, Measurement, and Applications - San Jose, CA, United States|
継続期間: 2001 1 24 → 2001 1 26
ASJC Scopus subject areas
- コンピュータ サイエンスの応用