title: Sub-Doppler resolution mid-infrared spectroscopy using a difference-frequency-generation source spectrally narrowed by laser linewidth transfer.
abstract: The spectral linewidth of a 3.28 μm difference-frequency-generation source has been reduced to 3.5 kHz using a laser linewidth transfer technique [Opt. Express21, 7891 (2013)]. We use an optical frequency comb with a broad servo bandwidth to transfer a narrow linewidth of a pump laser, a 1.06 μm Nd:YAG laser, to a signal laser, a 1.57 μm external-cavity laser diode. This source enables us to record the Lamb dip of the ν3 band R(2) E transition of methane with a molecular spectral linewidth of 21 kHz while the frequency axis is absolutely calibrated.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Sera
authors.forename: Masashi
authors.initials: M
authors.lastname: Abe
authors.forename: Kana
authors.initials: K
authors.lastname: Iwakuni
authors.forename: Sho
authors.initials: S
authors.lastname: Okubo
authors.forename: Hajime
authors.initials: H
authors.lastname: Inaba
authors.forename: Feng-Lei
authors.initials: FL
authors.lastname: Hong
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Sasada