title: Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy.
abstract: We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250  cm(-1) within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000  cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Jin
authors.forename: Simona M
authors.initials: SM
authors.lastname: Cristescu
authors.forename: Frans J M
authors.initials: FJ
authors.lastname: Harren
authors.forename: Julien
authors.initials: J
authors.lastname: Mandon