Feed-forward comb-assisted coherence transfer to a widely tunable DFB diode laser

• Published in: The Journal of chemical physics Vol. 149; no. 15; p. 154201
• Main Authors: Gotti, Riccardo, Sala, Tommaso, Prevedelli, Marco, Kassi, Samir, Marangoni, Marco, Romanini, Daniele
• Format: Journal Article
• Language: English
• Published: United States 21.10.2018
• ISSN: 1089-7690
• DOI: 10.1063/1.5046387

The transfer of phase coherence from an ultrastable master laser to a distributed feedback diode laser, using an optical comb as a transfer oscillator, is obtained via a new scheme allowing continuous scanning across the whole tuning range of the slave laser together with absolute frequency determination. This is accomplished without phase lock loops, through a robust high-bandwidth feed-forward control acting directly on the slave laser output radiation. The correction is obtained by means of a dual-parallel Mach-Zehnder interferometer used as an optical single-sideband modulator. Coherence transfer across a master-slave frequency gap of 14 THz yields an ∼10 kHz linewidth providing high injection efficiency of an optical cavity with finesse 250 000. This allows demonstrating a cavity ring-down absorption spectrum of low-pressure ambient air over a 300 GHz spectral window.