title: 5 μm laser source for frequency metrology based on difference frequency generation.
abstract: A narrow-linewidth cw 5 μm source based on difference frequency generation of a 1.3 μm quantum dot external cavity diode laser and a cw Nd:YAG laser in periodically poled MgO:LiNbO(3) has been developed and evaluated for spectroscopic applications. The source can be tuned to any frequency in the 5.09-5.13 μm range with an output power up to 0.1 mW, and in the 5.42-5.48 μm range with sub-microwatt output. The output frequency is stabilized and its value determined by measuring the frequency of the two lasers with a remotely located frequency comb. A frequency instability of less than 4 kHz for long integration times and a linewidth smaller than 700 kHz were obtained.
authors.affiliation: Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany. Ulf.Bressel@uni‐duesseldorf.de
authors.forename: Ulf
authors.initials: U
authors.lastname: Bressel
authors.forename: Ingo
authors.initials: I
authors.lastname: Ernsting
authors.forename: Stephan
authors.initials: S
authors.lastname: Schiller