Quantum cascade lasers as metrological tools for space optics
Authors: Bartalini S., Borri S., Galli I., Mazzotti D., Cancio P., Giusfredi G., De Natale P.
Autors Affiliation: Istituto Nazionale di Ottica Applicata (INOA) – CNR, IT-50125 Firenze, Italy; European Laboratory for Non-Linear Spectroscopy (LENS), IT-50019 Sesto Fiorentino, Italy; Dipartimento di Fisica, Università degli Studi di Firenze, IT-50019 Sesto Fiorentino, Italy
Abstract: A distributed-feedback quantum-cascade laser working in the 4.3÷4.4 mm range has been frequency stabilized to the Lamb-dip center of a CO2 ro-vibrational transition by means of first-derivative locking to the saturated absorption signal, and its absolute frequency counted with a kHz-level precision and an overall uncertainty of 75 kHz. This has been made possible by an optical link between the QCL and a near-IR Optical Frequency Comb Synthesizer, thanks to a non-linear sum-frequency generation process with a fiber-amplified Nd:YAG laser. The implementation of a new spectroscopic technique, known as polarization spectroscopy, provides an improved signal for the locking loop, and will lead to a narrower laser emission and a drastic improvement in the frequency stability, that in principle is limited only by the stability of the optical frequency comb synthesizer (few parts in 1013).
These results confirm quantum cascade lasers as reliable sources not only for high-sensitivity, but also for highprecision measurements, ranking them as optimal laser sources for space applications.
Conference title: International Conference on Space Optics 2008 (ICSO 2008)
KeyWords: Locks (fasteners); Natural frequencies; Optical emission spectroscopy; Optical materials; Quantum cascade lasers; Semiconductor lasers; Space applications, Distributed feedback; High-precision measurement; Optical frequency combs; Polarization spectroscopy; Saturated absorptions; Spectroscopic technique; Sum frequency generation; Vibrational transitions, Neodymium lasersDOI: 10.1117/12.2308288