Abstract
In recent years, optical frequency combs with a frequency modulated output have attracted considerable attention. While first observed decades ago in externally modulated lasers, a whole class of semiconductor lasers has since been identified to spontaneously enter such a regime of self frequency modulation. The temporal properties of these sources are commonly measured indirectly via phase-resolved frequency domain measurements. In this work, they demonstrate an asynchronous optical sampling technique which operates directly in time domain.. On the basis of a mid-infrared quantum cascade laser frequency comb, both its instantaneous intensity and optical frequency are measured. The results confirm a quasi-constant intensity output alongside a close to linear frequency chirp, in accordance with phase-resolved spectral measurements. Contrary to previous works, stable phase-locking is achieved in a regime of positive intracavity dispersion resulting in an inversion of the observed frequency modulation. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000601544Publication status
publishedExternal links
Book title
17Journal / series
Laser & Photonics ReviewsVolume
Pages / Article No.
Publisher
Wiley-VCHSubject
frequency combs; frequency modulation; mid-infrared lasers; optical sampling; quantum cascade lasersOrganisational unit
03759 - Faist, Jérôme / Faist, Jérôme
02205 - FIRST-Lab / FIRST Center for Micro- and Nanoscience
Funding
176584 - High-resolution QCL frequency comb spectrometer for the detection of trace gases and their isotopes (SNF)
724344 - On Chip Terahertz Frequency Combs (EC)
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