Ultrafast mid-infrared laser systems

Femtosecond laser sources operating in the middle-infrared (mid-IR) spectral range with high- repetition rates are of upmost interest for a variety of applications ranging from ultrafast spectroscopy, high-resolution and broadband spectroscopy, quantum optics, frequency metrology and synthesis of mid-IR optical frequency combs. In the last years a great effort has been devoted to develop ultrashort laser pulse trains in the mid-IR at around 3 μm and beyond, where inorganic and organic molecules show their strongest absorption features associated with fundamental roto-vibrational transitions.
We present two different laser architectures to generate femtosecond pulse trains in the wavelength region from 2 to 3 μm: a bulk laser system based on a Kerr-lens mode-locked (KLM) Cr2+-doped ZnSe crystal able to sustain four-optical-cycle pulse trains at 2.4 μm with repetition frequencies higher than 150 MHz [1] and an all-fiber laser system based on a non-linear polarization evolution (NPE) mode-locked Dy-doped fluoride fiber that generates, for the first time, stable and self- starting pulses with a duration of 828 fs at 3.1 μm [2].

References
[1] Y. Wang, T. T. Fernandez, N. Coluccelli, A. Gambetta, P. Laporta, and G. Galzerano, "47-fs Kerr-lens mode-locked Cr:ZnSe laser with high spectral purity," Opt. Express 25, 25193-25200 (2017)
[2] Y. Wang, F. Jobin, S. Duval, V. Fortin, P. Laporta, M. Bernier, G. Galzerano, and R. Vallée, "Ultrafast Dy3+:fluoride fiber laser beyond 3 μm," Opt. Lett. 44, 395-398 (2019)