Mid-Infrared and THz Spectroscopy: Innovative Tools and Applications

Dear Colleagues,

One of the most challenging struggles in photonics in recent decades has been the realization of high-performance infrared spectrometers, in particular in the mid-infrared (mid-IR) and THz ranges of the electromagnetic spectrum. In fact, these regions are crucial for gas-phase laser spectroscopy: in the mid-IR the linestrength of absorption lines is generally larger with respect to the near-infrared, while Doppler linewidths linearly decrease with increasing wavelength. This becomes even more important in the THz range, where molecular spectroscopy has proven an amazing scientific potential.

In these two spectral domains, many chemical species have very strong characteristic vibrational, rotational, and ro-vibrational transitions, which why they are commonly addressed as molecular fingerprint regions. The laser spectroscopy of molecular gas samples is playing a significant role both in attractive fundamental research (i.e., time variation of fundamental constants, the search for hypothetical long-range fifth forces between hadrons, detection of parity violation, test of quantum electro-dynamics models) and in real-world applications, spanning from environmental monitoring to health care, from food adulteration testing to homeland security.

The present Special Issue is dedicated to state-of-the-art laser spectrometers in the mid-IR and THz range, including smart techniques and new theoretical and experimental approaches for gas-phase molecular spectroscopy. Particular interest will be given to innovative tools for spectroscopy in such spectral regions, including but not limited to emerging photonic technologies, novel and improved sources, non-linear crystals, supercontinuum sources, waveguides, resonators, hollow core fibers, novel and improved detectors, high-performance resonant cavities, electro-optic devices, and metamaterials. Finally, a focal point will be the latest advances in mid-IR and THz frequency metrology, by using consolidated or emerging frequency comb synthesizers (i.e., microresonators, quantum cascade lasers, or quadratic combs).

Dr. Mario Siciliani de Cumis
Dr. Luigi Consolino
Guest Editors

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• mid-IR and THz spectroscopic techniques
• mid-IR and THz sources
• mid-IR and THz detectors
• frequency combs
• hollow core fibers
• non-linear crystals
• mid-IR and THz waveguides
• mid-IR and THz devices
• microresonators
• dual comb spectroscopy