March 2023
Spotlight Summary by David Novoa
Femtosecond long-wave-infrared generation in hydrogen-filled hollow-core fiber
The availability of ultrafast sources of long-wave infrared light (LWIR, wavelengths from 8 to 15 μm) has the potential to revolutionize multiple disparate fields such as molecular fingerprinting spectroscopy or strong-field physics. Unfortunately, such spectral domain is very difficult to access owing to the opacity and high dispersion of most materials, as well as the lack of efficient and broadband lasing transitions in the LWIR. This leaves nonlinear conversion schemes such as difference-frequency generation as the most common routes yielding ultrashort LWIR pulses of duration comprising only a few electric-field periods.
In this work, Chen and coauthors theoretically discuss an alternative approach for the generation of ultrafast LWIR transients via Raman-based molecular modulation in hydrogen-filled hollow capillaries. The authors propose a double-pulse scheme to overcome fundamental limitations such as the low Raman gain in the LWIR. In this arrangement, coherent molecular oscillations are induced in the gaseous core by the first pulse centered at 0.8 μm. Under the right conditions, a delayed 2 μm-pulse is then inelastically scattered off the pre-existent phonon population to generate few-cycle LWIR pulses at 12 μm. These results might lead to the design of efficient fiber-based LWIR frequency convertors with potential impact across multiple disciplines.
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In this work, Chen and coauthors theoretically discuss an alternative approach for the generation of ultrafast LWIR transients via Raman-based molecular modulation in hydrogen-filled hollow capillaries. The authors propose a double-pulse scheme to overcome fundamental limitations such as the low Raman gain in the LWIR. In this arrangement, coherent molecular oscillations are induced in the gaseous core by the first pulse centered at 0.8 μm. Under the right conditions, a delayed 2 μm-pulse is then inelastically scattered off the pre-existent phonon population to generate few-cycle LWIR pulses at 12 μm. These results might lead to the design of efficient fiber-based LWIR frequency convertors with potential impact across multiple disciplines.
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Article Information
Femtosecond long-wave-infrared generation in hydrogen-filled hollow-core fiber
Yi-Hao Chen, Jeffrey Moses, and Frank Wise
J. Opt. Soc. Am. B 40(4) 796-806 (2023) View: HTML | PDF