Filament-induced visible-to-mid-IR supercontinuum in a ZnSe crystal: Towards multi-octave supercontinuum absorption spectroscopy

• Using a 5 μm femtosecond laser, mid-infrared filamentation is reported in a crystal.
• The induced supercontinuum extends over ∼11 μm and covers the atmospheric transparency window entirely.
• The output profile of the beam, measured in different spectral ranges, shows that multi-filamentation takes place in the bulk.
• As a proof-of-principle experiment, the filament-induced supercontinuum is used for absorption spectroscopy of methane over a ∼10 μm spectral range.

We report on the generation of multiple-octave supercontinuum laser source spanning from 0.5 μm to 11 μm induced by multi-filamentation in a ZnSe crystal. The generated supercontinuum is both spatially and spectrally characterized. It is then exploited in a proof-of-principle experiment for methane spectroscopy measurements by means of the supercontinuum absorption spectroscopy technique. The entire absorption spectrum is successfully recorded within the whole spectral bandwidth of the supercontinuum. Experimental results are in fairly good agreement with the HITRAN database, confirming the reliability and stability over several hours of the generated supercontinuum.