Energetic mid-IR femtosecond pulse generation by self-defocusing soliton-induced dispersive waves in a bulk quadratic nonlinear crystal

Binbin Zhou, Hairun Guo, Morten Bache
2015 Optics Express  
Generating energetic femtosecond mid-IR pulses is crucial for ultrafast spectroscopy, and currently relies on parametric processes that, while efficient, are also complex. Here we experimentally show a simple alternative that uses a single pump wavelength without any pump synchronization and without critical phase-matching requirements. Pumping a bulk quadratic nonlinear crystal (unpoled LiNbO_3 cut for noncritical phase-mismatched interaction) with sub-mJ near-IR 50-fs pulses, tunable and
more » ... band (∼ 1,000 cm^-1) mid-IR pulses around 3.0 μ m are generated with excellent spatio-temporal pulse quality, having up to 10.5 μJ energy (6.3 conversion). The mid-IR pulses are dispersive waves phase-matched to near-IR self-defocusing solitons created by the induced self-defocusing cascaded nonlinearity. This process is filament-free and the input pulse energy can therefore be scaled arbitrarily by using large-aperture crystals. The technique can readily be implemented with other crystals and laser wavelengths, and can therefore potentially replace current ultrafast frequency-conversion processes to the mid-IR.
doi:10.1364/oe.23.006924 pmid:25836912 fatcat:yvlfsxgjhbgqzmuhrrdjet2u4m