Mid-infrared frequency domain optical parametric amplifier

Abstract

We report on an optical architecture delivering sub-120 femtosecond laser pulses of 20 µJ tunable from 5.5 µm to 13 µm in the mid-infrared range (mid-IR). The system is based on a dual-band frequency domain optical parametric amplifier (FOPA) optically pumped by a Ti:Sapphire laser and amplifying 2 synchronized femtosecond pulses each with a widely tunable wavelength around 1.6 and 1.9 µm respectively. These amplified pulses are then combined in a GaSe crystal to produce the mid-IR few-cycle pulses by means of difference frequency generation (DFG). The architecture provides a passively stabilized carrier-envelope phase (CEP) whose fluctuations has been characterized to 370 mrad RMS.

High-Order Harmonic Generation in Solids: The Role of Intraband Transitions in Extreme Nonlinear Optics

“…Strong-field physics in solids, however, is not so straightforward to study because the strong excitation conditions required for HHG usually damage the material. Thus, nonresonant excitation is required, which means that we need laser light in the terahertz or mid-infrared range, − depending on the chosen solid. Fortunately, the development of intense laser sources in the terahertz and mid-infrared frequency regions has enabled us to apply low-frequency electric fields with intensities comparable to the critical field strength (the strength of the atomic potential; a few volts per nanometer).…”