Bright Phase-Stable Waveforms Covering the Entire Infrared Molecular Fingerprint Region

The recent availability of modelocked-laser architectures emitting MHz-repetition-rate trains of near-infrared (NIR) pulses with multi-W average powers and 10-fs-scale durations has opened up new vistas for spectroscopy in the mid-infrared (MIR) spectral range. Parametric downconversion processes driven by these femtosecond lasers in suitable nonlinear media, in particular intrapulse difference-frequency generation (IPDFG), afford combinations of the desirable properties of MIR sources: broad spectral coverage, high brilliance, and spatial and temporal coherence. Yet, unifying these in a robust and compact radiation source has remained a challenge. Here, we address this challenge by means of IPDFG in a multi-crystal in-line geometry, driven by the powerful, 10.6-fs pulses of a 10.6-MHz-repetition-rate, nonlinearly post-compressed Yb: YAG thin-disk oscillator [1], [2].