Mid-IR femtosecond pulse generation on the microjoule level up to 5 μm at high repetition rates

We show efficient generation of mid-IR pulses tunable between 1 and 5 mu m from 100 kHz class femtosecond systems. The concept can be applied to various sources, particularly based on Ti:sapphire and the newly evolving Yb(+) lasers. The mid-IR pulses are generated as the idler of a collinear optical parametric amplifier pumped by the laser fundamental. The seed for this amplifier is the idler of a previous amplification stage pumped with the second harmonic and seeded with a visible continuum. This enhances the energy and allows us to influence the bandwidth of the final output. Pulses with microjoule energy and Fourier limits of 50 fs are achieved. (C) 2011 Optical Society of America