Kilohertz-rate continuum generation by amplification of femtosecond pulses near 15 μm

A NaCl color-center amplifier is used to amplify femtosecond pulses from an additive-pulse mode-locked laser at wavelengths between 1.52 and 1.60 microm. Pulse energies of several microjoules are obtained with pulse widths as short as 100 fs at kilohertz repetition rates. These pulses have been used to generate a continuum in a variety of solid and liquid media for hours without optical damage. The continuum generated in BaF(2) covers the wavelength range of 400 nm < lambda < 3.5 microm.