Femtosecond mid-infrared laser pulses that are continuously tunable in the wavelength range from 9 to 18μm are demonstrated. These nearly bandwidth-limited pulses are generated by phase-matched difference-frequency mixing within the broad spectrum of 20-fs pulses from a mode-locked Ti:sapphire laser in GaSe. A direct determination of the pulse duration at 11.5μm gives a value of 140 fs. The average mid-infrared power of 1μW is ∼100 times greater than that for infrared generation by non-phase-matched optical rectification.
© 1998 Optical Society of America
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(190.2620) Nonlinear optics : Harmonic generation and mixing
(190.7110) Nonlinear optics : Ultrafast nonlinear optics
(320.2250) Ultrafast optics : Femtosecond phenomena
R. A. Kaindl, D. C. Smith, M. Joschko, M. P. Hasselbeck, M. Woerner, and T. Elsaesser, "Femtosecond infrared pulses tunable from 9 to 18 μm at an 88-MHz repetition rate," Opt. Lett. 23, 861-863 (1998)