Generation of a broad amplified spectrum in a femtosecond terawatt Ti : sapphire laser by a long-wavelength injection method

A long-wavelength injection method is proposed that will yield a broad ampl ified spectrum in a femtosecond terawatt Ti:sapphire laser. By injecting a seed pulse on the red side of the gain peak and amplifying it to a saturate d fluence level, we could significantly compensate for the spectral narrowi ng that is due to the gain-narrowing effect by use of the amplifying charac teristics of a positively chirped pulse in a gain-saturated regime, and 20- fs, 3-TW pulses could be demonstrated from a Ti:sapphire laser with two mul tipass amplifiers. (C) 1999 Optical Society of America [S0740-3224(99)01407 -1].