2-PI-PULSE LASER USING AN INTRACAVITY QUANTUM-WELL ABSORBER

A broadband solid-state laser is shown to produce stable 2 pi-pulses i n the sub 10 fs time domain by self-induced transparency in an intraca vity single quantum-well absorber. Because of the excitation dependent dephasing of highly excited semiconductors, it is found that besides the laser bandwidth, the achievable pulse duration is self-limited by increasing dephasing at the pulse peak. The pulse duration in a cohere nt GaAs absorber mode-locked Ti:sapphire laser can be decreased down t o a minimum dephasing of 5 fs at the excitation density maximum. In ad dition to the nonresonant Kerr-effect in the laser crystal, the dynami cal bandgap renormalization induces resonant self-phase modulation whi ch is compensated by adjusting a near-zero negative net group velocity dispersion of the resonator. (C) 1998 Elsevier Science B.V. All right s reserved.