Laser Pulse Formation by Balanced Self Phase Modulation, Group Velocity Dispersion, Saturable Absorption, and Saturable Gain

Abstract

We examine, experimentally and theoretically, the nonlinear dynamics of a laser which generates pulses as short as 27 fs directly from the laser (1), Fig. 1 . The laser shapes the intracavity pulses by a balanced combination of self phase modulation, group velocity dispersion, saturable absorption, and saturable gain which appears different from the shaping mechanisms in earlier lasers where the pulse shaping was due principally to saturable absorption and gain (2), or to soliton-like mechanisms in an optical fiber (3). The shaping which we discuss also offers advantages over prior modelocking mechanisms in that it yields enhanced stability, a close approach to transform limit, and pulses which are, to our knowledge, the shortest yet generated from a laser.