Abstract

Self starting passively mode locked lasers based on active fiber gain media and using different basic nonlinear mechanisms have been demonstrated. Examples include a nonlinear amplifying loop mirror [1,2], polarization rotation schemes [3] and a multiple quantum well saturable absorber [4]. This paper reports on a compound Erbium doped fiber/semiconductor laser structure where a diode laser amplifier is used as an intracavity saturable absorber. The laser makes use of the relatively fast diode recovery time constant (~1ns) in comparison to the long fiber gain time constant (~10ms) to initiate self starting pulse generation. Once the pulses build up, the laser stabilizes as a soliton source. This means that the laser stabilizes on a combination of peak power and a pulse width (of 1ps) such that the 1ps pulse constitutes a first order soliton in a conventional fiber, with a dispersion of 20ps/nm km. An actively mode locked soliton laser which also makes use of a modulated diode laser amplifier and a fiber loop, generating 25ps wide pulses, has recently been demonstrated [5].

© 1993 Optical Society of America