Self-starting mode locked Nd:glass fiber laser using low-temperature-grown GaAs

Summary form only given. The development of semiconductor saturable absorber devices like SESAMs had an important influence on the development of mode locked lasers. The application of semiconductors require special nonlinear optical material with short recombination times in the order of the generated pulses. The complexity of these multi-quantum wells makes them very costly and requires considerable expenses and skill in the production. In the case of Nd:glass with a narrow fluorescence spectrum of about 6 nm the exact placement of the SESAM absorption resonance is difficult to achieve. To avoid these problems we use a novel mode locking device based on a two photon absorption process in bulk low-temperature-grown GaAs (LT-GaAs) whose recombination time is reduced by the creation of a high density of midgap states. We believe that contrary to the reflectivity changing mechanism of SESAMs the limiting process in LT-GaAs is the defocussing of the beam by the generated carriers. In this work we describe the design and the operation of our novel mode locking device based on LT-GaAs combined with a double-clad silica fiber laser doped with Nd/sub 2/O/sub 3/ (1300ppm) emitting at 1053 nm.