Abstract

Spatial self-focusing in lasers enables pattern formation and nonlinear dynamics in laser fields. Spatial self-focusing e.g. is a possible explanation for self pulsing of a laser field and a stripe pattern moving transversally in the field. These observations [1] were made in photorefractive oscillators (PROs) which are equivalent to class A-lasers. In order to demonstrate self-focusing in the active medium of a lasing unidirectional PRO (active medium: BaTiO3), the beam diameter of the TEM00 mode emitted from a PRO was measured in the near field as a function of the resonator detuning. We find that the beam diameter depends on the detuning like a dispersion function. We observe also that resonator losses increase the width of the dispersion function and decrease the maximum value of self­focusing.

© 1998 IEEE