EXPERIMENTAL-EVIDENCE OF SELECTION AND STABILIZATION OF SPATIAL PATTERNS IN A CO2-LASER BY MEANS OF SPATIAL PERTURBATIONS

We report on experimental evidence of selection and stabilization of u nstable patterns by means of spatial perturbations. Thin metallic wire s, with a diameter comparable to the laser wavelength, are inserted in to a laser cavity to realize the selection and stabilization process. We studied the effects of small displacement of a single wire on the f undamental and annular patterns. The observed phenomena can be explain ed considering the diffractive effects of the wire inside the optical cavity. By using more wires instead of a single wire, square and hexag onal patterns are obtained. (C) 1998 Elsevier Science B.V. All rights reserved.