Spontaneous transverse pattern formation in a microchip laser excited by a doughnut pump profile

A transition from a pure Laguerre–Gaussian (LG) mode to a pattern of optical vortex lattices in a large-Fresnel-number microchip laser is experimentally demonstrated by controlling the cavity Q-factor. The cooperative frequency locking of nearly degenerate modes is found to be a primary process for the generation of the optical vortex lattices in a class-B laser. When the cavity Q-factor is high enough, a LG-like mode and a structure of optical vortex lattices are found to coexist. Competition between coexisting transverse patterns of different symmetry gives rise to chaotic fluctuations. Received: 20 March 2002 / Revised version: 20 May 2002 / Published online: 25 October 2002 RID="*" ID="*"Corresponding author. Fax: +886-35/729134, E-mail: yfchen@cc.nctu.edu.tw