US Patent 7161968 Laser apparatus

In a solid state, optically end-pumped laser, the laser gain medium has a tapered diameter to minimize the maximum path length of barrelling amplified stimulated emission (ASE), and a roughened surface region at one end to scatter barrelling ASE out of the gain medium; thereby minimizing the negative effective of barrelling ASE's, and inhibiting the trapping of rays with a large longitudinal component, but disallowing a cyclic, i.e. repeated, pass path with specular reflections.