We find that soft-aperture Kerr-lens mode locking (SAKLM) in a Ti:sapphire laser always takes place around certain discrete cavity configurations accompanied by peculiar beam patterns. By correlating the superposition of proper transverse modes to the observed beam patterns and fitting the beat frequencies to the resonance equation, we discovered that the patterns for SAKLM are formed by phase locking of the fundamental mode with specific degenerate transverse modes that occur near different degenerate cavity configurations. As predicted by the stability analysis, period-3 and period-2 SAKLM does occur around the 1/3- and 1/4-degenerate cavity configurations, which cannot be fully explained in terms of total mode locking of TEM 00 and TEM01 modes. ? 2001 Optical Society of America.
Relation:
Journal of the Optical Society of America B: Optical Physics 18 (8) , pp. 1069-1075
