Abstract
It was shown that the Brewster-angle-cut Ti:S crystal acts as a birefringent filter in a bare cavity without additional tuning elements. The birefringence effect was studied to understand the pulse-forming mechanisms of the passively mode-locked Ti:S lasers. The laser is a 6-mirror cavity with a 2-cm-long AR-coated c-cut Ti:S crystal as the gain medium, a dye (HITCI) jet as the saturable absorber, and a 5% output coupler. The Ti:S rod, together with the linear polarizer (or the Brewster-angled compensation prisms) and the Brewster-angled dye stream, form a birefringent filter. The birefringence phenomenon was observed by rotating the Ti:S rod with respect to the optical axis of the laser cavity.