Bi-directional operation of Kerr-lens mode-locked Ti:sapphire ring lasers

Summary form only given. A ring laser has certain properties that make it desirable for some applications. In particular, bi-directional mode-locked ring lasers can be used for intracavity measurement of nonreciprocal optical effects. Bi-directional operation was reported in a mode-locked ring Ti:sapphire laser in which an additional pair of curved mirrors introduced a second fold in the cavity. Recently, a similar observation was reported on the increased stability of a linear KLML laser due to addition of an extra fold in the cavity. We compare the conditions of the bi-directional operation of the ring laser with two different cavity configurations: a standard x-cavity with two curved mirrors, and one with an additional x-fold with four curved mirrors. We then compare these lasers with a numerical model of their cavities, and show that the two-fold cavity is more stable. We constructed two mode-locked Ti:sapphire ring lasers, and obtained bi-directional operation in both.