Single mode operation in a pulsed Ti:sapphire laser oscillator with the grazing incidence four-mirror cavity

We demonstrate stable single mode operation in a pulsed Ti:sapphire laser oscillator with novel grazing incidence four-mirror (GIFM) coupled cavity. This cavity consists of a grating, a gain medium, and four mirrors and, therefore, has four-arm interferometer configuration. Through the interferometric effect, we could suppress the adjacent modes and obtain stable single mode operation with a bandwidth of <200 MHz. We also have developed the general analysis of the laser modes and threshold conditions for this configuration and the experimental results were agreed well with the theoretical predictions.