Abstract

Using a novel cavity architecture, we report significantly enhanced power and reduced threshold in a stable, single-longitudinal-mode (SLM) pulsed Ti:sapphire laser. The resonator incorporates a conventional grazing incidence cavity¹ with an additional optic (zero-order mirror), which forms a coupled cavity in the form of a Michelson complex reflector.^2,3 Provided that the reflectivity of the zero-order mirror is carefully chosen, the additional coupling induces SLM operation in the laser at modest grating angles. Without the additional coupling, the conventional grazing incidence cavity operates at all times multimode. Moreover, a seven-fold increase in output power and a 1.8 times reduction in operational threshold is reported with the zero-order mirror in position. Conventional SLM grazing incidence resonators are usually engineered to have a short optical length to maximize the cavity-mode spacing, so that only one mode falls within the pass-band of the cavity. In the case of our coupled resonator the need for a short cavity is relaxed, because each potential mode needs to satisfy both cavity arms simultaneously. Indeed, stable SLM is secured by the correct selection of the cavity arm lengths.

© 1996 Optical Society of America