Stable optical resonator made of a pair of flat mirrors and a positive lens: numerical analysis (original) (raw)

This paper presents the numerical analysis of an optical resonator which has in one side a flat coupling mirror and, in the other side, a convergent lens and a flat reflector emulating a concave total reflector mirror. Between the lens and the total reflector flat mirror there is a chopper to promote q-switching operation. This resonator was conceived to be installed in a CW CO2 laser. Two analysis were performed: stability and mode formation. The stability was done by using ray tracing (ABCD matrix) and evaluating the configurations the stability criteria is observed. The mode formation analysis was done by using the Fox and Li formalism. It was concluded that it is possible to find a range of parameters (mirrors and lens distances and focal lengths) that allows stable operation and a convergence to the fundamental mode in just few round-trips inside the resonator. These characteristics are quite desirable for pulsed operation in the TEM00 mode.