Abstract

Figure 1 shows the image-rotating optical cavity of our singly resonant, nanosecond optical parametric oscillator [1]. The proper choice of mirror orientations gives a 90° rotation of the circulating signal beam on each round trip of the cavity. This rotation separates the resonant frequencies of beams with differing vortex charge, making it possible to select the charge of the signal beam by controlling its frequency through injection seeding with a cw laser.

© 2003 Optical Society of America