Abstract

We designed and built an optical parametric oscillator (OPO) that rotates the image of the resonated wave by 90° on each pass ef the cavity. Our goal is to verify the predictions¹ of high beam quality from such an OPO even for high pufse energy and large Fresnel number. In an earlier paper² we demonstrated improved beam quality for small beam diameters in an image-rotating OPO that used a Dove prism to rotate the image. Here we present a new design using a nonplanar ring resonator and demonstrate good beam quality for larger beam diameters. Figure 1 shows the design of our nonplanar ring. The plane of incidence for mirror M₂ is the horizontal plane and that for mirror M, is the vertical plane. The halfwave plate in leg L₂ maintains the signal wave polarization in the horizontal or extraordinary plane for each cavity pass. The leg lengths and mirror angles are chosen to provide 90° image rotation. Two walkoff compensating crystals are shown but a single crystal should work just as well and our experiments use a single crystal.

© 2002 Optical Society of America