Jong Rak PARK^*, Hyun Su KIM and Jin-Tae KIM

Department of Photonic Engineering, Chosun University 375 Seosuk-dong, Dong-gu, Gwangju 501-759, South Korea

(Received August 18, 2003; Accepted September 8, 2003)

Intracavity frequency doubling of a single-mode Nd:YAG laser using a nonplanar ring cavity is demonstrated. The nonplanar ring cavity consists of a Brewster-angled Nd:YAG crystal placed in a magnetic field, a KTP crystal, and two spherical mirrors. In this design the Nd:YAG crystal acts as both a nonreciprocal polarization rotator and a partial polarizer, and the nonplanar portion of the ring cavity, which is formed by a relative twist angle between the Brewster-angled end surfaces of the crystal, serves as a reciprocal polarization rotator. Eigenpolarization theory for the cavity configuration is presented and a suitable value of the relative twist angle for unidirectional operation is estimated. A single-mode output power of 22 mW at 532 nm is obtained with a 1.2-W diode laser at 809 nm and a laser linewidth of less than 100 kHz is inferred from a beat note frequency spectrum between two identical laser systems.

Key words: Nd:YAG laser, single-mode laser, intracavity frequency doubling, nonplanar ring cavity

^*E-mail address: ejrpark@chosun.ac.kr