A frequency stabilized ring dye laser was developed in this study. To stabilize the laser frequency, single longitudinal mode must be operated and control the cavity length very finely by using PZT control. To operate the ring laser as a single longitudinal mode, unidirectional operation and wavelength tuning elements are necessary. Faraday isolator was fabricated for unidirectional operation in this experiment. Birefringent filter and Fabry-Perot etalon glass plate were also fabricacated and used to tune the laser wavelength. The Faraday isolator is composed of a quartz plate(thickness : 17mm) and a Faraday rotator which was made of FR-5 glass(Hoya, length:25mm) inside 7 serial annular type permanent magnets(~400Gauss). It makes the ring dye laser beam to propagate unidirectionally. The ratio of the powers of the clockwise- and the counter-clockwise- propagating beams of the ring laser was measured to be over 1000. A solid etalon(thickness: 10mm) and three stages birefringent filter (quartz plates of thickness: 0.015",0.030", and 0.225") were installed inside the ring laser cavity to obtain longitudinal single mode operation. A confocal Fabry-Perot cavity (Finesse~100) was used as a frequency reference cavity to generate error signal which was amplified and fed back to the PZT(PZT5H:Vernitron Co.) attatched to the output coupler to control the cavity length. Single mode output power of the ring dye laser was 210mW when pumping power of CW $Ar^+$ laser(spectal-physics model # : 165) was 3W. This ring dye laser system has the frequency fluctuation less than 1MHz within 30 minutes.
