HIGHLY EFFICIENT CW FREQUENCY-DOUBLING OF 854 NM GAALAS DIODE-LASERS IN AN EXTERNAL RING CAVITY

We report on 50% conversion efficiency for frequency doubling of a 854 nm GaAlAs diode laser using a potassium niobate crystal in an externa l ring cavity. Frequency stabilization of the diode laser is achieved by direct optical feedback from the doubling cavity or from a grating in Littrow configuration. We determine 200 kHz linewidth from the meas ured spectral density of the frequency noise and from a beat signal me asurement of two independent diode lasers. The blue output power of 7. 8 mW shows rms-fluctuations of less than 0.6% in 1 MHz bandwidth. (C) 1998 Elsevier Science B.V.