We report on continuous-wave blue-green light generation by direct frequency doubling a monolithically integrated master oscillator power amplifier laser diode in a potassium niobate (KNbO3) crystal. A maximum of 15 mW of nearly diffraction limited (M2 ≤ 1.1) second-harmonic light at 491 nm is generated with a fundamental power of 940 mW incident on a 17 mm long crystal. The fully polarised blue-green radiation is single-longitudinal mode. The root-mean-square fluctuation of the second-harmonic output power is as low as 0.1 % and the power drift is smaller than 1 % over 10 hours of operation.
© 1996 Optical Society of AmericaPDF Article