Single-pass frequency doubling of laser diodes extends the wavelength
range of infrared laser diodes to blue-green wavelengths. We describe
the first experiments of frequency doubling of a coherent, high-power,
monolithic master oscillator power amplifier (M-MOPA) laser diode. Th
e output from a 1-W M-MOPA is frequency doubled in a single pass throu
gh an 8.2-mm-long KNbO3 crystal. We obtained 3.7-mW diffraction-limite
d output power at a wavelength of 491 nm and demonstrated modulation a
t 20 MHz.