Efficient generation of orange light by frequency-doubling of a quantum-dot laser radiation in a PPKTP waveguide

Orange light with maximum conversion efficiency exceeding 10% and CW output power of 12.04 mW, 10.45 mW and 6.24 mW has been generated at 606, 608, and 611 nm, respectively, from a frequency-doubled InAs/GaAs quantum-dot external-cavity diode laser by use of a periodically-poled KTP waveguides with different cross-sectional areas. The wider waveguide with the cross-sectional area of 4x4 mu m(2) demonstrated better results in comparison with the narrower waveguides ( 3x5 mu m(2) and 2x6 mu m(2)) which corresponded to lower coupling efficiency. Additional tuning of second harmonic light ( between 606 and 614 nm) with similar conversion efficiency was possible by changing the crystal temperature.