Abstract
Butt coupling efficiencies as high as 78% and averaging over 65% have been observed in coupling light from constricted double heterostructure large optical cavity lasers (CDH-LOC)(1) to both Ti-LiNbO3(2) and Nb-LiTaO3(3) optical waveguides. Power levels in the waveguide of 13 mW (cw) and 27 mW (5 μs 5% duty cycle pulses) have also been observed. These are the highest reported efficiencies and powers coupled by any means from diode lasers to LiNbO3 waveguides. The observations support the theory relating beam waist size to coupling efficiency(4) at very high waveguide powers and coupling efficiencies.