T. Pliska, D. Fluck, P. Günter, L. Beckers, and C. Buchal, "Efficient blue light second-harmonic and sum-freqyency generation in ion-implanted KNbO3 channel waveguides,"
in Conference on Lasers and Electro-Optics, D. Killinger, G. Valley, C. Chang-Hasnain, and W. Knox, eds.,
Vol. 11 of OSA Technical Digest
(Optical Society of America, 1997), paper CFB3.