Hi, I'm an electrical engineering student starting research in nonlinear optics, and I'd like some good books to do with nonlinear optics. I'm looking for book similar in style to Nonlinear Optics by Robert Boyd as I really quite like that book. Other books I've gone through include Optical Waves in Crystals by Yariv & Yeh as well as many other books that talk about waveguides, such as Fundamentals of optical waveguides by Katsunari Okamoto (however, I'm looking for something that explains non-linear optics well from an non-electrical engineering point of view, as I want to know how it works). Recommendations much appreciated. Thank you.