Hey everyone. I'm currently in a new research lab that focuses on optics. One thing I'm currently tasked with is handling the femtosecond laser we have. However, to do this, I need a stronger background in optics than I currently have (which is a few years of undergrad optics, some quantum, pretty much what is expected of physics undergrads). Specifically, I need to be up to speed with nonlinear optics in order to build what I need to. I know that this isn't a topic that is the main staple of optics textbooks, so I thought to ask here to see if anyone had any insight. What would be a good textbook that I could check out to get me through intermediate optics into nonlinear optics?