I remember I found the following very helpful during my Master's in Photonics: 

Nonlinear Optics of Organic Molecules and Polymers by Hari Singh Nalwa, Seizo Miyata

One very good book is: Nonlinear Fiber Optics by G. P. Agrawal.

Yes. There are the best books for learning.

Nonlinear optics - Boyd

Ultrashort laser pulse Phenomena - Diels & Rudolf

Boyd and Nalwa are good books!

I recommend this book: Handbook of Nonlinear Optics- Richard L. Sutherland. It introduce many basic theories and experimental technique about nonlinear optical. 

In addition to Boyd's Nonlinear Optics and Yariv's Quantum Electronics (which have already been mentioned), I also have Shen's The Principles of Nonlinear Optics and Butcher&Cotter's The Elements of Nonlinear Optics on my office shelf, and I have found them all very useful for one thing or another. My personal favorite is probably Yariv's book (paired with his other wonderful text Optical Waves in Crystals), but I've often found that it's helpful to look at a few authors' approaches to topics to gain a better understanding. Older editions of all of these books can often be found on second-hand book websites (ebay, thriftbooks, abebooks, etc.), which gave me a way to build up my own library on a student's budget. Good luck in your search.

Quantum Electronics —A Yarive, is very nice

• Handbook of Nonlinear Optics  By  R. L. Sutherland
• Nonlinear Optics  By R. W. Boyd
• The Principles of Nonlinear Optics  By Y. R. Shen
• Handbook of Optics By M. Bass

Dear Dr. Ali Benghia

I suggest you book Physics of Nonlinear Optics, Guangsheng He, Song H. Liu-World Scientific

Nonlinear optics - Boyd

Ultrashort laser pulse Phenomena - Diels & Rudolf

or photonics by Maiman

4,5,and 6 chapters

Nonlinear Optical Crystals by [David N. Nikogosyan

Non linear Optics by Robert Boyd is highly useful and good

Photonics by Maiman is also recommended