Frequency conversion: non-linear optics

This lecture covers the concept and theory of frequency conversion in non-linear optics, focusing on coupled wave equations, phase matching conditions, and applications like Second Harmonic Generation (SHG) and Quasi Phase Matching. The instructor explains the principles behind non-linear frequency conversion, the importance of phase matching for efficient conversion, and the use of birefringent crystals to achieve quasi-phase matching. Various topics such as sum frequency generation, electron oscillator models, and the wave equation are discussed in detail, providing a comprehensive understanding of frequency conversion in optics.