Lecture
This lecture covers the non-perturbative susceptibility in nonlinear optics with a focus on solving equations of motion for the density matrix under monochromatic drive. It discusses coherence, dipole moment, and polarization, emphasizing the optical Bloch equations and density matrix. The lecture also explores power broadening, absorption coefficients, and saturation intensity for different detunings, providing insights into microwave absorption in NV centers in diamond.