Optical rectification occurs when an intense light wave passes through a nonlinear material, interacting with the electrons and generating a DC electric field. The process can be understood through the lens of second-order nonlinearity, where the polarization of the material responds quadratically to the electric field of the light. This interaction is mathematically represented as P(2ω) ∝ χ²E²(ω), where P is the polarization, χ² is the second-order nonlinear susceptibility, and E is the electric field of the incident light.
