Optical rectification
= Optical rectification
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A static or slowly varying <electric polarization> produced by nonlinear response to an oscillating optical <electric field>. The constant term in <nonlinear optical susceptibility> is its simplest model. An <optical pulse> has a varying envelope, so its cycle-averaged quadratic response can vary during the pulse rather than remaining constant forever. This term alone does not imply a radiated zero-<frequency> wave.