= Nonlinear optics
{wiki}
<Nonlinear optics> studies the response of matter to <light> when the induced <electric polarization> is not proportional to the driving <electric field>. An intense <laser> can make these additional terms observable. The striking consequence is that a material can emit <light> at a <frequency> absent from the incident beam: <second-harmonic generation> doubles it. This extends a <laser's> usable <optical spectrum> without requiring a second lasing transition.
<Franken and colleagues frequency-doubling experiment> established an optical harmonic in 1961. <Nicolaas Bloembergen's> theoretical work developed the description of interacting <light> waves in nonlinear matter. His 1981 lecture connects a nonlinear constitutive relation with <Maxwell's equations> and explains compensation of <optical dispersion> by <birefringence>.<Nonlinear Optics and Spectroscopy by Nicolaas Bloembergen>[Nonlinear Optics and Spectroscopy, introduction and p. 19]{ref}
Back to article page
