Quadrupole second-harmonic generation for a focused beam of arbitrary transverse structure and polarization.
The theory of second-harmonic generation (SHG) that is due to quadrupole and magnetic-dipole second-order optical susceptibilities is developed for monochromatic, focused beams of arbitrary transverse mode structure and polarization character. The strength of SHG depends sensitively on the polarization character of the beam.
Bethune
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