Light intensity modulation element, intensity-modulated-light generating device, laser exposure unit and photograph processing apparatus

摘要

Disclosed is a light-intensity modulation element, which comprises a substrate made of a nonlinear optical crystal, and a light waveguide formed in a principal surface of the substrate to extend in one direction. The light waveguide includes first and second wavelength conversion portions for converting a part of infrared light introduced into the light waveguide to a second harmonic. Each of the first and second wavelength conversion portions has a plurality of polarization structures serially disposed in the longitudinal direction of the light waveguide in such a manner that their polarities in the thickness direction of the substrate are inverted periodically and alternately in the longitudinal direction of the light waveguide. The light waveguide further includes a phase adjustment portion located between the first and second wavelength conversion portions, and associated with a pair of electrodes disposed in opposed relation to one another on opposite sides thereof. The light-intensity modulation element of the present invention can modulate a light intensity in a compact structure and with enhanced efficiency of conversion to second harmonics.