An optical wavelength converting apparatus comprising first and second light
sources
and a nonlinear optical material. Beams from the two light sources, incident on
the material, generate sum frequency light of these beams. The nonlinear optical
material is provided with a periodic structure that matches phases of the beams
from the two light sources with a phase of the sum frequency light of these beams.
Also, wavelengths of the beams from the two light sources and of the sum frequency
light of these beams, polarization directions of these three beams in the material,
and propagation directions of these three beams in the material are determined
such that an efficiency of conversion into sum frequency light does not change
even with a change in one of the defining parameters, thus providing an advantageous
pumping light source.
