| Abstract: | An optical second-harmonic generator (or spontaneous parametric
down-converter) includes a microresonator formed of a nonlinear optical
medium. The microresonator supports at least two modes that can be phase
matched at different frequencies so that light can be converted between
them: A first resonant mode having substantially radial polarization and
a second resonant mode having substantially vertical polarization. The
first and second modes have the same radial order. The thickness of the
nonlinear medium is less than one-half the pump wavelength within the
medium. |