Non-linear Optics
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Exploiting the Raman effect in a microsphere, we were able to explore lasing using Erbium doped fiber.  The microspheres were fabricated by melting the tip of a optical fiber, and allowing surface tension induced reflow to occur.  This creates ultra-smooth surfaces which results in ultra high Q devices. 

Additionally, we have demonstrated the first Raman  laser on a microelectronic silicon chip. The device uses  the high field intensity within an ultra-high-Q microcavity  to achieve a lasing based on the exceedingly weak Raman nonlinearity  of silica.

Microtoroids with quality factors in excess of 107 have been fabricated by replacing the thermal oxide with sol-gel.  Their ultra high quality factors allowed for the investigation and demonstration of Raman lasing in sol-gel resonators.

Optical parametric interactions are energy and momentum conserving processes, in which  the material only passively catalyzes the interaction of photons. They are the basis of both applied and fundamental studies, and  allow the generation of entangled and nonclassical states of light.  We have recently observed optical  parametric oscillation in silica microcavities.

Caltech optics microcavity microtoroid microresonator array optical micro-cavity photonics laser microlaser Stimulated Raman laser rare earth rare-earth Kerr effect thermo-optic effect near-IR visible laser microsphere silica microelectronic chip on-a-chip on a chip high Q quality factor ultra high Q parametric oscillation non-linear optical effects nonlinear optical effects