Two-photon absorption and color centers: Effects on all-optical switching.
AuthorDeLong, Kenneth Wayne.
AdvisorStegeman, George I.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThis dissertation explores the effects of two-photon absorption and color center induced absorption on all-optical switching devices. The amount of allowable two-photon absorption was quantified by the parameter T = 2βλ/n₂, where λ is the operating wavelength, β is the two-photon absorption coefficient, and n₂ is the nonlinear refractive index coefficient, the latter two being measured at λ. If the value of T exceeds unity, the operation of all-optical switching devices is in general degraded beyond usable regimes. This result was demonstrated by numerical experiments on systems of equations modelling a nonlinear directional coupler, a prototypical all-optical switching device. The value of T was measured in two fibers, one made of lead silicate glass, and one made of TiO₂-doped silica. We find the value of T to be greater than unity at a wavelength of 1.06 μm in both fibers. Significant color center formation was seen in the lead glass fiber. These color centers were created through two-photon absorption and destroyed through one-photon absorption. Color center induced absorption was seen to mimic two-photon absorption in certain regimes. The nonlinear optical response of semiconductor-doped glasses, an example of a one-photon resonant nonlinearity, was studied. A relaxation time which is dependent on the carrier density was found to be important when modelling the response of these glasses.
Degree ProgramOptical Sciences