“Second-Order Nonlinearities in Silica”

Dr. Aydoğan Özcan

Ginzton Lab,

Stanford University,

CA, USA

Silica, being a centrosymmetric material, does not naturally have a second-order optical nonlinearity. This is the fundamental reason for the lack of any second order nonlinear processes in fiber optic cables. Poling techniques have been developed in the last several years to induce a high second-order nonlinear coefficient in silica on the order of ~0.8 pm/V.  Silica-based electro-optic devices such as modulators, switches, tunable filters or short wavelength sources utilizing this nonlinearity would find important applications in telecommunication networks, data storage and fiber optic sensor applications.  A thorough understanding of the magnitude and extent of the nonlinear region is necessary in order to design practical devices. The characterization of poled silica is made difficult because the
induced nonlinearity is spatially nonuniform and thin (less than 40 µm) and the usual techniques to measure the nonlinearity are not applicable.

In this talk, a group of novel techniques to uniquely characterize the induced nonlinearity profile of poled silica films is discussed. These tools help us to understand the physics of the poling induced nonlinearity  and to improve the poling process. As a result, applying these
characterization tools, a record-high peak nonlinear coefficient of 1.6 pm/V in thermally poled germanosilicate thin films is reported. Finally, initial progress for the design, fabrication and testing of novel  electro-optic devices utilizing this poled glass technology is presented.

Jan. 3^rd, 2005, 13:40, FENS L030