Urethane-urea copolymers containing siloxane linkages: Enhanced temporal stability and low optical loss for second-order nonlinear optical applications

This paper presents a class of nonlinear optical (NLO) urethane-urea copoly mers,where dimethylsiloxane linkages of different length are incorporated i nto the polymer main chain. For comparison, a urethane-urea polymer having virtually no siloxane units has also been prepared. Results show that for c opolymers with siloxane linkages poled samples have exceptional orientation al stability, consistent in part with strong hydrogen-bonding effects. By t he introduction of siloxane linkages, low optical loss materials suitable f or device-quality applications have been obtained. The low optical loss can be attributed to the relatively lower number density of C-H bonds in the p olymer matrix. Simultaneous realization of enhanced temporal stability and lower optical loss has been achieved in a single polymer system.