NEW POLYAMIDES WITH LARGE 2ND-ORDER NONLINEAR-OPTICAL PROPERTIES

A series of NLO polyamides based on the new monomer 2',5'-diamino-4-(d imethylamino)-4'nitrostilbene (DDANS) has been synthesized. The polyme rs are amorphous and show glass transition temperatures up to 206-degr ees-C. They can easily be processed by spin-coating into thin films of optical quality. These film have been oriented by a corona discharge poling process. Second-order nonlinear optical coefficients (d33) of u p to approximately 40 pm/V at a fundamental wavelength of 1542 nm have been measured. Preliminary results indicate that the orientation of t he dipoles shows no significant relaxation at ambient conditions in 12 0 days after poling. These polymers represent a new approach to the de sign of polymers with large and stable second-order nonlinear optical properties, where the nonlinear optical units are fixed in the polymer backbone with their dipole moments oriented transverse to the main ch ain.