2ND-HARMONIC GENERATION FROM THICK ALL-POLYMERIC LANGMUIR-BLODGETT-FILMS PREPARED USING POLYURETHANES

A polyurethane containing 4-dialkylamino-4'-nitroazobenzene (Disperse Red) chromophores has been used as the 'active' layers in alternating Y-type Langmuir-Blodgett films for second-harmonic generation from lig ht of wavelength 1.06 mu m. The choice of 'passive' polymer greatly af fects the intensity of the second-harmonic light, I-2 omega, obtained. With the best 'passive' polymer investigated, the square root of I-2 omega increases in proportion to the number of bilayers in the film up to a thickness of ca. 75 bilayers. The value of I-2 omega decreases s ignificantly over a period of months when the films are stored at 20 d egrees C.