Abstract

The nonlinear susceptibility of the first soluble polydiacetylenes was measured by Chance¹ in 1980, and poly(3BCMU) and poly(4BCMU) were among these. Most of the work done on χ⁽³⁾ in poly(3BCMU) and poly(4BCMU) since have been measurements taken in solutions of the polymers, or in gels of the polymers in nonsolvents. These materials can be processed into thin films by spin-coating from concentrated solutions. This forms an amorphous film where the chains are aligned randomly in the plane of the film. It is not surprising therefore to see the published values of n₂ for these amorphous films are an order of magnitude lower than for the crystalline poly(PTS), as the polarized electric field is not interacting with the maximum number of delocalised electrons. The work of Hsu² shows that if the poly(BCMU) films are deposited with the chains aligned the nonlinearity increases by a factor of 5 on the spin coated films and approaches the value of n₂ for poly(PTS). The work of Rochford³ and Townsend⁴ have been the only channel waveguide experiments in poly(4-BCMU). No channel waveguide experiments to measure n₂ have been reported in poly(3-BCMU).

© 1996 Optical Society of America