Poled amorphous polymers for second‐order nonlinear optics

Recent advances in poled amorphous polymers for second‐order nonlinear optics are discussed with emphasis on stabilizing the frozen‐in nonlinearity via chemical crosslinking under electric fields. Specific examples of a linear polymer and a crosslinked polymer, both with nitroaniline‐type chromophores covalently attached as side groups, are presented and compared in their glass transition behavior, linear optical properties, poling dynamics, and stability of frozen‐in nonlinearity. It is demonstrated that by employing chemical crosslinking under electric fields one can prepare highly efficient and stable poled polymers that exhibit no decay in nonlinearity at ambient conditions and no apparent tendency of decay even at 85°C as well as excellent optical properties. The historical development of organic materials for second‐order nonlinear optics and recent advances in device fabrication based on poled polymers are also discussed briefly. Copyright © 1990 John Wiley & Sons, Ltd.