Nonlinear optical devices, problems with

The poled polymer approach is state-of-the-art in terms of the application of polymers to electro-optic devices such as modulators and waveguides. Chromophore-bound polymers for second-order nonlinear optical applications with glass transition temperatures greater than 320°C have been reported (5). However, the electro-optic coefficients are modest, typically less than 10 pm/V at 1.3 im. Part of the poling problem is caused by electrical conductivity at high poling temperatures, which reduces the poling field, or worse, sometimes causes dielectric breakdown. 

It was shown that the thermal stability of conventionally formed polyimide polymers and copolymers (bearing nonlinear optical chromophores) is adequate for numerous device applications. There is a problems, however, with doped systems in that they tend to undergo phase separation. This limits the amount of the nonlinear optics chromophore that can be incorporated into the system. To try and make doping unnecessary, multifunctional polymers were synthesized that contain all the necessary components. One limitation of this technology, however, is the small nonlinear optical response (r33) values for many such poiyimides. This is not true of all of them. 

PP chromophores into electro-optically active materials suitable for fabrication of prototype devices. Our initial focus is a review of problems associated with intermolecular chromophore electrostatic interactions and how these can be niimmuzed by simple structural modification of chromophores. We summarize our experiences with defining maximum achievable optic nonlinearity, minimum optical loss (including processing associated loss), and maximum material stability. This... 

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