Processible main chain polymers with

Kurihara, K., Tomaru, S., Mori, Y., Hikita, M., and Kaino, T., Third-order optical nonlinearities of a processible main chain polymer with symmetrically substituted tris-azo dyes, Appl. Phys. 

The increasing use of optical fibre in the telecommunications network will, ultimately, require all-optical signal processing to exploit the full bandwidth available. This has led to a search for materials with fast, large third order optical nonlinearities. Most of the current materials either respond in the nanosecond regime or the nonlinearity is too small (1-3). Organic materials are attractive because of their ultra-fast, broadband responses and low absorption. However the main problem in the materials studied to date, e.g. polydiacetylenes (4) and aromatic main chain polymers (5), has been the small nonlinear coefficients. 

The similar main chain structures with conjugated diacetylene units (34, 35) can be prepared (equations 32 and 33) by polyaddition or polycondensation using components containing the conjugated diyne units . The processable polymers become insoluble on photoirradiation or by thermal annealing via intermolecular cross-linking. 

Processible Main Chain Aromatic Oxadiazole Polymers with Flexible Linkage. 

Among the many types of processible NLO polymers, polyurethane with symmetrical substituted tris-azo dye with fluorinated alkyl units (PSTF for short) was selected as a waveguide material. PSTF is a novel third-order NLO main-chain polyurethane with tris-azo dye incorporated into the main chain with a fluorinated alkyl backbone [40]. This polymer is similar to the SBAC polymer family whereby a symmetrically substituted 7t-conjugated molecule was incorporated in a main-chain polymer. Azo dye is an effective NLO dye investigated by many researchers and the tris-azo dye is very special for NLO applications. Fluorinated alkyl units are expected to be effective for reducing the polymer... 

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