Quadratic electro‐optic non‐linearity of a conjugated porphyrin polymer measured in the Q‐band one‐photon resonance region

We reprot linear and non‐liner optical experiments on a new edge‐linked porphyrin polymer that is soluble in pyridine/chlorinated solvent mixtures and that produces optical quality thin films by spin coating. This linear absorption properties of the polymer indicate that it posseses an extended intermacrocycle π‐conjugation. This results in a strong red shift of the macrocycle‐derived Q‐band with the polymer peak at 874 nm (1.42 eV) in solution and 838 nm (1.48 eV) in solid films compared with a monomer solution peak at 642 nm (1.93 eV). The polymer possesses a large Stark‐shift‐related DC Kerr electro‐optic non‐linearity with peak responses in the real and imaginary part of X (3) (−ω; 0, 0, ω) of Re X (3) = −7.2 × 10 −8 esu at 849 nm (1.46 eV) and lm X (3) = 6.7 × 10 −8 esu at 855 nm (1.45 eV). This response is 3–10 tiems larger that that reported for quasi‐one‐dimesional conjugated polymers and enhancements can be anticipated. Detailed examination of the electro‐optic response spectra shows several interesting features which indicated that the usual phenomenological models of molecular Stark shifts do not provide a full description of the abserved behaviour. Future studies are planned to look more closely at the nature of the electro‐optic response.