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A cross-linked polyurethane with a novel nonlinear optical (NLO) chromophore [2-(4′-N,N-dihydroxyethylphenylazo)-3,5-dinitrothiophene] covalently incorporated for second-order optical nonlinearity was developed. High optical-quality films can be obtained from the prepared polymer. Resonance-enhanced second-harmonic coefficient (d33) of 66 pm V−1 at 1.064 μm fundamental wavelength of the poled films was obtained. Test on temporal stability shows that when the films were kept in an oven at 100°C for 1000 h in air, 75% of the NLO signal still remained.

2-Aminothiophene derivatives are the key intermediates for the present synthesis. It is known that the synthesis of 2-aminothiophene is troublesome although it is a rather simple heterocycle. In this work, an early report was newly developed as a basis for the efficient synthesis of thiophene-ring-containing chromophore components for photonic polymers. 2-Amino-5-nitrothiophene and 2-amino-3,5-dinitrothiophene were synthesized in excellent yield. After diazotization, the 2-aminothiophene derivatives were directly treated with N-phenyldiethanolamine to afford two-electron push–pull compounds. A similar styryl compound was also prepared. All of these chromophore molecules have further polymerizable hydroxy groups on one end of the molecule. These compounds are currently showing interesting potential in making highly sensitive, nonlinear optical polymeric materials.

2-Aminothiophene derivatives are the key intermediates for the present synthesis. It is known that the synthesis of 2-aminothiophene is troublesome although it is a rather simple heterocycle. In this work, an early report was newly developed as a basis for the efficient synthesis of thiophene-ring-containing chromophore components for photonic polymers. 2-Amino-5-nitrothiophene and 2-amino-3,5-dinitrothiophene were synthesized in excellent yield. After diazotization, the 2-aminothiophene derivatives were directly treated with N-phenyldiethanolamine to afford two-electron push–pull compounds. A similar styryl compound was also prepared. All of these chromophore molecules have further polymerizable hydroxy groups on one end of the molecule. These compounds are currently showing interesting potential in making highly sensitive, nonlinear optical polymeric materials.

Summary Optical loss (OL) is a fundamental and essential parameter of optical materials. It is defined as 10 times the logarithm of light transmittance I/Io, i.e., where Io and I are the intensities of the incident and transmitted light.