Thermosetting nonlinear optical polymer: Polyurethane with disperse red 19 side groups

Abstract

A new thermosetting second‐order nonlinear optical polyurethane polymer with disperse red 19 pendant groups was studied by second‐harmonic generation and electro‐optic modulation methods. The polymer can be crosslinked by thermal curing during electric field poling. The electro‐optic coefficient r₁₃ measured with a Mach–Zehnder interferometer ranged from 5 pm/V at 800 nm to 13 pm/V at 633 nm. The polymer crosslinked during poling showed no significant decay of the nonlinearity at room temperature for thousands of hours. A long‐term thermal stability of the dipole alignment at an elevated temperature, 90 °C, was demonstrated. The thermosetting polymer showed improved alignment stability under ultraviolet exposure.