Nonlinear optical and electro-optic properties of hybrid sol–gels doped with organic chromophores

This paper reports a systematic investigation on the nonlinear and electro-optic properties of hybrid sol–gel doped with azo-type chromophores. The host is based on photosensitive sol–gel prepared from 3-(methacryloxy)propyl trimethoxysilane-zirconium (or aluminum) oxide (MAPTMS-Zr(Al)) hybrid system. The chromophores are incorporated into the hybrid sol–gel as both guest and side-chain. Second harmonic generation experiment is conducted to optimize the poling parameters for the active sol–gel films. The stability of the second-order nonlinear optical coefficients is investigated by temporal decay test and heat-cool cycling experiment at elevated temperature. Electro-optic channel waveguides have been fabricated by direct ultra-violet exposure, direct blue laser writing, and reverse-mesa methods. Electro-optic effect of the waveguides is measured at 1550 nm and optical intensity modulation has been demonstrated. All the results show that the hybrid sol–gels are promising media for electro-optic devices for integrated optics in both performance and fabrication flexibility.