A new cross-linked second-order nonlinear optical material based on an alkoxysilane dye and a multifunctional phenoxyl molecule has been investigated. The design approach to this polymer system is also discussed. The nonlinear optical chromophore can be directly bound to an aryl-bridged network during the curing process. After cross-linking at 200 °C for 30 min, the cross-linked polymeric material was found to be amorphous with a Tt of 110 °C and a degradation temperature of 278 °C. The poled and cross-linked sample exhibits a second-order nonlinear optical coefficient, d33, of 77 pm/V. After being subjected to thermal treatment at 105 °C for 24 h, a reduction of only 19% of d33 was observed for the poled and cured sample. This d33 value remained unchanged at 105 °C for another 144 h, to which measurements were carried out. Detailed characteristics of the cross-linked material are discussed.Recently, a cross-linked system based on an alkoxysilane dye and phenylsiloxane polymer was reported.9 Upon