Different samples were prepared by doping azo dye 4'-[[2-(acryloyloxy) ethyl]-ethylamino]-4-nitroazobenzene (DR1), 4'-[[2-(acryloyloxy) ethyl]-ethylamino]-2-chloro-4-nitroazobenzene (DR13) and 4'-[2-2-(acryloyloxy) ethyl]-4-nitroazobenzene (DR19) in poly (methyl methacrylate) (PMMA) polymer films. The optical switching effects of the composites were measured by using linearly polarized 514 nm pump beam from an Ar+ laser (514 nm,CW) and a linearly polarized probe beam from a He-Ne laser (632.8 nm, CW). It was found that the sample containing the chromophores with strong pull/push electronic potential showed larger birefringence but slow response, which mainly came from the photoinduced reorientation process of the chromophores. The sample containing the chromophores with weak pull/push electronic potential showed small birefringence but fast response, which was attributed to the faster angular hole burning process of the chromophores.