The positive and negative travelling wave solitons are predicted in photorefractive crystal biased by positive electric field in the low intensity regime.

• 利用行波变换法,推导出有正偏压光折变晶体中小振幅光波的行波正、负孤子解,证明在有正偏压光折变晶体中存在着正、负行波孤子;