低振幅中心对称光折变暗和灰空间孤子的时间特性

Temporal Behavior of the Low-Amplitude Dark and Gray Spatial Solitons in Centrosymmetric Photorefractive Media

为了研究中心对称光折变晶体中低振幅暗和灰空间孤子的时间特性,推导出了含时间参量的空间电荷场和光波的动态演化方程。采用数值方法,得到了中心对称光折变晶体中低振幅空间暗和灰孤子强度包络和强度半峰全宽的时间演化特性。结果表明,初始阶段形成的宽度较宽的孤子,其宽度随时间单调递减到一个最小值直至稳态孤子的形成;在相同的演化时间内,孤子的半峰全宽随着孤子峰值强度和暗辐射比值的增大而变小。暗和灰孤子有类似的时间演化特性。

In order to study the temporal behavior of the low-amplitude dark and gray spatial solitons in biased centrosymmetric photorefractive crystals,the expressions of time-dependent space-charge field and dynamical evolution equation are obtained.The temporal behavior of the intensity profiles and the intensity full width at half maximum（FWHM） of dark and gray solitons are obtained by numerical method.The results indicate that a broad soliton is generated at the beginning,and as time evolves,the intensity width of photovoltaic spatial solitons decreases monotonously to a minimum value toward steady state.Within the same propagation time,the higher the ratio of soliton peak intensity to the dark irradiation intensity is,the shorter the FWHM of photovoltaic solitons is.Dark and gray solitons have the similar temporal properties.