双光子光折变晶体中宽光束的调制不稳定性

摘要

To study the modulation instability of one-dimensional broad optical beams in biased two-photon photovoltaic photorefractive crystals under steady-state conditions, we obtain the one-dimensional modulation instability growth rates by globally treating the space-charge field. The characteristics of the one-dimensional modulation instability growth rates have been numerically investigated. The numerical results show that the modulation instability growth rates will increase as the external electric field enhancing for positive electric field whereas the growth rates will decrease as the absolute value of the external electric field enhancing for negative electric field when the incident optical intensity is a constant. When the external electric field is given,the modulation instability growth rates will increase as the incident optical intensity enhancing. When the external field is absent, the modulation instability in two-photon photovoltaic photorefractive crystals can be deduced. When the photovoltaic effect is neglectable,we obtain the modulation instability growth rates in biased non-photovoltaic photorefractive crystals.%为了得到稳态情况下一维宽光束在有偏压双光子光伏光折变晶体中的调制不稳定性的结果,通过空间电荷场的非局域性处理得到得了一维调制不稳定性的增长率.采用数值分析的方法对一维调制不稳定性的增长率的特性进行了理论分析.结果表明:在入射光束强度一定的情况下,外加电场为正值时,调制不稳定性增长率随电场的增加而增大,当外加电场为负值时,调制不稳定性增长率随外加电场的绝对值的增大而减小.在外加电场给定时,调制不稳定性增长率随入射光强的增大而增加.当外加电场为零时,可得到双光子光伏光折变晶体中调制不稳定性增长率的结果.当忽略光伏效应,可得到有偏压非光伏光折变晶体中调制不稳定性增长率的结果.