晶体损耗对高斯光束孤波演化特性的影响

The Effect of Loss on Solitary Evolution of a Gauss beam in Photovoltaic-Photorefractive Crystal

研究了晶体损耗对高斯光束在光伏光折变晶体中孤波演化特性的影响。结果表明 ,对于给定的高斯光束和光伏光折变晶体 ,损耗将造成入射高斯光束传播时振幅和横截面的不断变化 ,长距离传播时将最终造成入射波的发散。损耗对强失配和弱失配的入射高斯波所造成的影响不同。弱失配时 ,光波横截面随传播距离增大而不断扩大 ,振幅随传播距离单调下降 ;强失配时 ,横截面先压缩后膨胀 ,光波中心振幅则经历先下降后增大 ,再下降的过程。同时我们还发现 ,在一定条件下 ,晶体损耗能使振幅失配的高斯光束演化成匹配的高斯光束 ,并最终演化成稳定的明孤波。

The effect of loss in the photovoltaic-photorefractive crystal on the solitary evolution of a Gaussian beam is investigated. It indicates that, for a given photovoltaic-photorefractive crystal and a proper Gaussian beam, the loss will give rise to the continuous change in amplitude and cross-section during the transmission of the incident Gaussian beam, and for long-distance transmission it will eventually lead to the divergence of the incident waves. For the strong mismatch case, the cross-section of Gaussian beam first compresses and then expands, while the amplitude at the beam center first decreases, then increases and decreases again. In the case of weak mismatch, the intensity and the cross-section will monotonically decrease. It is found that the loss in the crystal can make a mismatched incident Gaussian beam evolve to a matched one, and then become to a steady-state bright soliton.