折射率线性调制晶体中的稳态倍频研究  

Research on Static Frequency Doubling in Refractive-Index Modulated Crystals

作　　者：黄金哲[1] 毛蓓丽[1] 戴菡[1] 沈涛[1] 张留洋[1] 

机构地区：[1]哈尔滨理工大学光信息科学与技术系,黑龙江哈尔滨150080

出　　处：《光学学报》2010年第9期2634-2638,共5页Acta Optica Sinica

基　　金：黑龙江省自然科学基金(F200509)资助课题

摘　　要：从麦克斯韦方程出发,推导了折射率线性调制介质内的平面波倍频耦合波方程,并给出了稳态耦合波方程的小信号解。由菲涅耳函数所描述的小信号解给出了不同于典型sinc函数的失谐函数结构。分析结果表明,折射率线性调制晶体相对于普通非线性晶体具有更大的匹配带宽,从而拥有更大的可接受温度和匹配角以及光谱带宽;然而这种带宽的增加是以牺牲整体的转换效率为代价的。值得关注的是通过选取特定的折射率调制参量可使失谐函数平坦化,这降低了倍频晶体对于由环境温度、机械结构等原因造成的工作点漂移的灵敏度。通过高转换效率下的数值模拟发现,失谐函数特性仍与低转换效率下的基本结论相符,只是在数值上略有不同且依赖于耦合强度。Starting from the Maxwell equations,a set of coupled plane-wave equations of frequency doubling in the refractive-index modulated medium is derived,and a solution to the equations is given under the small-signal approximation. The small-signal solution,a form composed of Fresnel functions presents a special dephasing structure which is different from the typical sinc function. Analysis shows that the refractive-index modulated crystal has a larger phase matching bandwidth than that in a normal nonlinear crystal,so possesses larger temperature,phase matching ange and spectral bandwidths; however the total conversion efficiency has to make sacrifice to pay for this enhancement of bandwidths. It should be noted that the dephasing function can be flattened with a suitable modulating parameter,which will lower the sensitivities of the frequency doubling crystal to erratic shifts of working points out of any thermal and mechanical reasons. It is found by a simulation in the high conversion efficiency case,the characteristics of dephasing function are still in accordance with the result from the small-signal approximation,except rendering a magnitude difference which depends on coupling strength.

关 键 词：非线性光学 倍频 折射率调制 转换效率 

分 类 号：O437[机械工程—光学工程]