双光子吸收的Franz-Keldysh效应  

Franz-Keldysh effect in two-photon absorption

作　　者：崔昊杨[1] 李志锋[1] 李亚军[1] 刘昭麟[1] 陈效双[1] 陆卫[1] 叶振华[2] 胡晓宁[2] 王茺[3] 

机构地区：[1]中国科学院上海技术物理研究所红外物理国家重点实验室,上海200083 [2]中国科学院上海技术物理研究所功能材料器件中心,上海200083 [3]云南大学工程技术研究院,昆明650091

出　　处：《物理学报》2008年第1期238-242,共5页Acta Physica Sinica

基　　金：国家自然科学基金重点项目(批准号:10234040);国家重点基础研究发展规划项目(批准号:2004CB619004)资助的课题~~

摘　　要：从实验上证实Hg0.695Cd0.305Te光电二极管空间电荷区中存在双光子吸收的Franz-Keldysh效应.利用一个皮秒Nd:YAG激光器抽运的光学参量产生器和差频产生器作为激发光源,测量了入射波长为λ0=7.92μm的脉冲激光所激发的光响应随入射光强的变化关系.脉冲光响应峰值强度随入射光强的增大呈现二次幂函数增强趋势.采用等效RC电路模型将脉冲光伏信号峰值与入射光强相关联,得到空间电荷区中强电场下单光束简并双光子吸收系数.通过对比空间电荷区内外双光子吸收系数得到强场下双光子吸收系数为零场下的2.7倍,出现双光子吸收系数的场致增强效应.这表明不仅带间单光子吸收存在Franz-Keldysh效应,双光子吸收过程同样受到Franz-Keldysh效应的影响.The Franz-Keldysh effect in the two-photon absorption process in the space charge region of an Hg0.695 Cd0.305 Te photodiode is demonstrated. By employing as the exciting light source a pulsed laser beam at λ0=7.92μm from an optical parametric generator and difference frequency generator pumped by a pico-second Nd： YAG laser, the photo-response has been measured as a function of the excitation intensity. The peak intensity of the pulsed photo-respense shows a quadratic dependence on the incident intensity. A relationship between the pulsed photo-voltage and the incident optical intensity has been established with an equivalent RC circuit model to derive the degenerate single beam two-photon absorption coefficient. The results show that the two-photon absorption coefficient within the space charge region of the photodiode is about a factor of 2.7 higher than that outside the space charge region, implying an electric field induced enhancement of the two-photon absorption. This indicates that the Franz-Keldysh effect exists not only in the one-photon absorption process but also in the two-photon absorption process.

关 键 词：Franz Keldysh效应 碲镉汞 双光子吸收 脉冲光伏信号 

分 类 号：O472.3[理学—半导体物理]