Open AccessFranz-Keldysh effect in two-photon absorption
Author(s) -
Cui Hao-Yang,
Zhifeng Li,
Yajun Li,
Zhaolin Liu,
Xiaoshuang Chen,
Wei Lü,
Zhenhua Ye,
Hu Xiao-Ning,
Chong Wang
Publication year - 2008
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.57.238
Subject(s) - absorption (acoustics) , attenuation coefficient , two photon absorption , optics , space charge , physics , photon , photodiode , atomic physics , laser , intensity (physics) , optoelectronics , materials science , electron , quantum mechanics
The Franz-Keldysh effect in the two-photon absorption process in the space charge region of an Hg0.695Cd0.305Te 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-response 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.