Fifth-order attosecond sum-frequency polarization beat (FASPB) is studied in a cascade three level system with the phase-conjugation fourth-order coherence function theory. An improved schematic diagram of geometry, which is different from that inducing fifth-order femtosecond different-frequency polarization beat (FFDPB), is used to obtain FASPB. By analyzing the cases that pump beams have either narrow or broad bandwidth, it is found that the temporal behavior of the sum-frequency polarization beat signal depends on the properties of the lasers and transverse relaxation rate of the atomic energy-level system. Finally, the cascaded four-wave mixing (FWM) processes and the difference between attosecond and femtosecond polarization beats have been discussed, it is found that cascaded or sequential lower processes can often obscure the direct fifth-order polarization beat processes.
© 2005 Chinese Optics Letters
(030.1640) Coherence and statistical optics : Coherence
(030.6600) Coherence and statistical optics : Statistical optics
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(320.7110) Ultrafast optics : Ultrafast nonlinear optics
Jianping Song, Yu Feng, Chenli Gan, Long Li, Yuanyuan Li, Xiaojun Yu, Hao Ge, Ruiqiong Ma, Chuangshe Li, Xiangchen Zhang, Yanpeng Zhang, and Keqing Lu, "Fifth-order attosecond polarization beats using twin color-locked noisy lights in cascade three-level system with Doppler-free approach," Chin. Opt. Lett. 3, 230-233 (2005)