Attosecond Polarization Beats

Feng Yu, Jianping Song, Zhang Yan-Peng +1 more

Chenli Gan, Yanpeng Zhang, Zhiqiang Nie +4 more

Based on color-locking noisy field correlation, the subtle Markovian field correlation effects in three stochastic models have been investigated in studying the Raman- and Rayleigh-enhanced four-wave mixing (FWM). Homodyne and heterodyne detections of the Raman attosecond sum-frequency polarization beats (ASPB), the Rayleigh ASPB, and the coexisting Raman and Rayleigh ASPB have also been investigated, respectively. Raman- and Rayleigh-enhanced FWM processes strongly compete with each other in ASPB. The heterodyne detected signal of ASPB potentially offers rich dynamic information about the homogeneous broadening material phase of the third-order nonlinear susceptibility.

Jianping Song, Yu Feng, Chenli Gan +9 more

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.

Tony Scully

Yanpeng Zhang, Chenli Gan, Jianping Song +6 more

An analytic closed form for the second-order or fourth-order Markovian stochastic correlation of attosecond sum-frequency polarization beat (ASPB) can be obtained in the extremely Doppler-broadened limit. The homodyne detected ASPB signal is shown to be particularly sensitive to the statistical properties of the Markovian stochastic light fields with arbitrary bandwidth. The physical explanation for this is that the Gaussian-amplitude field undergoes stronger intensity fluctuations than a chaotic field. On the other hand, the intensity (amplitude) fluctuations of the Gaussian-amplitude field or the chaotic field are always much larger than the pure phase fluctuations of the phase-diffusion field. The field correlation has weakly influence on the ASPB signal when the laser has narrow bandwidth. In contrast, when the laser has broadband linewidth, the ASPB signal shows resonant-nonresonant cross correlation, and the sensitivities of ASPB signal to three Markovian stochastic models increase as time delay is increased. A Doppler-free precision in the measurement of the energy-level sum can be achieved with an arbitrary bandwidth. The advantage of ASPB is that the ultrafast modulation period 900as can still be improved, because the energy-level interval between ground state and excited state can be widely separated.