Universality in odd-even harmonic generation and application in terahertz waveform sampling

We are happy to announce that Dr. Le Thi Cam Tu and colleagues recently published their work entitled "Universality in odd-even harmonic generation and application in terahertz waveform sampling" in the Physical Review A.

Abstract:

Odd-even harmonic generation contains the system's dynamical symmetry breaking, and its decoding is desirable not only in understanding physics but also for applications of dynamics extraction. In this work we discover a simple universal relation between the odd-even harmonics and the asymmetry of the terahertz (THz)-assisted laser-atomic system: atoms in a primary midinfrared laser pulse combined with a THz laser. We demonstrate numerically and then derive analytically the dependence of the harmonic even-to-odd ratio on the THz electric field. Notably, the functional form of this dependency reveals a universal scaling independent of the parameters of both the primary pulse and atomic target. This universality inspires us to propose a pump-probe scheme for THz waveform sampling from the even-to-odd ratio, accessible from conventional compact setups.