%0 Figure %A Zhao, Di %A Li, Fu-li %A Chu, Shih-I %D 2013 %T (a) Quasienergies and (b) time-averaged transition probabilities as a function of the intensity of the cavity-mode field %U https://iop.figshare.com/articles/figure/_a_Quasienergies_and_b_time_averaged_transition_probabilities_as_a_function_of_the_intensity_of_the_/1012236 %R 10.6084/m9.figshare.1012236.v1 %2 https://iop.figshare.com/ndownloader/files/1480058 %K femtosecond enhancement cavity %K intensity %K cep %K 20 fs FWHM %K repetition frequency 10 THz %K HHG power spectra %K multiphoton resonance processes %K multiphoton resonance dynamics %K laser fields %K Atomic Physics %K Molecular Physics %X

Figure 4. (a) Quasienergies and (b) time-averaged transition probabilities as a function of the intensity of the cavity-mode field. The resonance position is at 1.489 × 1011 W cm−2. (c) The enhancement of HHG power spectra by tuning the intensity of the cavity-mode field. For clarity, HHG peaks of the comb structure are connected by a line. The energy separation is fixed at ωαβ = 0.17 au. The CEP shift is fixed at Δ = 0.4385 × 2π. The parameters of the frequency-comb field are peak intensity 1 × 1014 W cm−2, carrier frequency 563.5 THz and repetition frequency 10 THz of 20 fs FWHM Gaussian pulses. The carrier frequency of the cavity-mode field is 10 THz.

Abstract

We present a theoretical investigation of the multiphoton resonance dynamics driven by intense frequency-comb and cavity-mode fields inside a femtosecond enhancement cavity (fsEC). The many-mode Floquet theorem is employed to provide a nonperturbative and exact treatment of the interaction between a quantum system and laser fields. The quasienergy structure driven by the frequency-comb laser field is modified by coupling the cavity-mode field and the multiphoton resonance processes between modified quasienergy states, resulting in the generation of even-order harmonics. The high-order harmonic generation (HHG) from a two-level system driven by the laser fields can be coherently controlled by tuning the laser parameters. In particular, the tuning intensity of the cavity-mode field allows one to coherently control the HHG power spectra without changing the absolute positions of comb frequencies.

%I IOP Publishing