Mingxing Jin

Single rotational state preparation via coherent control of laser pulse

We present a scheme to prepare a single rotational state with high probability from an arbitrary superposition state. The NO molecule is used as a computational example. By using a series of linearly and circularly polarized laser pulses and adjusting their parameters, a ground rotational state with probability of 99.982% can be obtained. Starting from the ground rotational state prepared, we can prepare any desired single rotational state with high probability and some rotational superposition states. On this basis, the molecular orientation with initial thermal distribution can be considerably enhanced and well controlled.

Exploration of carrier-envelope phase dependence on the double ionization process of Ar and N2 in few-cycle laser fields

The double ionization dynamics of the Ar atom and the N2 molecule are investigated in few-cycle laser fields with different carrier-envelope phases (CEPs). The corresponding electron momentum distribution of Ar and N2 presents different patterns. The energy distribution of double ionized electron trajectories is also presented to further describe the collision ionization and recollision excitation sequential ionization process of double ionization. Moreover, the angular distribution of the Ar atom and the N2 molecule at the end of a pulse is also sensitive to the CEP. The numerical results indicate that the double ionization mechanisms of atoms and molecules can probably be controlled by adjusting carrier-envelope phase in few cycle fields.

Influence of Higher-Order Kerr Effect on Femtosecond Laser Filamentation in Air at Different Pressures

Utilizing the pressure dependent high-order kerr indices, the propagation of intense ultrashort laser pulse in atmosphere at different pressures can be investigated. The results of spectroscopic investigation provide an effective way to generate supercontinuum as well as higher conversion efficiency high-order harmonic generation.

Molecular ionization of cyclohexanone in femtosecond laser fields: An application of ADK theory

The mechanisms of ionization and dissociation of cyclohexanone (C6H10O) in a 90 fs, 788 nm linearly polarized laser field ranging from 1013 to 1014 W/cm2 by a time-of-flight mass spectrometer (TOF-MS) have been investigated. The ion yields as a function of laser intensity have been measured experimentally. By comparison with the Ammosov-Delone-Krainov (ADK) theory based on a hydrogen-like model, the ionization mechanism of cyclohexanone in this intense femtosecond laser field has been understood. Considering the importance of molecular nuclear motions, we propose that the Franck-Condon (F-C) factor can provide the excess vibrational energy in the molecular ion. This energy is required for the decomposition of the molecular ion which finally results in the observed mass spectrum.

Isolated attosecond pulse generation via the interference of ionized multi-recollision wave-packets

We propose and theoretically demonstrate a method for generating an intense isolated attosecond pulse by a few-cycle strong laser pulse. The numerical simulations show that a broadband supercontinuum spectrum can be obtained by the interference of the ionized multi-recollision wave-packets with different energies, which are produced from the laser field at different ionization instants. By controlling the peak intensity of the few-cycle laser pulse, the atom can be completely ionized in the rising edge of the few-cycle laser pulse. Therefore, the probability of ionized wave packet is large enough to ensure the continuous harmonics with high efficiency, and an intense isolated 77 as pulse can be achieved successfully. Moreover, it is shown that our scheme can modulate the duration of the isolated attosecond pulse by adjusting the initial population of the atom.

State-selection via the quantum coherent control of laser pulse

We propose to prepare arbitrary rotational state from the molecule at low rotational temperature through the quantum coherent of laser pulse, thus providing a scheme to control molecules. On that basis, the molecular orientation at certain temperatures can be remarkably enhanced and well controlled.