Controlled strong-field ionization in Lithium Niobate

The CFEL-ATTO group collaborated in experiments aimed at controlling the ionization of LiNbO3 with strong-field lasers, gaining new insights on the role of microscopic material properties in this fundamental process through femtosecond laser-ablation, a technique often employed in high-resolution micromachining of materials.

A few members of the CFEL-ATTO group collaborated in laser ablation experiments on Lithium Niobate (LiNbO3) crystals, to understand how they react to strong-field driving laser pulses. This fruitful international collaboration was led by the group of Prof. Francois Légaré (INRS; Canada), who is co-supervising Vincent Wanie’s PhD, and also involved scientists from the Chinese Academy of Sciences.


LiNbO3.png

The ablation of LiNbO3 with an asymmetric laser field results in craters (bottom image) with different sizes whether the electric field E is parallel or anti-parallel to the permanent polarization Ps of the material. Credit: Vincent Wanie.

In a first experiment [1], Wanie and co-workers used laser-induced ablation to demonstrate, through a variation of the ablated area, how the permanent polarisation of Lithium Niobate can be exploited to control the ionisation of the material. This was achieved by using femtosecond laser pulses having a well-defined waveform of the electric field. The results provide a first proof-of-principle of such behavior in a solid system and are in direct analogy to permanent polarization effects that were observed in the ionization of asymmetric gas molecules.

In a second experiment [2], they demonstrated through angle-resolved measurements how the variation of the ablated area is sensitive to the crystal structure, revealing the main chemical bonds contributing to the ionization of the material.

These results provide new insights on the strong-field ionization response of one of the most used material in photonics, potentially leading to new applications or to a new degree of freedom in high harmonic generation from LiNbO3, and have been published in Physical Review B. The full references to the publications are reported below.

References:

  1. Control of strong-field ionization in ferroelectric lithium niobate: Role of the spontaneous polarization

    Vincent Wanie, Tian-Jiao Shao, Philippe Lassonde, Heide Ibrahim, Jude Deschamps, Jia-Qi Liu, Fabian Ambriz Vargas, François Vidal, Andreas Ruediger, Francesca Calegari, Xue-Bin Bian, and François Légaré

    Phys. Rev. B 101, 184103 - https://doi.org/10.1103/PhysRevB.101.184103

  2. Laser polarization dependence of strong-field ionization in lithium niobate

    Vincent Wanie, Tian-Jiao Shao, Philippe Lassonde, Francesca Calegari, François Vidal, Heide Ibrahim, Xue-Bin Bian, and François Légaré

    Phys. Rev. B 101, 214311 - https://doi.org/10.1103/PhysRevB.101.214311