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1The 30th International Conference on Advanced Laser Technologies LM-I-9
ALT'23
Ultrafast conductivity control by femtosecond lasers
D. Boschetto1
1- Laboratoire d'Optique Appliquée, ENSTA Paris, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris,
Palaiseau, France
Main author email address: Davide.Boschetto@ensta.fr
The field of materials science and nanoelectronics has been revolutionized by the ability to control conductivity through femtosecond laser pulse irradiation, presenting promising opportunities for progress in multiple disciplines. The capacity to induce rapid and transient alterations in the electrical properties of materials has unlocked a wide range of possibilities in optoelectronics, photonics, and information processing. The utilization of femtosecond laser pulses enables precise manipulation of material conductivity, providing exceptional control over their electronic characteristics. This technique offers a distinct advantage compared to conventional methods by allowing rapid modulation of conductivity within femtosecond time scale [1-3]. The ultra-fast timescale facilitates dynamic manipulation of electrical properties, opening the possibility to innovative applications in areas such as ultrafast electronics, high-speed data processing, and advanced photonic devices.
During this talk, we will highlight recent advancements in manipulating material conductivity through the use of femtosecond laser pulses, with a specific emphasis on the interesting phenomenon of photoinduced reduction of conductivity by targeting localized states with a specific pump photon energy [3]. We will focus in particular on incommensurate crystals, which are characterized by a lattice mismatch leading to the presence of localized states that affect the overall conductivity of the crystal. We will demonstrate how targeted excitation can selectively promote electrons to occupy these localized states, offering a means to control and reduce the conductivity of the crystal.
The experimental findings are supported by Density Functional Theory calculations, together with a time-dependent simulation using rate equations and a two-temperature model. These investigations reveal that the conductivity reduction occurs as photoexcited electrons become trapped in the localized energy state of vanadium clusters, which are formed due to the incommensurability of the layered crystal structure.
[1] G. Lantz et al., "Ultrafast evolution and transient phases of a prototype out-of-equilibrium Mott- Hubbard material." Nature Communications 8, 13917 (2017).
[2] N. Yoshikawa et al., "Ultrafast switching to an insulating-like metastable state by amplitudon excitation of a charge density wave." Nature Physics 17, 909 (2021).
[3] M. Lejman et al., "Ultrafast photoinduced conductivity reduction by bonding orbital control in an incommensurate crystal." Submitted.
