CC BY
5*
ALT'23 The 30th International Conference on Advanced Laser Technologies
N-I-17
Photoresponse of a two-dimensional electron gas to structured terahertz radiation
S.A. Tarasenko
Ioffe Institute, 194021 St. Petersburg tarasenko@coherent.ioffe.ru
Structured radiation, such as intensity and polarization gratings, and twisted beams carrying orbital angular momentum, has a variety of application in physics, chemistry, and biology [1]. The interaction of structured radiation with semiconductor systems is of particular interest from fundamental point of view and is crucial for the development of optoelectronics [2,3].
Here, we explore the photoresponse of a two-dimensional electron system to the terahertz radiation with structured intensity, polarization, and phase [4]. It is shown that, besides the photothermoelectric current associated with the intensity gradient, the photocurrent contains contributions driven by the gradients of the Stokes polarization parameters and the phase of the electromagnetic field. In particular, the photocurrents are induced by the radiation with a uniform intensity but spatially varying polarization, e.g., at the boundary between the domains excited by radiation with different polarizations. The total current emerging at the boundary of the domains excited by circularly polarized radiation with the opposite helicity flow along the boundary and does not depend on the boundary structure nor the electron gas mobility in the high-frequency limit. This current can be interpreted as the chiral edge current between the photo-induced topological phases with the opposite Floquet-Chern numbers. In the framework of the Boltzmann kinetic approach, we develop a microscopic theory of the non-linear non-local intraband transport of electrons induced by electromagnetic field of structured radiation and derive analytical expressions for all the photocurrent contributions.
The developed theory is also applied to study the photocurrents induced by the Bessel beams carrying orbital angular momentum. The emergent photocurrents have both radial and azimuthal (vortex-like) components which are controlled by the beam polarization and angular momentum. The radial photocurrents lead to a redistribution of electric charge in the two-dimensional plane and form the radial photovoltage. The azimuthal photocurrents induce a static magnetic field and the corresponding magnetization. The results suggest that the measurement of the photoresponse provides a useful experimental tool to determine the parameters of structured radiation, such as, e.g., the photon spin and orbital angular momentum.
This work was supported by the Russian Science Foundation (project No. 22-12-00211).
[1] A. Forbes, M. de Oliveira, and M. R. Dennis, Structured light, Nat. Photonics, 15, 253 (2021).
[2] Z. Ji, W. Liu, S. Krylyuk et al., Photocurrent detection of the orbital angular momentum of light, Science, 368, 763 (2020).
[3] S. Sederberg, F. Kong et al., Vectorized optoelectronic control and metrology in a semiconductor, Nat. Photonics 14, 680 (2020).
[4] A. A. Gunyaga, M. V. Durnev, S. A. Tarasenko, Photocurrents induced by structured light, arXiv:2306.08099 (2023).
