Abstract-Effect of the impurity on the Aharonov-Bohm oscillations and the intraband absorption in GaAs∕Ga1−xAlxAs quantum ring under intense THz laser field

M.G. Barseghyan, V.N.Mughnetsyan, L.M.Pérez, A.A. Kirakosyan, D. Laroze



https://www.sciencedirect.com/science/article/pii/S1386947718315960

The simultaneous effect of intense THz laser field and hydrogenic donor impurity on Aharonov-Bohm effect in a GaAs∕Ga1−xAlxAs single quantum ring is investigated using the non-perturbative Floquet theory in high-frequency limit and Ehlotzky approximation. It is shown that the intense THz laser field and donor impurity destroy the usual Aharonov-Bohm oscillations of the electron ground state. The Aharonov-Bohm-like oscillations of the excited energy levels, as well as the dipole, allowed optical transition energies can be effectively controlled by changing the laser field parameter and impurity position. Furthermore, an unusual oscillatory behavior is also observed for the dependence of optical transition intensity on magnetic field induction. The obtained results indicate the possibility of the prediction and effective control of electronic and optical properties of future devices on quantum rings.

Abstract- Intense Terahertz Radiation Effect on Electronic and Intraband Optical Properties of Semiconductor Quantum Rings

 H. M. Baghramyan, M. G. Barseghyan, A. A. Kirakosyan, D. Laroze,

https://www.springerprofessional.de/intense-terahertz-radiation-effect-on-electronic-and-intraband-o/16090972

The current chapter aims to theoretically demonstrate that intense Terahertz (THz) laser field can be a powerful method for the controlling of electro-optical properties of quantum rings (QRs). We explore the electronic and impurity states, charge localization and intraband optical phenomena in GaAs/GaAlAs$\text{GaAs/Ga}\text{Al}\text{As}$ QRs irradiated by the intense THz laser field. Single and concentric double QRs, as well as artificial molecules formed by the laterally aligned QRs are explored. It is demonstrated how the laser field modifies the energy spectrum and wave functions by the strong distortion of the original cylindrical geometry of quantum confinement. Moreover, our findings give an insight on the laser field-affected inter-ring coupling of concentric double QRs and dissociation of QR molecules. Additionally, the new way of control of quantum-confining Stark effect with intense THz laser field is introduced.

Abstract-A quantum rings based on multiple quantum wells for 1.2–2.8 THz detection

Alireza Mobini, M. Solaiman,

https://www.sciencedirect.com/science/article/pii/S1386947717320027

In this paper optical properties of a new QR based on MQWs have been investigated for detection in the THz range. The QR composed of a periodic effective quantum sites that each one considered as QW in theta direction. Using Tight binding method, eigen value problem for a QR with circumstance of 100 nm number with different number of wells i.e. 2, 4, 6 and 8 are solved and the absorption spectrum have been calculated. The results show that absorption has maximum value in range of (1.2–2.88 THz) that can be used for THz detection. Finally, it is realized that by increasing the number of wells, the numbers of absorption line also increase.

Abstract-Controllable Continuous evolution of electronic states in a single quantum ring

Tapash Chakraborty, Aram Manaselyan, Manuk Barseghyan, David Laroze

(Submitted on 18 Jul 2017)

https://arxiv.org/abs/1707.05727

Intense terahertz laser field is shown to have a profound effect on the electronic and optical properties of quantum rings, where the isotropic and anisotropic quantum rings can now be treated on equal footing. We have demonstrated that in isotropic quantum rings the laser field creates irregular AB oscillations that are usually expected in anisotropic rings. Further, we have shown for the first time that intense laser fields can restore the {\it isotropic} physical properties in anisotropic quantum rings. In principle, all types of anisotropies (structural, effective masses, defects, etc.) can evolve as in isotropic rings, in our present approach. Most importantly, we have found a continuous evolution of the energy spectra and intraband optical characteristics of structurally anisotropic quantum rings to those of isotropic rings, in a controlled manner, with the help of a laser field.