Abstract-Electrical generation of terahertz blackbody radiation from graphene

H. M. Dong, W. Xu, and F. M. Peeters

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-26-19-24621

Recent experimental work on the application of graphene for novel illumination motivated us to present a theoretical study of the blackbody radiation emission from a freely suspended graphene driven by a dc electric field. Strong terahertz (THz) emission, with intensity up to mW/cm2, can be generated with increasing electric field strength due to the heating of electrons in graphene. We show that the intensity of the THz emission generated electrically from graphene depends rather sensitively on the lattice temperature in relatively weak electric fields, whereas it is less sensitive to the lattice temperature in relative strong electric fields. Our study highlights the practical application of graphene as intense THz source where the radiation is generated electrically.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Magnetopolaron effect on shallow-impurity states in the presence of magnetic and intense terahertz laser fields in the Faraday configuration

Weiyang Wang, B. Van Duppen, M. Van der Donck, and F. M. Peeters

https://journals.aps.org/prb/accepted/6d07dO43Z4211c3b81984d103a35761924e4abf57

The magnetopolaron effect on shallow-impurity states in semiconductors is investigated when subjected simultaneously to a magnetic field and an intense terahertz laser field within the Faraday configuration. We use a time-dependent non-perturbative theory to describe electron interactions. The externally applied fields are exactly included via a laser-dressed interaction potential. Through a variational approach we evaluate the binding energy of the shallow-impurity states. We find that the interaction strength of the laser-dressed Coulomb potential can not only be enhanced but also weakened by varying the two external fields. In this way the binding energy can be tuned by the external fields and red- or blue-shifted with respect to the static binding energy. In the nonresonant polaron region, a novel magnetopolaron correction that includes the effects of photon process is observed. In the resonant polaron region, moreover, the resonant {\color{black}magnetopolaron} effect accompanied by the emission and absorption of a single photon is distinctly observed. This can be modulated to be far away from the reststrahlen band. The intriguing findings of this manuscript can be observed experimentally and, in turn, provide a new way to measure the strength of the electron-phonon interaction.

Abstract-Infrared to terahertz optical conductivity of n-type and p-type monolayer MoS2 in the presence of Rashba spin-orbit coupling

Y. M. Xiao, W. Xu, B. Van Duppen, and F. M. Peeters

https://journals.aps.org/prb/abstract/10.1103/PhysRevB.94.155432

We investigate the effect of Rashba spin-orbit coupling (SOC) on the optoelectronic properties of n- and p-type monolayer MoS2. The optical conductivity is calculated within the Kubo formalism. We find that the spin-flip transitions enabled by the Rashba SOC result in a wide absorption window in the optical spectrum. Furthermore, we evaluate the effects of the polarization direction of the radiation, temperature, carrier density, and the strength of the Rashba spin-orbit parameter on the optical conductivity. We find that the position, width, and shape of the absorption peak or absorption window can be tuned by varying these parameters. This study shows that monolayer MoS2 can be a promising tunable optical and optoelectronic material that is active in the infrared to terahertz spectral range.

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Abstract-Infrared to terahertz optical conductivity of n-type and p-type monolayer MoS2 in the presence of Rashba spin-orbit coupling

Y. M. Xiao, W. Xu, B. Van Duppen, and F. M. Peeters

https://journals.aps.org/prb/accepted/3e071OaeHf11f739613c9c781af192427469d99cc

We investigate the effect of Rashba spin-orbit coupling (SOC) on the optoelectronic properties of n- and p-type monolayer MoS2. The optical conductivity is calculated within the Kubo formalism. We find that the spin-flip transitions enabled by the Rashba SOC result in a wide absorption window in the optical spectrum. Furthermore, we evaluate the effects of the polarization direction of the radiation, temperature, carrier density and the strength of the Rashba spin-orbit parameter on the optical conductivity. We find that the position, width, and shape of the absorption peak or absorption window can be tuned by varying these parameters. This study shows that monolayer MoS2 can be a promising tunable optical and optoelectronic material that is active in the infrared to terahertz spectral range.

Abstract-Magneto-optical transport properties of monolayer phosphorene

M. Tahir, P. Vasilopoulos, and F. M. Peeters

http://journals.aps.org/prb/abstract/10.1103/PhysRevB.92.045420

The electronic properties of monolayer phosphorene are exotic due to its puckered structure and large intrinsic direct band gap. We derive and discuss its band structure in the presence of a perpendicular magnetic field. Further, we evaluate the magneto-optical Hall and longitudinal optical conductivities as functions of temperature, magnetic field, and Fermi energy, and show that they are strongly influenced by the magnetic field. The imaginary part of the former and the real part of the latter exhibit regular interband oscillations as functions of the frequency ω in the range ℏω∼1.5–2eV. Strong intraband responses in the latter and weak ones in the former occur at much lower frequencies. The magneto-optical response can be tuned in the microwave-to-terahertz and visible frequency ranges in contrast with a conventional two-dimensional electron gas or graphene in which the response is limited to the terahertz regime. This ability to isolate carriers in an anisotropic structure may make phosphorene a promising candidate for new optical devices.

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Abstract-Terahertz plasmon-polariton modes in graphene driven by electric field inside a Fabry-Pérot cavity

C. X. Zhao¹, W. Xu^1,2,a), L. L. Li¹, C. Zhang¹ and F. M. Peeters³

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a) Electronic mail: wenxu_issp@aliyun.com
J. Appl. Phys. 117, 223104 (2015); http://dx.doi.org/10.1063/1.4922401

We present a theoretical study on plasmon-polariton modes in graphene placed inside anoptical cavity and driven by a source-to-drain electric field. The electron velocity and electron temperature are determined by solving self-consistently the momentum- and energy-balance equations in which electron interactions with impurities, acoustic-, and optic-phonons are included. Based on many-body self-consistent field theory, we develop a tractable approach to study plasmon-polariton in an electron gas system. We find that when graphene is placed inside a Fabry-Pérot cavity, two branches of the plasmon-polariton modes can be observed and these modes are very much optic- or plasmon-like. The frequencies of these modes depend markedly on driving electric field especially at higher resonant frequency regime. Moreover, the plasmon-polariton frequency in graphene is in terahertz (THz) bandwidth and can be tuned by changing the cavity length, gate voltage, and driving electric field. This work is pertinent to the application of graphene-based structures as tunable THz plasmonic devices.