24 research outputs found
Combined complex Doppler and Cherenkov effect in left-handed metamaterials
We derive the formula of the complex Doppler shift in a two-dimensional,
dispersive metamaterial and we show that a moving, monochromatic radiation
source generates multiple frequency modes. The role of the group velocity is
stressed and the Doppler shifted radiation field exhibits features of the
Cherenkov effect. The presented theory is also applicable to the case of a
moving, nonoscillating charge and explains many peculiar characteristics of the
Cherenkov radiation in lefthanded metamaterials such as the backward direction
of power emission, the constant radiation angle and the lack of velocity
threshold.Comment: 11 pages, 7 figure
Ultraslow long-living plasmons with electromagnetically induced transparency
We analytically examine propagation of surface plasmon polaritons (SPPs) at a
thin metallic film between glass substrate and
electromagnetically-induced-transparency (EIT) medium. High-precision and
high-resolution in frequency domain provided by EIT paves the way towards
plasmonic group velocities reduction even by orders of magnitude and
corresponding lifetime enhancement of SPPs up to microseconds.Comment: 5 pages, 5 figure
Excitonic Spectra of Wide Parabolic Quantum Wells
The optical properties of wide Quantum Wells are considered, taking into
account the screened electron-hole interaction potential and parabolic
confinement potentials, different for the electrons and for the holes. The role
of the interaction potential which mixes the energy states according to
different quantum numbers is stressed. The results obtained by our method are
in agreement with the observed spectra and give the possibility to the
assessment of the resonances.Comment: 13 pages, 7 figures typos correcte
Electrooptical Properties of Rydberg Excitons
We show how to compute the electrooptical functions (absorption, reflection,
and transmission) when Rydberg Excitons appear, including the effect of the
coherence between the electron-hole pair and the electromagnetic field. With
the use of Real Density Matrix Approach numerical calculations applied for
Cu0 crystal are performed. We also examine in detail and explain the
dependence of the resonance displacement on the state number and applied
electric field strength. We report a good agreement with recently published
experimental data.Comment: 14 pages, 10 figures, updated and cleared u
Optical Properties of Rydberg Excitons and Polaritons
We show how to compute the optical functions when Rydberg Excitons appear,
including the effect of the coherence between the electron-hole pair and the
electromagnetic field. We use the Real Density Matrix Approach (RDMA), which,
combined with Green's function method, enables one to derive analytical
expressions for the optical functions. Choosing the susceptibility, we
performed numerical calculations appropriate to a Cu0 crystal. The effect
of the coherence is displayed in the line shape. We also examine in details and
explain the dependence of the oscillator strength and the resonance placement
on the state number. We report a good agreement with recently published
experimental data.Comment: 16 pages, 5 figures, submitted to PR
Electro-optical properties of CuO in the regime of Franz-Keldysh oscillations
We present the analytical method enables one to compute the optical functions
i.e., reflectivity, transmission and absorption including the excitonic effects
for a semiconductor crystal exposed to a uniform electric field for energy
region above the gap, for external field suitable to appearance of
Franz-Keldysh (FK) oscillations. Our approach intrinsically takes into account
the coherence between the carriers and the electromagnetic field. We
quantitatively describe the amplitudes and periodicity of FK modulations and
the influence of Rydberg excitons on FK effect is also taking into account. Our
analytical findings are illustrated numerically for excitons in CuO
crystal.Comment: 12 pages, 10 figure
Complex Doppler effect in left-handed metamaterials
The Doppler shift is investigated in one-dimensional system with moving
source. Theoretical findings are confirmed in numerical simulations of optical
and acoustical waves propagation in simple metamaterial model, showing the
reversed shift and the existence of multiple frequency modes. The properties of
these waves are discussed. The effect of absorption on the phenomenon is
outlined.Comment: 9 pages, 10 figures, added reference and corrected typo
Nonlinear Optical Properties and Self-Kerr Effect of Rydberg Excitons in CuO
We show how to compute the nonlinear optical functions (absorption,
reflection, and transmission) for a medium with Rydberg excitons, including the
effect of the coherence between the electron-hole pair and the electromagnetic
field. Using the Real Density Matrix Approach the analytical expressions for
nonlinear optical functions are obtained and numerical calculations for Cu0
crystal are performed. We report a good agreement with recently published
experimental data. Propagation of the electromagnetic waves in Rydberg excitons
media with nonliner effect is also discussed and the possibility of obtainig
self-phase modulation due to Kerr nonlinearity is investigated.Comment: 8 pages, 6 figure
Excitons in Cu2O -- from Quantum Wells to Bulk Crystals and Additional Boundary Conditions for Rydberg Exciton-Polaritons
We propose a scheme for calculation of optical functions of a semiconductor
with Rydberg excitons, for a wide interval of dimensions. We start with
2-dimensional structure, then going to thin films and ending on 3-dimensional
bulk crystals. The calculations including the polaritons are performed, the
case of large number of polariton branches is discussed and obtained
theoretical absorption spectra show good agreement with experimental data.Comment: 9 pages, 7 figure
Rydberg Magnetoexcitons in CuO Quantum Wells
We present theoretical approach that allows for calculation of optical
functions for CuO Quantum Well (QW) with Rydberg excitons in an external
magnetic field of an arbitrary field strength. Both Faraday and Voigt
configurations are considered, in the energetic region of p-excitons. We use
the real density matrix approach and an effective e-h potential, which enable
to derive analytical expressions for the QW magneto-optical functions. For both
configurations, all three field regimes: weak, intermediate, and high field,
are considered and treated separately. With the help of the developed
approximeted method we are able to estimate the limits between the field
regimes. The obtained theoretical magneto-absorption spectra show a good
agreement with available experimental data