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The influence of In surface segregation and internal fields induced by polarization charges on the band structure on InGaN/GaN quantum wells is studied in the frame of 6×6 multiband model. The indium surface segregation leads to the blue shift of the transition energy (70 meV for the segregation length 1nm at both heterointerfaces) while the piezoelectric polarization itself causes the red shift....
As-grown ZnO:In crystalline plates demonstrate strong near-band-edge emission related to exciton recombination (380 nm - free excitons; 395 and 406 nm - excitons localized in the impurity centers). Fabry-Perot mode structure is observed for last two bands. Dramatically increasing narrow line (396 nm, Δλ ~ 3.3 nm) is connected with EHP recombination.
The main requirements for the MCT (CdxHg1-xTe) structures optimization for increase of the stimulated emission wavelength under optical pumping are discussed. The stimulated emission at wavelengths 2-2.5 μm at room temperature from optimized MCT structures is observed experimentally. The obtained experimental data are the first observation of stimulated emission from the MCT structures at these wavelengths...
Two types of superluminescent diodes (SLDs) based on DQW (InGa)As/(GaAl)As/GaAs nanostructures with 25 μm-width multimode active channels emitting at 890 nm and 950nm were studied. They ensure CW optical power of more than 100 mW ex standard 50 μm multimode fiber (MMF).
The experimental results causing the trench of subwavelength nanostructures formation in semiconductor's 4H-SiC surface and inside volume along the femtosecond beam path are considered. The given qualitative explanation of the observed phenomenon is based on universal polariton model of laser-induced material damage with extension of excitation the cylindrical surface plasmon polaritons and their...
Stimulated emission from quantum dots arrays has been observed under optical pumping. The emission has been observed from the ground state for electrons (λ ≈ 1.31 μm) and from two higher levels (λ ≈ 1.21 μm, 1.12 μm). The measured values of the amplification coefficient are rather high, up to 15 ÷ 17 cm-1. Procedure of the amplification coefficient measurements in the active media has been discussed.
Temperature dependences of electron threshold current density in ZnSe-based laser heterostructures for the temperature range of 12-300 K and electron energies of 3.5-8.1 keV have been studied in detail. The minimum value of threshold current density of 0.2 A/cm2 has been measured at the electron energy E = 8 keV and temperature T = 50 K. The analysis of experimental and simulated data indicates on...
Numerical calculations of energy characteristics of quantum-well structures based on Si1-xGex-Si have been performed using the four-band k·p method. It is shown that varying the thickness of the active layer and the height and width of potential barriers one can control the frequency ω of optical transitions. The analytical expressions for ħω are established, which are in good agreement with the numerical...
Asymmetric multiple quantum well active regions for optically-pumped semiconductor disk lasers (OPS-DLs) are designed employing wave function engineering within GaAs/AlGaAs material system, which provide simultaneously good electronic confinement, large gain and effective carrier transport. Experimental investigation has shown that such an approach gives record values of the conversion efficiency...
A method of the coherent near-field sounding of multilayered dielectric structures is studied. It is based on field measurements with subwavelength probes (emitting and receiving) that are spaced in the near-field zone above the upper layer of the studied structure. It makes possible to achieve a subwavelength resolution at the control of the layers' depth. Especially high resolution can be achieved...
In this paper we investigate the field propagation characteristic in new type new optical waveguides, made of glasses and noble metals. The proposed waveguide, having nanosize cross-section, supports propagation of modes with unusual propagation properties. The propagation speed, attenuation and field localization of those modes will be present. The proportional reducing of the coaxial scale have...
Spectral characteristics of the microcavity based on a free-standing mesoporous silicon layered structure containing nematic liquid crystal E7 are studied. Nonlinear thermal tuning of resonant peak position has been realized by both conventional and laser heating. In both cases reversible tuning is observed within 11 nm range. Laser beam with power of 100 mW provides total tuning of the microcavity.
Nanosize thin flat silver strip in the air is considered as an optical resonator. The scattering characteristics of the H-polarized electromagnetic wave diffraction are analyzed using the decoupled singular and hyper-singular integral equations (IEs) for the electric and magnetic surface currents on the strip. IEs are discretized with the aid of the interpolation type quadrature formulas. This algorithm,...
Spontaneous emission of a quantum dot placed in a 1D photonic band gap structure is analytically studied. Part of energy which remains nonradiated is obtained. It is shown that decay first follows ~t-1/2 law changing to ~t-3/2 law. Analytical expression for the spectrum is obtained. Analytical theory of the Borrmann effect is developed.
Using the field expansions in local coordinates and addition theorems for cylindrical functions, we consider the problem of the H-polarized plane wave scattered by a finite chain of circular wires. The absorption and scattering cross-sections are found numerically and plasmon and grating-type resonances are studied for the grids of silver nano-size wires.
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