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The features of Raman lasing and generation bandwidth in SiO2TiO2 single-mode fiber are analyzed. The spectroscopic method for determination of the Raman gain profile from the spontaneous Raman cross-section in TiO2 doped fiber is proposed. Numerical results on lasing band and Raman gain threshold in TiO2 doped single-mode fiber is presented. It is shown the TiO2 lasing band may be almost twice wider...
Electromagnetic wave destruction due to photon-phonon interaction (polariton) in the negative dielectric band of crystal has been studied in our work. General case without low damping approximation is considered. Modeling results are obtained in analytical form based on single oscillator model. Phonon damping effects are analyzed using the new common technique of the phase portraits both for complex...
Research results of deep minima reflectance of terahertz (far-infrared) radiation one may observe experimentally in a number of crystalline media are firstly presented in the paper. Analysis of physical conditions for the almost complete disappearance of the electromagnetic waves reflection from the interface with crystal is given. We based on single oscillatory model of crystal and it allows us to...
The physical conditions analysis for the appearance of negative values of the dielectric function (DF) within the T-L splitting frequency interval in polar crystals is presented. The simple quantitative criterion for existence of negative DF band is derived in the three equivalent forms as a proper combination of basic parameters of a single phonon vibration. Principal significance of the phonon damping...
Analytical expression of wavelength dependence of signal attenuation coefficient in the range of S+L+C telecommunication window is obtained using polynomial approximation in single-mode silica fibers: DCF, TrueWaveRSTM and pure SMF. It allowed correcting the threshold conditions of Raman amplification. It is shown that Raman gain threshold increased adjusted for wavelength irregularity of attenuation...
Anisotropy effects on the negative dielectric permittivity (DP) formation in the frequency region near the phonon lattice vibrations are considered using three crystalline modifications of boron nitride. Quantitative data on frequency intervals and negative DP values are presented for all anisotropic modifications. It is shown that anomalous dispersion of the refractive index falls to 0 <...
Damping of the polar vibrations determines the real limits of negative dielectric permittivity (DP) region as shown in this work. We obtain the simple quantitative criterion for the negative DP existence in the single oscillatory approximation model. We introduce this criterion as inequality between the damping constant and T-L frequency splitting of the polar phonon. This inequality is the sufficient...
Terahertz anomalous dispersion and material physical properties leads to form the region with negative dielectric permittivity (DP) that is created around the polar frequency oscillations in three crystalline modifications of boron nitride will be analyzed in our report. Our analysis based on the simple quantitative criterion of existence the negative DP bands. Seven vibrations in different crystalline...
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