Stimulated raman scattering in fiber-optic communication lines

Stimulated Raman scattering (SRS) in a long-distance fiber-optic communication line with wavelength-division multiplexing (WDM) is studied theoretically at a high power of the signal transmitted. A new criterion for determining the SRS threshold is used to calculate the critical input power versus the number of optical channels and frequency separation between them. The theoretical model is verified experimentally. SRS interaction between two channels in a communication line with an SRS amplifier for which the optical waveguide of the line serves as a nonlinear medium is measured.     

Thermal conductivity of indium at high pressures and temperatures under shock compression

The results of investigations of the electrical and thermal conductivity of indium in the pressure range up to 27 GPa and at temperatures up to 1000 K are presented. In this pressure range, the electrical resistance of indium samples is measured under multishock compression. The equation of state constructed for indium is used to calculate the evolution of the thermodynamic parameters of indium in shock wave experiments; then, the dependences of the electrical resistivity and thermal conductivity coefficient on the volume and temperature are determined. It is demonstrated that, in the pressure and temperature ranges under investigation, the thermal conductivity coefficient of indium does not depend on temperature and its threefold increase is caused only by the change in the volume under compression.     

Dynamic response of a mesoscopic antiferromagnetic particle to an ac magnetic field

Calculations are made for the dynamic susceptibility of a weakly ferromagnetic mesoparticle in the macroscopic quantum coherence region and the probability of conservation of the initial polarized state in a pulsed magnetic field. Fiz. Tverd. Tela (St. Petersburg) 39, 1240–1243 (July 1997)     

Equation of state of solids from high-pressure isotherm

A new variant of the method of finding the equation of state in the Mie–Grüneisen form is presented. It is based only on high-pressure isotherms of solids. Using this procedure, the semiempirical equation of state and shock adiabats of solids may be found at high pressures and high temperatures. The method is tested on periclase MgO within the range of shock pressures up to 300–500 GPa.     

Magnetic Transformations and Polymorphic Transition of Ferromagnetic Steels under Shock-Wave Loading

Technical Physics - A method for recording magnetic transformation is presented for ferromagnetic steels under shock-wave loading. The operation of the magnetic transformation gauge is considered...     

Thermal instability of glow discharge in the gas loop of CO2 laser with extended disk fans-heat exchangers

CO₂ lasers with transverse discharge and convective gas cooling find ever-increasing application. On strategy in making such lasers more efficient radiators is increasing the rate of the gas flow through the discharge zone with the help of diametral disk fans-heat exchangers. The application of such fans-heat exchangers, however, entails serious difficulties related to the glow discharge-gas flow interaction. In the present study, we investigate the stability problem for volume discharge in the gas loop of a CO₂ laser with diametral dis fans-heat exchangers.