We study the energy loss and gain of heavy quarks in a hot thermal medium. These include change due to polarization interaction with fluctuations The dynamics medium is described by Wong equations, that allow for inclusion both backreaction on medium, gluon field. Both momentum as well temperature dependence charm bottom quark are studied. find dominate at high-temperature domain achievable ear...

The propagation of surface plasmon polaritons on metallic waveguides adjacent to a gain medium is considered. It is shown that the presence of the gain medium can compensate for the absorption losses in the metal. The conditions for existence of a surface plasmon polariton and its lossless propagation and wavefront behavior are derived analytically for a single infinite metal-gain boundary. In ...

Erbium-doped fiber is a gain medium exhibiting homogeneous line broadening at room temperature, while a semiconductor optical amplifier has a dominant feature of inhomogeneous line broadening. In this work, a semiconductor optical amplifier is incorporated into the cavity of an erbium-doped fiber ring laser to form a hybrid gain medium. Theoretical analysis shows that such a gain medium support...

Total internal reflection occurs for large angles of incidence, when light is incident from a high-refractive-index medium onto a low-index medium. We consider the situation where the low-index medium is active. By invoking causality in its most fundamental form, we argue that evanescent gain may or may not appear, depending on the analytic and global properties of the permittivity function. Fo...