Amplification of light in inhomogeneous waveguides with an adjacent active medium

An investigation was made of the characteristic features of the amplification (absorption) of modes in inhomogeneous optical waveguides with an adjacent active medium. The WKB approximation was used to derive equations for the calculation of the gain (absorption coefficient) of modes in waveguides with different refractive index profiles. It was found experimentally and theoretically that the gain (absorption coefficient) of modes in inhomogeneous waveguides could be made close to the gain (absorption coefficient) of the adjacent active medium.