Change of light colour by a layer with moving boundaries

It is shown that high effectiveness in altering the amplitude and frequency of an electromagnetic wave can be achieved by a combination of two mechanisms. Two examples of such combination are considered. The first one is approaching movement of medium boundaries accompanied by iterative multiple reflections. This process generates electromagnetic pulses with infinitely increasing carrier frequency and field energy. The second example concerns a reflection of an electromagnetic wave from plasma that moves in a waveguide where a high reflectivity is attained for a small value of the boundary velocity owing to the double dispersion mechanism.