Active optical elements include devices whose operating principle is based on the interaction of at least two light fluxes in an active medium. These elements include:

    - optical amplifiers,
    - optical wave converters.

Optical amplifiers
Optical amplifiers increase the power of a signal without converting it into electrical form. They work on the basis of the principle of stimulated emission, like specialized forms of lasers that amplify light in a single pass through an amplifier. Currently, two main types of optical amplifiers are used: fiber based amplifiers with additives and semiconductor laser amplifiers.

Wave convectors
In the framework of the concept of fully optical networks, the wave converter implements the optical conversion of the wavelength into a signal passing into a different wavelength, which is necessary for switching the signal in multi-channel communication lines with wavelength division multiplexing. The principle of operation of such a conversion, also known as λ-conversion, based on the effects of nonlinear interaction of the original optical signal with a special signal from the pump laser, resulting in the formation of a new wavelength radiation. This conversion, unlike optoelectronic conversions, does not introduce a delay and is capable of operating up to very high modulation frequencies (10 Gbit / s and higher).