DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT

**Definition:** This place covers:

Devices using stimulated emission, for the generation or amplification of coherent electromagnetic waves or other forms of wave energy, e.g. masers, lasers, X-ray lasers, gamma lasers, optical amplifiers.

Constructional details or arrangements, e.g. housings, packages, cooling, electrodes.

Configuration of the resonators, or shape of the active media.

Processes or apparatus for pumping (exciting) said devices.

Such functions as modulating, demodulating, frequency-changing, controlling, or stabilising of said coherent electromagnetic waves, insofar these functions are performed by elements being part of the optical resonators or amplifier's arrangements; this includes particularly:

The special choice or adaptation of materials as active media.

Devices using non-linear amplification effects, e.g. stimulated Raman or Brillouin scattering

**Glossary:** - active medium: A medium providing for optical gain by the stimulated emission effect when excited by an excitation (pump) energy source. - laser: It is the acronym for "light amplification by stimulated emission of radiation" but it also refers, in broader sense, to any device using stimulated emission of radiation by excited atoms.Hence, for example, the expressions "semiconductor laser", "dye laser", "optical fibre laser" or "X-ray laser". - pumping: The process of providing the active medium for excitation energy.