Lasers with polyhedral energy guides

New laser resonators, called energy guides, are described. These energy guides are small, but the path traveled by the radiation interacting with the active material is long. The use of such guides makes it possible to reduce the size and improve the parameters and the reliability of laser systems. A description is given of a method for the design of energy guides. Examples of design calculations are reported and a guide made of neodymium glass is described. The results of preliminary experiments are reported. It was found that although a neodymium-glass energy guide was small the active path of the radiation could be up to 2.5 m long. The use of this guide reduced the excitation threshold, improved the mode structure, and reduced the divergence of the laser beam.