High power CW solid-state multilaser system I. PESHKO, G. GALICH, M. LOPIYCHUK, A. KHIZHNYAK, V. NAKVASUK
A laser system containing four CW Nd : YAG double-rod lasers, transforming optics and a fibre with input-output optics has been designed and investigated. It is shown that reduction of the beam parameter product of the non-Gaussian beams in the image space of the lens has made it possible to collect the emission of four lasers to the same fibre. Independent laser operation has provided the output power control in the range of IO-900 W with a stable light spot size on the input end of the fibre. @ 1997 Elsevier Science Ltd. KEYWORDS: lasers (Nd : YAG), beam parameter product, fibre
Technological solid-state lasers: achievements and problems
Today, high power CW solid-state lasers achieve some kW of output power. Such lasers are used for technological purposes such as instruments for welding, cutting, and drilling of metal sheets some centimetres thick. In spite of the great success of the diode pumped Nd : YAG lasers in the l-5 kW power range, the lamppumped systems remain more practically used'. Because of their relatively low efficiency (about 3-5%) these lasers need significant levels of input power. As a result, the cooling system has to be very efficient. Usually, a two-circuit water-cooling system is used, which needs the additional expenditure of electric power and distilled water. However, such lasers are quite attractive from many points of view. Their relatively compact size and solid-state design make them easy to include into most technological systems. The volume size of a modern 1 kW-class solid-state laser is only about 0.5 m3. The wavelength of a YAG laser is near 1 urn, which potentially allows one to realize fine focusing of emission and to achieve a CW power density of lo7 W cmm2. At this wavelength a modern fibre has losses of some dB per km. The output optics design is light enough to be driven by a three-dimensional moving system with fine accuracy. The apparatus for welding in difficult and inaccessible places, for example inside the boiler of an atomic power station, may be constructed and manufactured.