Beam Combining With Using Beam Shaping

Performance of spectral beam combining depends on thermal effects on the optical components like volume Bragg gratings used for spectral selectivity of the beams combined. These thermal effects are results of absorption of laser radiation and in case of high power lasers can lead to reduction of efficiency of combining and losses. For example the Gaussian intensity distribution of laser beam leads to higher temperature in the central part of a grating and, hence, changing its operating specifications. Homogenizing of the temperature profile over the working field of a volume Bragg grating would increase efficiency of its operation. This can be realized through applying the beam shaping optics, for example refractive field mapping beam shapers providing high flexibility in building various optical setups due to their unique features: almost lossless intensity profile transformation, providing flattop, super Gauss or inverse Gauss profiles with the same beam shaper, saving of the beam consistency, high transmittance and flatness of output beam profile, extended depth of field, capability to adapt to real intensity profiles of TEM00 and multimode laser sources. This paper will describe some design basics of refractive beam shapers of the field mapping type, with emphasis on the features important for building and applications of high-power laser sources. There will be presented results of applying the refractive beam shapers in real research installations. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE)