An optical amplification system directs a diffraction-limited signal beam through a series of approximately 90.degree. crossings with a number of non-diffraction-limited pump beams in a photorefractive medium. All of the beams are s-polarized, resulting in an energy transfer from the pumps to the signal beam while leaving the signal beam diffraction-limited. The photorefractive medium is preferably a series of BaTiO.sub.3 :Rh crystals that receive the pump and signal beams through orthogonal faces, with their C-axes at approximately 45.degree. to both beams. A binary tree optical distribution network is used to minimize waveguide splits in forming a large number of pump beams. The outputs of several amplification modules are combined into a single output beam using adaptive optics, with the outputs from the different modules phase matched to each other by diverting two minor portions of the combined beam, partially overlapping the diverted beams and adjusting the amplification module phases to cancel phase differentials between the overlapped portions. Similarly, sets of combined and phase-matched beams can be combined with each other (again using adaptive optics) to generate still higher powers using a super module approach.