Misalignment sensitivity of beam combining by stimulated Brillouin scattering

Stimulated Brillouin scattering beam combining is shown to be extremely sensitive to optical misalignments. For the coupling of two overlapping beams, the angular misalignment bandwidth is of the order of 1 mrad, which corresponds to a separation of ±0.64 beam spot diameter. This occurs for beam displacements normal to the plane defined by the beams’ propagation paths.