Aspects of embodiments pertain to beam combining devices for coherent and spectral beam-combining. The coherent beam combining (CBC) device may comprise a monolithic body having an input surface and an output surface. The input surface may be configured to direct a plurality of coherent entering optical beams through an optical pathway inside the monolithic body towards the output surface; and a phase mask configured for combining beams, exiting from the output surface of the monolithic body, to form a single combined output beam. The Spectral beam combining (SBC) device may include a monolithic body configured to direct the entering optical beams through a multi-diffraction optical pathway inside the monolithic body by directing the entering optical beams such as to impinge a diffractive surface thereof at least twice, for combining the entering optical beams into a single multispectral combined output optical beam. Embodiments may also include methods for cascaded beam combining, using multiple combining devices in a network configuration.