A method for 
laser diode bar 
assembly. A method for assembling a modular stacked 
diode array is disclosed, whereby a 
diode bar is bonded between a pair of conductive spacers, as by 
soldering, to create a diode submodule. Each submodule, prior to being affixed to a substrate, may be individually pre-tested. Any number of diode bar submodules then may be affixed to a substrate to construct a diode bar array. A stacked array embodiment assembled according to the method provides for efficient cooling of the diode bars and 
electrical connection between diode bars while maximizing alignment of the diode bars. The spacers are connected to a conductive surface on a 
heat spreader. In the stacked array, one or more diode bars are alternated in series with two or more conductive spacers, with a series circuit provided from diode bar to diode bar. The spacers hold the diodes spaced apart from insulating grooves in the conductive layer on the substrate. Alternatively, thermally conductive separator fins extend from the 
heat spreader substrate to contact the diode bars situated between the spacers to promote rapid 
heat transfer from the diodes while maintaining the diode bars electrically isolated from tie conductive layer on the substrate.