An improved tube solid-state laser (SSL) is provided utilizing diode pumping, microchannel cooling, optics, and/or new coating and bonding processes. In one example, an amplifier module for the SSL includes a tube of laser gain material, a first substrate and a second substrate including microchannels adjacent an interior and exterior surface of the tube, respectively, and a plurality of diode bars arranged exterior to the second substrate. Advantageously, thermal lensing effects, birefringence, bifocussing, and alignment problems associated with typical tube SSLs are eliminated or reduced while providing high beam quality and high average power levels.