Coherent thulium-doped double clad fibers utilize glass compositions specifically optimized for high degree of cross-relaxations between Tm ions enabling efficient conversion of 793 nm pump photons into signal photons at 2 µm. The precision matched -M fiber version offers even higher absorption and efficiency than the -HE version. In addition, the waveguide design in the -M version is specifically tailored to offer a truly single-mode operation in monolithic fiber laser/amplifier systems when spliced to the precision matched passive fibers. These fibers, along with matching passive fibers, are available in 130 µm cladding diameter for ease of handling, cleaving and splicing, enabling reliable manufacturing of low power, eye-safe, fiber lasers and amplifiers.