Combining novel highly-doped phosphate glasses and advanced fiber drawing techniques, we fabricated and tested single-frequency fiber lasers that generate powers of more than 2-W. We demonstrate enhanced performance employing active photonic crystal fiber compared to more conventional devices that are based on large core step-index fiber.
Through the integration of phosphate glass fiber gratings and highly-doped active phosphate glass fiber, we improve on optical, thermal, and mechanical behavior of our compact fiber lasers. Powerful and widely tunable phosphate glass distributed fiber lasers are presented and the possibility of cascading several grating structure for multiple wavelength generation is demonstrated. We also present results on phase-locking and coherently combining the output of up to 37 fiber cores into a single, near-Gaussian laser beam. To achieve exclusive oscillation of the fundamental in-phase supermode, several all-fiber laser cavities have been designed, numerically analyzed, fabricated, and tested. We will report on a 10-cm long monolithic all-fiber laser that emits more than 12-W of optical power and is based on combining the output of 19 active cores. All the cores are integrated within the same cladding and arranged in a two-dimensional isometric array.