High Power, Narrow Linewidth 2-micron Diode Laser Sources

High power mid-IR amplifiers based on Thulium or Holmium doped fibers typically require a narrow spectral linewidth source to serve as the seed laser. While conventional injection seeding sources (such as DFB diode lasers and rare-earth doped solid-state microchip lasers) are available at 1.5 microns, similar sources which operate at 2.0 microns are not. In order to fill this need, nLight proposes the development of high power, narrow linewidth 2.0 micron diode laser seed sources based on our well-established, wavelength-scalable, industry-leading InP semiconductor laser design. Optical feedback provided by external fiber Bragg gratings serves to narrow the semiconductor linewidth to the appropriate level. These lasers are expected to deliver very high seed power (>250 mW) at 2.0 microns with a spectral linewidth less than 10 MHz. The external feedback approach will allow the linewidth to be easily tailored to meet the individual needs of varying applications, increasing the commercial relevance of the proposed approach. At the end of the proposed Phase 1 effort (and at the request of the MDA), prototype narrow-linewidth 2.0 micron lasers will be packaged, efficiently coupled to single mode fibers, and delivered to the MDA or a recipient of their choosing