This Phase I effort seeks to develop DFB laser master oscillators at the novel wavelength of 12050 nm. Two prototypes will be built, tested, and delivered . Currently, DFB laser chips are not available COTS at this wavelength. However, EM4 has identified a stock of devices that may be used for initial proof-of-concept testing. Due to the very large size of optical isolators at this wavelength, an isolator will not be included in the package.