Description: Freedom Photonics proposes the development of watt-class diffraction-limited diode lasers with extremely high reliability for pumping solid state lasers. Two target operating wavelengths will be pursued, 808 nm and 885 nm, in order to support the two common pump bands for Nd:YAG microchip lasers. Diffraction-limited pump diodes enable close matching of the end-pumped gain region to the fundamental cavity mode of the solid state laser. This approach improves the laser efficiency, power, beam quality, and reliability, all of which are critical for space-based LIDAR systems. In Phase 1, Freedom Photonics demonstrated 885 nm diffraction-limited lasers with >1.8 W output power and excellent robustness. These results were enabled by laser epitaxial designs with extremely high efficiency and facets robust to catastrophic optical mirror damage by means of advanced passivation technology. In Phase 2, the operating power and efficiency will be further improved, and these diffraction-limited pump lasers will also be scaled to an emission wavelength of 808 nm. Reliability and environmental testing will be carried out to demonstrate compatibility with space flight operation. Spectral narrowing and wavelength stabilization will allow for maximum pump absorption without the need for strict control of the diode junction temperature.

Benefits: There are several NASA applications which will benefit from our proposed work. The first use is for pumping the seed laser in the Laser Interferometer Space Antenna (LISA) space-based gravitational wave observatory. These pump diodes will also find use in LIDAR systems for remote sensing and guidance and navigation systems. High power, narrow linewidth diodes in this wavelength range are also critical for laser-based gyroscopes for inertial sensing and atomic clocks.

1) Seed sources for high energy solid state and fiber lasers 2) Pump sources for high energy solid state and fiber lasers 3) Pulsed laser sources for marking 4) LIDAR systems for remote sensing 5) 3D imaging systems for autonomous vehicles 6) Trace gas detection 7) Direct diode sources for high energy lasers