Infrastructure-grade, high-power laser for free-space optical power delivery

Free-space optical power delivery, transmitted from orbit, can be an attractive option for in-space and high-altitude customers if power-levels on the order of 100kW to 1MW can be transmitted continuously over ranges greater than 1,000km using utility-grade infrastructure (i.e., 20+ year service life with little or no maintenance). A Tiled Aperture Photonic Crystal Surface Emitting Laser (TAPCSEL) is a strong candidate to meet these requirements if a range of engineering challenges can be overcome. The TAPCSEL addresses PCSEL power scaling in a new way, forming a large area scalable array of isolated PCSELs bound by mirror elements. In this approach, only sufficient power to realize wavelength and phase locking is passed between TAPCSEL elements, and in-plane parasitic loss is eliminated. We present outlines of this approach and provide a summary of work to date on design, implementation, and on future challenges. Our laser emitter, aptly named SLEM for scalable laser emitter and its flat-panel form factor, is composed of a TAPCSEL and a Diamond-Evaporator Heat Exchanger (DEHX) to uniformly cool TAPCSEL. SLEM is a direct laser that, if successful, will implement free-space coherent beam combining among thousands of PCSELs that mode lock without external optics or control electronics.