New 2.7 micron Fiber Laser for Space Laser System Cost Reduction

"This proposal describes the development of a new diode-pumped fiber laser intended as an alignment tool for the High Energy Chemical Laser (HEL) during startup and optical alignment. This alignment laser, also called the Low Energy alignment Laser (LEL),will be fabricated from a special double-clad glass fiber, in a configuration designed to enable very efficient optical pumping by a low-cost diode laser. Such fiber lasers have exhibited nearly single-transverse-mode output at 2.7 microns. The advantageof this fiber laser over currently available 2.6 - 2.9 micron alignment lasers (such as diode-pumped solid-state lasers pumping periodically poled lithium niobate crystals) lies in its simplicity and reduced cost. Phase I of the proposed project willfocus on design and evaluation of diode-pumped fiber lasers, using commercially-available diode pump lasers which will be fiber coupled into several different fiber configurations. The fiber laser emission and beam quality will be characterized. Phase IIwill focus on further improving laser performance and completion of the design, fabrication, demonstration, and delivery of a prototype LEL unit. Coinciding with strong water absorption in this spectral region, this fiber laser also presents abreakthrough for medical applications. Use of a mid-IR fiber laser in place of currently-used mid-IR optical parametric oscillators for the LEL of the space-based HEL system will reduce system c