Compact Tunable Infrared Grating Laser

A Phase I SBIR study is proposed of a novel infrared laser configuration employing a coaxial resonant structure and a gyrating electron beam. The center conductor of the structure contains axial ridges that support diffraction radiation induced by the axis-encircling gyrating beam, while the outer conductor of the structure supports radial standing waves that provide feedback to sustain oscillations. The electron beam is to be provided by a recently developed industrial gun that can furnish up to 1 megawatt of high quality beam power at a voltage of up to 100 kV on thin axis-encircling orbits in a moderate guide magnetic field. This novel concept has the potential of providing a compact, voltage-tunable, multi-kilowatt, high duty cycle, coherent, infrared source in the 50-200 micron wavelength range suitable for a variety of civilian and military applications. The proposed Phase I study involves linear and nonlinear theory and numerical simulations to allow design of the structure and its incorporation with the industrial electron gun. Means to maximize the voltage-tunable bandwidth and efficiency will be studied. Results of the Phase I study are to be organized to lead to a Phase II experimental demonstration of the compact tunable infrared grating laser.