Free-electron lasers

Abstract

Free-electron lasers (FELs) are lasers that use an electron beam from an accelerator to produce widely tunable, high power, ultrafast pulses of coherent radiation. FELs are today important sources of infrared and far-infrared radiation around the world. Quasi-CW high-power FELs are also operational. FELs that operate on the self-amplified spontaneous emission principle are leading candidates for X-ray lasers and fourth-generation light sources. We discuss the physics, technology, advantages and applications of FELs, and explore the frontiers of X-ray and high-power FELs. We also present details of plans for a compact, ultrafast, terahertz free-electron laser in India.