Editing Laser (section)

=== Free-electron lasers ===
[[File:FELIX.jpg|thumb|The free-electron laser ''FELIX'' at the FOM Institute for Plasma Physics Rijnhuizen, [[Nieuwegein]]]]

[[Free-electron laser]]s (FEL) generate coherent, high-power radiation that is widely tunable, currently ranging in wavelength from microwaves through [[terahertz radiation]] and infrared to the visible spectrum, to soft X-rays. They have the widest frequency range of any laser type. While FEL beams share the same optical traits as other lasers, such as coherent radiation, FEL operation is quite different. Unlike gas, liquid, or solid-state lasers, which rely on bound atomic or molecular states, FELs use a relativistic electron beam as the lasing medium, hence the term ''free-electron''.