title: Second harmonic FEL oscillation.
abstract: We have produced and measured for the first time second harmonic oscillation in the infrared region by a free electron laser. Although such lasing is ideally forbidden, since the gain of a plane wave is zero on axis for an electron beam perfectly aligned with a wiggler, a transverse mode antisymmetry allows sufficient gain in this experiment for lasing to occur. We lased at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM01 mode.
authors.affiliation: Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA. neil@jlab.org
authors.forename: G R
authors.initials: GR
authors.lastname: Neil
authors.forename: S V
authors.initials: SV
authors.lastname: Benson
authors.forename: G
authors.initials: G
authors.lastname: Biallas
authors.forename: J
authors.initials: J
authors.lastname: Gubeli
authors.forename: K
authors.initials: K
authors.lastname: Jordan
authors.forename: S
authors.initials: S
authors.lastname: Myers
authors.forename: M D
authors.initials: MD
authors.lastname: Shinn