title: Near-threshold harmonics from a femtosecond enhancement cavity-based EUV source: effects of multiple quantum pathways on spatial profile and yield.
abstract: We investigate the photon flux and far-field spatial profiles for near-threshold harmonics produced with a 66 MHz femtosecond enhancement cavity-based EUV source operating in the tight-focus regime. The effects of multiple quantum pathways in the far-field spatial profile and harmonic yield show a strong dependence on gas jet dynamics, particularly nozzle diameter and position. This simple system, consisting of only a 700 mW Ti:Sapphire oscillator and an enhancement cavity produces harmonics up to 20 eV with an estimated 30-100 μW of power (intracavity) and > 1μW (measured) of power spectrally-resolved and out-coupled from the cavity. While this power is already suitable for applications, a quantum mechanical model of the system indicates substantial improvements should be possible with technical upgrades.
authors.affiliation: Department of Physics and Astronomy, University of British Columbia,Vancouver, British Columbia, Canada
authors.forename: T J
authors.initials: TJ
authors.lastname: Hammond
authors.forename: Arthur K
authors.initials: AK
authors.lastname: Mills
authors.forename: David J
authors.initials: DJ
authors.lastname: Jones
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D008962:Models, Theoretical; D055096:Optical Devices; D011789:Quantum Theory; D012542:Scattering, Radiation