title: Development of high-throughput, high-damage-threshold beam separator for 13 nm high-order harmonics.
abstract: We demonstrate a high-throughput, high-damage-threshold beam separator for wavelengths shorter than 30 nm, which uses a 10 nm thick niobium nitrogen film prepared on a Si substrate, set at the Brewster angle relative to the pump wavelength. The film was deposited by rf reactive magnetron sputtering on a Si substrate. The beam separator has an attenuation ratio of 0.01 and a damage-threshold intensity of at least 0.8 TW/cm2 for a 26 fs pump pulse. The measured reflectivity of the beam separator exceeded 70% in a wavelength range of 13-18 nm. This broadband beam separator may be used to eliminate energetic laser pulses from longitudinally pumped x ray lasers as well as from high-order harmonics.
authors.affiliation: Laser Technology Laboratory, Saitama, Japan. ynagata@riken.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nagata
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nabekawa
authors.forename: Katsumi
authors.initials: K
authors.lastname: Midorikawa