title: Spectral modulation of higher harmonic spontaneous emission from an optical klystron.
abstract: Higher harmonics of spontaneous emission from an optical klystron have been observed. The modulation factor of the spontaneous emission spectrum for the higher harmonics can be described by considering the observation system. When the dispersive gap of the optical klystron was fixed, the microstructure interval of the spontaneous emission spectrum at a certain resonant wavelength became narrower as the order of the higher harmonic became larger. Some unique characteristics of the higher harmonics have been clarified, and these studies are likely to contribute to the development of free-electron lasers using higher harmonics of an optical klystron in the shorter-wavelengths region.
authors: Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors: Norihiro
authors: N
authors: Sei
authors: Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors: Hiroshi
authors: H
authors: Ogawa
authors: Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors: Kawakatsu
authors: K
authors: Yamada
authors: Research Institute of Instrumentation Frontier, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
authors: Masaki
authors: M
authors: Koike
authors: Institute of Advanced Energy, Kyoto University, Gokanosho, Uji, Kyoto 611-0011, Japan.
authors: Hideaki
authors: H
authors: Ohgaki
keywords: free-electron laser; higher harmonic; optical klystron; spectrum; spontaneous emission