학술논문
Coherent soft X-ray pulses from an echo-enabled harmonic generation free-electron laser
Document Type
article
Author
Rebernik Ribič, P; Abrami, A; Badano, L; Bossi, M; Braun, HH; Bruchon, N; Capotondi, F; Castronovo, D; Cautero, M; Cinquegrana, P; Coreno, M; Couprie, ME; Cudin, I; Boyanov Danailov, M; De Ninno, G; Demidovich, A; Di Mitri, S; Diviacco, B; Fawley, WM; Feng, C; Ferianis, M; Ferrari, E; Foglia, L; Frassetto, F; Gaio, G; Garzella, D; Ghaith, A; Giacuzzo, F; Giannessi, L; Grattoni, V; Grulja, S; Hemsing, E; Iazzourene, F; Kurdi, G; Lonza, M; Mahne, N; Malvestuto, M; Manfredda, M; Masciovecchio, C; Miotti, P; Mirian, NS; Petrov Nikolov, I; Penco, GM; Penn, G; Poletto, L; Pop, M; Prat, E; Principi, E; Raimondi, L; Reiche, S; Roussel, E; Sauro, R; Scafuri, C; Sigalotti, P; Spampinati, S; Spezzani, C; Sturari, L; Svandrlik, M; Tanikawa, T; Trovó, M; Veronese, M; Vivoda, D; Xiang, D; Zaccaria, M; Zangrando, D; Zangrando, M; Allaria, EM
Source
Nature Photonics. 13(8)
Subject
Language
Abstract
X-ray free-electron lasers (FELs), which amplify light emitted by a relativistic electron beam, are extending nonlinear optical techniques to shorter wavelengths, adding element specificity by exciting and probing electronic transitions from core levels. These techniques would benefit tremendously from having a stable FEL source, generating spectrally pure and wavelength-tunable pulses. We show that such requirements can be met by operating the FEL in the so-called echo-enabled harmonic generation (EEHG) configuration. Here, two external conventional lasers are used to precisely tailor the longitudinal phase space of the electron beam before emission of X-rays. We demonstrate high-gain EEHG lasing producing stable, intense, nearly fully coherent pulses at wavelengths as short as 5.9 nm (~211 eV) at the FERMI FEL user facility. Low sensitivity to electron-beam imperfections and observation of stable, narrow-band, coherent emission down to 2.6 nm (~474 eV) make the technique a prime candidate for generating laser-like pulses in the X-ray spectral region, opening the door to multidimensional coherent spectroscopies at short wavelengths.