Evidence for competition modes in a partially guided far-infrared free-electron laser

Abstract

The infrared free-electron laser (FEL) offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adapting the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before, a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different transverse sizes. A good agreement is found with results of simulations and with a simple analytical formula.

Fully 3D time-dependent simulation of free electron laser within an overmoded rectangular waveguide

“…(2.1)), Prazeres has developed the numerical method using the fast Fourier transform [18,23,24] similar with the waveguide mode decomposition. Based on the numerical simulations, the spectral gaps phenomenon observed by the FEL oscillators were successfully explained [25][26][27]. To make a comparison, we use the same parameters as ref.…”

“…The waveguide effect on FEL has been studied by a number of authors [2][3][4][5][6][7][8][9][10][11][12][13]. In a waveguide FEL, the radiation field propagates inside the waveguide as waveguide modes, not like a light flux in a free space FEL.…”

Design of FELiChEM, the first infrared free-electron laser user facility in China

“…8, the waveguide enhances the small signal gain by more than two times. In addition, according to the operation experience of CLIO and FE-LIX [22,23], "spectral gap" may appear in this waveguide FEL, and we are now considering this problem for FELiChEM.…”

Analysis of high order dispersion effects on a beat frequency-based THz free-electron laser

“…[1][2][3] In the last decades, accelerator-based THz radiation have been used in nonlinear responses in matters, spectroscopic application and time-resolved applications. [4][5][6][7][8][9][10][11][12][13] which employs the THz radiation as a nonionizing probe. THz radiation are expected to enable more fascinating scientific applications, such as single-shot THz bioimaging, THz-triggered chemistry and ultrafast magnetic switch, which requires coherent THz pulses with pulse energy at millijoule (mJ) level and tunable frequency up to tens of THz.…”