Tuning electron bunch with a longitudinally shaped laser to generate half-cycle terahertz radiation pulse

Optical beat notes assisted attosecond soft X-ray pulse generation in high-gain free electron lasers

“…The wavelength of the seed laser is much shorter than the distance between the current spikes. Furthermore, we consider the case that two linear-chirped lasers are adopted to interact with the electron beam in the modulator with the central frequencies  can be expanded in Taylor series at 0  as [35],…”

“…Furthermore, we consider the case that two linearlychirped lasers are adopted to interact with the electron beam in the modulator with the central frequencies ω 1 and ω 2 . An unchirped laser passes through the dispersion component and the phase modulation φ (ω) can be expanded in the Taylor series at ω 0 as follows [36] :…”

“…Furthermore, we consider the case that two linearly-chirped lasers are adopted to interact with the electron beam in the modulator with the central frequencies and . An unchirped laser passes through the dispersion component and the phase modulation can be expanded in the Taylor series at as follows [ 36 ] : where the dispersion coefficient evaluates the m th derivative of with respect to . We consider the linear chirp and ignore the third and higher order terms of Equation (7).…”

Parabolic Mirror Focusing of Spatiotemporally Coupled Ultrashort Terahertz Pulses

“…Since the accelerator-based THz radiation is closely related to the characteristics of the electron beam, THz pulses with tunable frequency and high power can be obtained by modulating the electron beam. In previous studies [33], [34], an ultrashort strong-field THz radiation can be obtained by the modulated electron beam and matched undulator. The peak electric field can reach 60 MV/m with quasi sub-cycle oscillation as the gray line shown in Fig.…”

A Compact Accelerator-Based Light Source for High-Power, Full-Bandwidth Tunable Coherent THz Generation

“…Most of the FEL facilities adopt afterburners to generate intense THz radiation by using a compressed electron bunch with the duration shorter than one THz period; therefore, no high gain process is expected and the radiation power is usually limited to a maximal pulse energy of hundreds µJ (200 µJ [21] and 100 µJ [33]). Powerful narrow-band THz pulses can be produced by using a sub-picosecond (ps) scale pulse train, which can be generated either by directly illuminating the photocathode with a train of laser pulses [34][35][36] or manipulating the electron beam at relativistic energy (including exchanging transverse modulation to longitudinal distribution [37,38], direct modulating the drive laser [39], converting wakefield induced energy modulation to density bunching [40], two wavelengths of energy modulation in two separated undulator sections [41,42], slice energy spread modulation [43], and laser-based density modulation [44,45]). Comparing with the former method with the laser pulse train, the electron beam manipulation method has the advantage of more flexible tunability in the output frequency and can exclude the negative effects from the space charge force, which may smear out the longitudinal structures at low beam energy.…”