Electron Beam Driven Generation of Frequency-Tunable Isolated Relativistic Subcycle Pulses

Abstract

We propose a novel scheme for frequency-tunable sub-cycle electromagnetic pulse generation. To this end a pump electron beam is injected into an electromagnetic seed pulse as the latter is reflected by a mirror. The electron beam is shown to be able to amplify the field of the seed pulse while upshifting its central frequency and reducing its number of cycles. We demonstrate the amplification by means of 1D and 2D particle-in-cell simulations. In order to explain and optimize the process, a model based on fluid theory is proposed. We estimate that using currently available electron beams and terahertz pulse sources, our scheme is able to produce mJ-strong mid-infrared sub-cycle pulses.

Coherent Diffraction Radiation of Relativistic Terahertz Pulses from a Laser-Driven Microplasma Waveguide

“…In particular, at high intensities, such pulses allow manipulation of the transient states of matter, for example giving control over the electronic, spin and ionic degrees of freedom of molecules and solids [5]. Several methods such as two-color laser filamentation [6], optical reflection in lithium-niobate [7,8] or organic crystals [9], and relativistic laser irradiated plasmas [10][11][12][13][14][15][16][17][18], have been developed for generation of THz pulses with electric fields above 1 MV/cm. However, scaling up such methods towards higher intensities remains challenging, thus representing an active research field.Relativistic electron beams have also been used to produce THz radiation through a variety of mechanisms that include synchrotron radiation [19], transition radiation [20,21], and diffraction radiation [22,23].…”

Laser wakefield driven generation of isolated CEP-tunable intense sub-cycle pulses

“…Such a nonstationary electron density structure can amplify a copropagating electromagnetic field. The energy density gain U gain of this electromagnetic field at any given point in space is described by [17]…”

“…On the one hand, this expression can be used with Maxwell's equations to derive the evolution equation for the vector potential [17,33]…”

“…On the other hand, the conservation of the transverse canonical momentum can be used to derive Eq. ( 1) describing the energy density gain of the seed pulse co-propagating with the non-stationary electron density structure [17].…”

“…mid-IR, single and sub-cycle pulses. We have shown that electron beams can be used to generate intense sub-cycle pulses by amplifying a seed pulse at a mirror foil [17]. Another technique to generate infrared, near-single-cycle pulses based on laser frequency down-conversion which is known to appear in laser-driven wakefields has been proposed in [18].…”