Pulse-front tilt caused by spatial and temporal chirp

Abstract

Pulse-front tilt in an ultrashort laser pulse is generally considered to be a direct consequence of, and equivalent to, angular dispersion. We show, however, that, while this is true for certain types of pulse fields, simultaneous temporal chirp and spatial chirp also yield pulse-front tilt, even in the absence of angular dispersion. We verify this effect experimentally using GRENOUILLE.

Theory of terahertz generation by optical rectification using tilted-pulse-fronts

“…An optical pulse with a TPF is typically angularly dispersed [17]. Therefore, various frequency components of the emergent optical field described by 0 0 ( , , )…”

“…This is tantamount to having different spectral bandwidths, pulse durations and average frequency at each spatial location. These effects are termed spatio-temporal distortions [17] and affect the properties of the generated THz radiation. Secondly, since the generated THz propagates perpendicular to the TPF, the optical pump and THz radiation propagate non-collinearly.…”

Diagnostics and controls for spatiotemporal couplings for laser-plasma accelerator drivers

“…For a common doublepass optical compressor, non-parallel gratings introduce angular dispersion, and the misaligned retro-reflection mirror introduces spatial chirp [17]. Spatial chirp can also be introduced by propagating a pulse with angular dispersion [18]. Angular dispersion, ψ, from a common optical compressor is described as [19], 110008-1 where subscript n denotes "near-field", θ is the laser propagation angle, λ the laser wavelength, N the grating groove density, α the incident angle to the grating, β the diffraction angle at the grating, and δ g the misaligned angle of the grating pair.…”

“…Spatial chirp is commonly measured with an imaging optical spectrometer. A shear in the GRENOUILLE image [22] and PFT caused by spatial and temporal chirp [18] can also be used to measure spatial chirp. Spatial chirp can be defined as the frequency gradient ξ = dω 0 /dx, where ω 0 is the mean angular frequency at position x, and introduces PFT as [18],…”

Pulse-front tilt for short-wavelength lasing by means of traveling-wave plasma-excitation

“…The basic idea integrates with existing components of a common pump systems for realizing ASE lasing. In fact, in chirped-pulse amplification (CPA) a stretched pulse is amplified and then recompressed using a grating pair (compressor) [5][6][7][8][9]. The two compressor gratings must be perfectly parallel to achieve optimum recompression over the entire beam diameter.…”