In situ frequency gating and beam splitting of vacuum- and extreme-ultraviolet pulses

Abstract

Monochromatization of high-harmonic sources has opened fascinating perspectives regarding time-resolved photoemission from all phases of matter. Such studies have invariably involved the use of spectral filters or spectrally dispersive optical components that are inherently lossy and technically complex. Here we present a new technique for the spectral selection of near-threshold harmonics and their spatial separation from the driving beams without any optical elements. We discover the existence of a narrow phase-matching gate resulting from the combination of the non-collinear generation geometry in an extended medium, atomic resonances and absorption. Our technique offers a filter contrast of up to 104 for the selected harmonics against the adjacent ones and offers multiple temporally synchronized beamlets in a single unified scheme. We demonstrate the selective generation of 133, 80 or 56 nm femtosecond pulses from a 400-nm driver, which is specific to the target gas. These results open new pathways towards phase-sensitive multi-pulse spectroscopy in the vacuum- and extreme-ultraviolet, and frequency-selective output coupling from enhancement cavities.

Efficient extreme-ultraviolet multi-band high-order wave mixing in silica

“…14,15 As HHG finds its way into industrial applications, 18,19 the requirement to improve its conversion efficiency to levels that enable robust applications, has led to deeper understanding of how multi-color drivers increase the brightness of HHG sources. [19][20][21][22][23] SSHHG is characterized by the choice of the driving field and generation material, which profoundly influence the generation mechanism. The leading causes for high-harmonic emission from solids discussed in the literature are on the one hand nonlinear intraband currents, that are created by strong-field carrier acceleration following excitation at the Γ-point, 1,3 and on the other hand electron-hole recollisions after carrier acceleration away from the Γ-point.…”

Realisation and optical engineering of linear variable bandpass filters in nanoporous anodic alumina photonic crystals

“…to selectively transmit or reflect light of specific wavelengths or wavelength ranges -is a critical functionality for a broad range of optoelectronic and photonic devices and applications such as telecommunications, spectroscopy, imaging, lasers, diagnosis and medical therapies. [1][2][3] Optical filters can provide a precise control over electromagnetic waves by allowing and/or forbidding the pass of photons of certain energy/wavelength, enabling the fine control of light for specific applications. 4,5 Generally, optical filters are based on glass or plastic matrices, the optical properties of which are engineered by additional inorganic or organic coatings that enable the control and tuneability of the filtering features of the filter (e.g.…”

Phase Matching of Noncollinear Sum and Difference Frequency High Harmonic Generation

“…Due to the angular separation between the driving laser beams, phase-matching in noncollinear HHG [41,43] is fundamentally different from either single-beam HHG or collinear HHG [3,24,[44][45][46][47] and presents both new challenges and new opportunities. Previous investigations of noncollinear HHG have shown that phase matching effects can determine the angle of preferential harmonic emission and used this angular dependence to infer the difference in the magnitude of the harmonic and driving laser wavevectors [43].…”