High harmonic generation

About: High harmonic generation is a research topic. Over the lifetime, 11694 publications have been published within this topic receiving 222650 citations. The topic is also known as: HHG.

A 0.92-THz SiGe Power Radiator Based on a Nonlinear Theory for Harmonic Generation

Abstract: We propose a nonlinear device model and a systematic methodology to generate maximum power at any desired harmonic. The proposed power optimization technique is based on the Volterra-Wiener theory of nonlinear systems. By manipulating the device nonlinearity and optimizing the embedding network, optimum conditions for harmonic power generation are provided. Using this theory, a 920–944-GHz frequency quadrupler is designed in a 130-nm SiGe:C process. The circuit achieves the peak output power of −17.3 and −10 dBm of effective isotropic radiated power and consumes 5.7 mW of dc power. To the best of our knowledge, this circuit demonstrates the highest generated power among Si/SiGe-based sources at this frequency range.

Atoms in high intensity mid-infrared pulses

Abstract: The recent development of intense, ultrashort, table top lasers in the mid-infrared opens new avenues for research in strong field atomic physics. Electrons submitted to such radiation acquire huge quiver energies, even at moderate intensity and interesting properties arise: first, the wavelength offers a convenient experimental knob to tune the ionisation regime by controlling the Keldysh parameter. Second, many processes like above-threshold ionisation or high harmonic generation, whose characteristics depend directly on this energy, can be pushed to unprecedented limits. Third, the wavelength controls the spectral phase of the harmonics and hence the possibility to improve the generation of pulses in the attosecond regime. Recent studies of rare gas and alkali atoms' photoelectron spectra and harmonic generation at 2 and 3.6 μm have begun to confirm the theoretical predictions. However, unexpected features have also been found showing that strong field interaction still keeps some secrets after more th...

Echo-enabled harmonics up to the 75th order from precisely tailored electron beams

Abstract: Echo-enabled harmonic generation has been used to seed a free-electron laser and has been demonstrated up to the 75th harmonic, producing 32 nm light from a 2,400 nm laser.

Extreme ultraviolet vector beams driven by infrared lasers

Abstract: Vector beams, beams with a non-uniform state of polarization, have become an indispensable tool in many areas of science and technology. Harnessing topological light properties paves the way to control and manipulate light–matter interactions at different levels, from the quantum to macroscopic physics. Here we generate tabletop extreme ultraviolet (EUV) vector beams driven by high-order harmonic generation (HHG). Our experimental and theoretical results demonstrate that HHG imprints the polarization state of the fundamental (infrared) beam, ranging from radial to azimuthal, into the higher frequency radiation. Our numerical simulations also demonstrate that the generated high-order harmonic beams can be synthesized into attosecond vector beams in the EUV/soft x-ray regime. Our proposal overcomes the state-of-the-art-limitations for the generation of vector beams far from the visible domain and could be applied in fields such as diffractive imaging, EUV lithography, or ultrafast control of magnetic properties.

Nonlinear Effects in Surface Acoustic Waves

Abstract: Experimental results on harmonic generation and parametric mixing of surface acoustic waves are reported. Harmonics of signals at 615 MHz and 1.69 GHz propagating on YZ LiNbO3 substrates were observed: the experiments on parametric mixing used two surface acoustic waves at f1=490 MHz and f2=1.09 GHz. Optical probing technique was used to observe directly the spatial variations of the harmonics, the sum, and difference frequency signals. It will be shown that the nonlinear interactions can be phenomenologically described by coupled amplitude equations. The nonlinear coupling constants are determined by comparing the experimental results with the calculations.