Femtosecond Laser-Micromachining of Glass Micro-Chip for High Order Harmonic Generation in Gases

Abstract

We report on the application of femtosecond laser micromachining to the fabrication of complex glass microdevices, for high-order harmonic generation in gas. The three-dimensional capabilities and extreme flexibility of femtosecond laser micromachining allow us to achieve accurate control of gas density inside the micrometer interaction channel. This device gives a considerable increase in harmonics’ generation efficiency if compared with traditional harmonic generation in gas jets. We propose different chip geometries that allow the control of the gas density and driving field intensity inside the interaction channel to achieve quasi phase-matching conditions in the harmonic generation process. We believe that these glass micro-devices will pave the way to future downscaling of high-order harmonic generation beamlines.

Optical Waveform Synthesis and Its Applications

“…[25,121,146,[149][150][151] ii) The optimization of the macroscopic conditions (phase-matching). [112,[152][153][154][155][156][157][158] iii) The increase of the HHG single-atom conversion efficiency by sculpting the driving waveform with sub-cycle precision. [5,6,[159][160][161][162] The latter approach can be implemented in the time-domain by coherently combining different electric fields, that is, via WS technology, or in the frequency-domain by shaping the phase of different spectral components via spectral phase modulators.…”

Time-Resolved Imaging of Femtosecond Laser-Induced Plasma Expansion in a Nitrogen Microjet

“…The nozzle has been designed for application to high-order harmonic generation (HHG) [6] and ultrafast spectroscopy. In particular, it has been thought of as a component of a more complex microfluidic FLICE device aiming at achieving gas density manipulation on the micron-scale for efficient high-order harmonic generation on a chip [7]. In this work, we studied the hydrodynamic expansion of a nitrogen micro-jet in the wavefield of intense femtosecond laser pulses.…”

Femtosecond laser micromachining of integrated glass devices for high‐order harmonic generation

“…Indeed, there are examples in the literature of microfluidic chips dedicated to gas sensing 10 . Moreover, these empty structures buried inside glass can also be used as hollow waveguides that are particularly useful for high‐field laser applications like spectral broadening, pulse compression, and high‐order harmonic generation (HHG) 11–13 …”

“…10 Moreover, these empty structures buried inside glass can also be used as hollow waveguides that are particularly useful for high-field laser applications like spectral broadening, pulse compression, and high-order harmonic generation (HHG). [11][12][13] When a strong laser field interacts with a neutral gas, highly nonlinear optical processes occur, among which the generation of high-order harmonics of the driving field. This process is associated with the up-conversion of the fundamental laser frequency in a broad spectrum of radiation, extending from the extreme ultraviolet (XUV) up to the soft-X ray spectral domain.…”