High-order harmonic generation in a microfluidic glass device

Abstract

We report on the efficient generation of high-order harmonics in helium gas inside complex glass micro-devices fabricated by femtosecond laser micromachining. By exploiting the three-dimensional capabilities and extreme flexibility of this fabrication technique we developed fluidic micro-structures in a fused-silica substrate that allowed us to achieve accurate control of the gas density inside a micrometer-sized microchannel. As a result, we achieved a broadband spectrum of extreme ultraviolet (XUV) radiation which extends up to 200 eV and we observed a considerable increase in the harmonics generation efficiency if compared with traditional harmonic generation in gas jets. We foresee that the application of femosecond-laser-micromachined glass devices to high-order harmonics generation can be extended to more complex on-chip systems including different functionalities, thus opening the possibility to future miniaturization of XUV and Attosecond beamlines.

High-Fidelity Harmonic Generation in Optical Micro-Resonators Using BFGS Algorithm

“…The current literature of harmonic generation via nonlinear wave mixing is dominated by increasing the efficiency of the second/third harmonic generation rather than increasing the efficiency of an arbitrary harmonic . There are currently no known techniques in the literature that reported a high-efficiency in the microscale for an arbitrary harmonic generation (not necessarily the second harmonic) under monochromatic optical excitation [9][10][11][12][13][14][15][30][31][32][33][34][35][36][37][38][39]. In this study, we will show that for an arbitrary excitation frequency, one can maximize the harmonic generation efficiency at an arbitrary frequency.…”

“…A computational study that is based on maximizing the harmonic generation efficiency via a nonlinear programming algorithm is lacking [ 6 , 7 , 8 ]. Experimental studies usually focus on finding new techniques to increase the second and the third harmonic generation efficiency and there are relatively few experimental studies that have demonstrated a minor increase in the harmonic generation or conversion efficiency via certain experimental configurations and setups [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Some computational studies have focused on increasing the computation efficiency of harmonic generation problems rather than proving that the harmonic generation efficiency itself can actually be increased.…”

“…These include the studies mentioned in [ 6 , 7 , 8 ], which have managed to increase the efficiency of the nonlinear Finite-Difference-Time-Domain (FDTD) method by decreasing the dispersion error. The current literature of harmonic generation via nonlinear wave mixing is dominated by increasing the efficiency of the second/third harmonic generation rather than increasing the efficiency of an arbitrary harmonic [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. There are currently no known techniques in the literature that reported a high-efficiency in the microscale for an arbitrary harmonic generation (not necessarily the second harmonic) under monochromatic optical excitation [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 30 , 31 , 32 , 33 , …”

Modeling femtosecond pulse propagation and high harmonics generation in hollow core fibers

“…The integrated microfluidic glass device devoted to XUV generation by HHG in gas medium is composed [1] of a main micro-channel that works as a hollow-core waveguide (HCW) for the propagation of the femtosecond laser pulse. The interaction region is filled with the working gas using a micro-structured network of delivery channels fabricated in the same glass substrate.…”

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

“…Here we present a De Laval conical nozzle realized on a fused-silica slab through Femtosecond Laser Irradiation followed by Chemical Etching (FLICE). The nozzle has been designed for application to High-order Harmonic Generation (HHG) [6] and ultrafast spectroscopy. In particular, it has been thought as a component of a more complex microfluidic FLICE device aiming at achieving gas density manipulation on the micronscale for efficient high-order harmonic generation on a chip [7].…”