Laser micromachining of transparent glass using ultrafast Bessel beams

Abstract

We fabricated optical waveguides in fused silica by focusing femtosecond laser pulses with an axicon. With this technique, we also produced microholes by using chemical etching. The axicon, which is a conical lens, generates an optical beam with a transverse intensity profile that follows a zero-order Bessel function. Bessel beams produced by axicon focusing have a narrow focal line of a few micron width which is invariant along a long distance (>1 cm). By focusing femtosecond pulses with an axicon into fused silica, we induced permanent modifications over the extented focal line of the axicon without scanning axially the glass sample. The waveguides so fabricated exhibit low losses and no detectable birefringence due their excellent circular symmetry. By translating the glass sample during the inscription process, we have fabricated planar waveguides. Microfluidic channels were obtained by soaking the exposed samples into a HF solution.

Spatio‐temporal dynamics in nondiffractive Bessel ultrafast laser nanoscale volume structuring

“…In this respect, reducing the dimensionality by the choice of non‐diffractive features presents certain advantages. Recently nondiffractive Bessel‐Gauss beams were demonstrated to show potential for a range of laser machining applications, from deep‐drilling, waveguide writing, efficient photoinscription of Bragg gratings, to large‐area processing and high‐aspect‐ratio volume nanostructuring . A particular attention is conveyed to the nonlinear interaction of non‐standard highly localized wavepackets including non‐diffractive zero‐order, higher order vortex Bessel beams, light bullets, or self‐accelerating beams .…”

High-resolution material structuring using ultrafast laser non-diffractive beams

“…Extrapolated to optical domains, this is specifically important in applications requiring the definition of sharp optical resonances and sub-wavelength sampling of optical signals in embedded optical systems. If Bessel laser photoinscription of integrated optical elements was demonstrated in the form of waveguides [35] or gratings [56,69], hybrid systems combining micro and nanosized features offer extended opportunities not only for transporting and routing the optical fields but also for sampling the optical signals, accessing thus the information within. This function can be achieved with periodic nanoscale modulation of the refractive index inside an optical waveguide determining a highly efficient Bragg optical resonance [70] or by inserting nanoscale non-perturbative scattering centers that can sample the field, read it, and reconstruct the spectral information [71,72].…”

“…Recently, a new class of optical beams emerged for processing applications [34][35][36][37][38][39][40] in hard and soft matter; the non-diffractive beams, and, within this class, notably the zero-order Bessel-Gauss beams (called hereafter Bessel beams for simplicity) [41][42][43][44][45]. These beams exhibiting a central spot resistant to diffraction reflect a particular longitudinal geometry of quasi-constant intensity and with a transverse profile given by a Bessel function J 0 .…”

From Localized Laser Energy Absorption to Absorption Delocalization at Volumetric Glass Modification with Gaussian and Doughnut-Shaped Pulses

“…The conventional way to perform volumetric laser processing is the use of Gaussian pulses. However, the spatially and/or temporally shaped pulses can be highly advantageous for many applications [20][21][22][23][24]. For example, Bessel laser beams have been shown to be much more efficient for high aspect ratio structuring of glass, as well as for drilling and cutting dielectric materials, compared to conventional Gaussian pulses [22,[25][26][27].…”

“…However, the spatially and/or temporally shaped pulses can be highly advantageous for many applications [20][21][22][23][24]. For example, Bessel laser beams have been shown to be much more efficient for high aspect ratio structuring of glass, as well as for drilling and cutting dielectric materials, compared to conventional Gaussian pulses [22,[25][26][27]. Further, top-hat laser pulses can be advantageous for uniform surface processing [28,29].…”