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Significance Statement
The standard technique for micromachining making use of focused Gaussian beams determines a high degree of spatial energy confinement with an aspect ratio given by the focal volume, imposing a constraint on the speed and quality of the microfabrication in some applications (e.g., waveguide writing, deep-drilling or high-speed cutting) where larger dimensions of the machined structures are
required. In fact, nonconventional beam shapes are more and more under investigation and are designed to meet the requirements of a given material configuration or application that could not be feasible with Gaussian beams.
The work presented here illustrates the potentiality of stationary wave packets such as pulsed Bessel beams (with large non-diffracting lengths) for laser micromachining applications. In particular the work highlights the possibility to inscribe in single shot smooth high aspect-ratio microstructures in transparent dielectric materials.
Figure Legend
Transverse intensity profiles (first row) and 3D surface plot (second row) of high order Bessel beams (from left to right J0, J4, J8 and J12 Bessel beams) generated by means of a spatial light modulator and used for single shot laser micromachining applications.
Journal Reference
Applied Physics A, 2015, Volume 120, Issue 1, pp 385-391.
Ottavia Jedrkiewicz 1, Simone Bonanomi 2, Marco Selva 2, Paolo Di Trapani2
[expand title=”Show Affiliations”]- Istituto di Fotonica e Nanotecnologie, CNR and CNISM UdR Como, Via Valleggio 11, 22100, Como, Italy
- Dipartimento di Scienza e Alta Tecnologia, University of Insubria and CNISM UdR Como, Via Valleggio 11, 22100, Como, Italy
Abstract
We report on experiments on glass material modification using nondiffractive high-order picosecond pulsed Bessel beams, generated by a spatial light phase modulator and then suitably demagnified. We investigate the possibility to generate in single-shot tubular microstructures across 100-μm-thin borosilicate glass, when a suitable energy range is considered, and we highlight the effect of the unstable propagation regime for very high input energies, leading to a breakup of the tubular microstructure. The micromachined glass samples are observed on their top and bottom surfaces as well as longitudinally along their thickness. For the conical beam geometry used, we observe no internal material modification pattern with pulses in the femtosecond range. A comparison with glass machining by means of a focused ring-shaped beam is also presented. The results highlight the role of the conical energy flux for single-shot smooth high aspect ratio material modification in a regime where nonlinear Kerr effects are absent.
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