The techniques applying laser beams or optical systems are limited by the diffraction limit of the optical heads
used. We demonstrate theoretically and experimentally that the use of the photonic jet allows an improvement in
the optical resolution to achieve smaller etching without reducing the wavelength of the source. The potential of
the photonic jet using a nanosecond pulsed near-infrared laser for micro-fabrication is also demonstrated. These
lasers are the most common type of laser used in industrial processes because of their price and the fact that
well-packaged sources are available. Their typical spatial resolution in laser etching is limited by the spot size of
their focus point at around 25-70 μm. This is the reason why a photonic jet, a high spatial concentration onto a
half-wavelength spot of a beam that emerges in the vicinity of a dielectric microsphere, is of great interest. In our
experiments, micro-scale glass (ns = 1.5) and BaTiO3 spheres (ns = 1.9) have been used to achieve photonic jets. The etching process has been tested on two substrates: silicon wafers, which have a significant absorption at
1064 nm, and glass plates, which have a lower absorption at this wavelength. The smallest marking achieved on
silicon has an average diameter of 1.3 μm and despite the low absorption, micrometric etchings have also been
achieved on glass using larger microspheres.
An increase of industrial needs for micro-ablation and surface structuration using sub-picosecond laser working at high
repetition rate is required. In this context, new industrial lasers were recently commercialized for such a type of purpose.
The potential of a new industrial femtosecond laser source (Tangerine model from Amplitude Système) is investigated in
this work for different etching purposes. Our experimental results will be also compared to those obtained when using
Ti:Sa laser source, with the help of numerical simulations.
Laser processing applied to thin film silicon is an interesting approach for solar cell fabrication. In this work, we
investigate the effects of a continuous wavelength (CW) laser irradiation in solid phase or liquid phase of silicon on the structural and electrical properties of thin film silicon layers. Thus, results on CW laser induced crystallisation (LIC) of ultrathin amorphous silicon, laser induced epitaxy (LIE) of a thick amorphous silicon on a seed silicon layer, and laser induced thermal annealing (LIA) of polycrystalline silicon films are presented and discussed.