Pustaka Ilmiah Universitas Padjadjaran

Abstrak

Photonic Jet To Improve The Lateral Resolution Of Laser Etching

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 um. 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 um and despite the low absorption, micrometric etchings have also been achieved on glass using larger microspheres.