In this work, the morphological changes induced by laser irradiation on silicon are investigated. The effects are analyzed under vacuum and oxygen atmospheres. The excitation source is an Nd:YAG laser at 1064 nm. A novel method to cause silicon microstructuring on large areas is presented. The analysis is done by scanning electron microscopy. When the microstructuring is performed in an oxygen atmosphere, the damage consists of a semi-ordered array of conical structures. The first stages of growth show the importance of the crystallographic orientation of the initial surface. In vacuum, the growth is irregular and random. In both cases, the microstucturing results in cones (oxygen) or bumps (vacuum) that protrude above the initial surface.

We present a scheme, based on Bloch equations and Zeno-type measurements, that allows the control of the probability density evolution of the eigenstates of a V-type system. The equations are solved numerically and we present how the population in each level can be controlled using different sequences of “pulse measurements”. The entropy between the “measurement device” and the field used to perform the measurement process is evaluated for different strengths of such field, these calculations show that the entropy is maximized when we are in the Zeno regime. The results shown here unveil different possible strategies for controlling the population levels of a V-type system and could be implemented, for example, in trapped ions or RMN qubits.

We report the absorption/transmission properties of thin copper films slightly below the percolation limit produced by laser ablation; these samples show randomly positioned islands. Two types of films are grown: in the first type, copper is deposited on glass, and it is shown that as the amount of deposited copper approaches the percolation limit, the samples show enhanced light transmission; in the second set of samples, made of TiO$_2$/Cu/TiO$_2$ layers, the presence of titanium oxide inhibits light transmission enhancement, even though the same amount of copper has been deposited compared to the samples deposited on glass. We also present numerical calculations based on the discrete dipole method to simulate the optical behaviour of the copper films. The enhanced light transmission of the samples presented in this work resembles the Extraordinary Optical Transmission (EOT) observed in periodic metallic structures. The similarities and differences between experiment and numerical calculations and the possible use of these films as sensors are discussed.