Laser-induced diffraction patterns in germanium diselenide amorphous films.
We report the characterization of changes produced on germanium diselenide amorphous semiconductor thin films by a focused He-Ne laser beam. The diffraction pattern produced by the laser spot on the sample is studied as a function of the intensity and the irradiation time. At low intensities the state of polarization of the incident beam generates an asymmetry in the induced diffraction pattern. Moreover, if the polarization of the incident beam is rotated, the corresponding asymmetry rotates as well. These results show the difference between thermal and electromagnetic effects on the material. This system may be used as a high density recording medium.
Light-induced light absorption changes in AsSe and GeSe2 thin films
Abstract Reversible transmittance ( T ) changes for λ = 6328 A light were observed in stabilized AsSe and GeSe 2 thin films when irradiated by λ = 5145 A and λ = 4880 A wavelength exciting light pulses. During photodarkening, T reaches a steady state value obeying a T ∝ t -1 relationship then approaches its starting value exponentially when the light is switched off. Both of these processes develop in a few seconds. The transmittance changes are explained by variations in the absorption coefficients with temperature, controlled by the absorption and loss of energy.
Periodic surface ripples in laser‐treated aluminum and their use to determine absorbed power
We report the first observation of surface ripples produced on a metal (pure and implanted A1) during pulsed laser treatment (Nd:glass laser in TEM00 mode, λ = 1.06 μm, 7 ns FWHM). Fringes with a characteristic spacing equal to the incident wavelength are readily seen near the periphery of laser spot, over a narrow region, resulting in an accurate delineation of melt threshold. Comparison with the calculated melt threshold leads to determination of the absorbed power. This method to evaluate the absorbed power can be applied to any material exhibiting surface ripples characteristic of melt threshold.