Transversely excited atmospheric pressure CO2 and modulated continuous-wave CO2 laser marking of soda-lime and borosilicate glasses has been investigated as a function of laser fluence and pulse duration. Marks are formed by a combination of surface crazing and material removal, the latter occurring predominantly through particles that are fractured from the surface. Various possible fracture mechanisms are analyzed and residual surface stress following rapid laser heating is identified as the most likely cause of microcracking. Scanning electron microscope studies show that relatively large fragments are produced, with a characteristic thickness that is dependent on the laser pulse duration, but that they predominantly remain locked in the surface. Gas phase products evolved during the interaction have also been subject to evaluation using spectroscopy of the luminous plume and fast photography techniques.

Sapphire (AlzO,) and silica samples have been implanted with 400 keV europium ions at fluences between 5X 1014 and 1 X 10"' ions cm-*. As-implanted, samples show luminescence at 622 nm, and although the intensity may be increased by furnace anneals up to 1000 "C, higher temperatures, to 1200 "C, result in less emission, as the impurity ions form precipitate clusters. This problem can be avoided by the use of pulsed laser anneals which dissociate the clusters and quench in atomically dispersed ions. The luminescence intensity has been increased by factors of 95 and 85 for sapphire and silica, respectively, relative to the initial implanted signal. On comparing with furnace anneals at 1200 'C, the pulsed laser annealing is more effective, by factors of up to 45 times. Data for pulsed excimer and CO2 lasers are compared. Both types of laser appear to remove the ion-implanted radiation damage, but in the case of silica, higher luminescence performance was obtained with the excimer anneals. There was no evidence for diffusion of the implanted em-opium, as assessed by Rutherford backscattering spectrometry. 0 I995 American Institute of Physics.

No abstract

Tin doped indium oxide (ITO) thin films provide excellent transparency and conductivity for electrodes in displays and photovoltaic systems. Current advances in producing printable ITO inks are reducing the volume of wasted indium during thin film patterning. However, their applicability to flexible electronics is hindered by the need for high temperature processing that results in damage to conventional polymer substrates. Here, we detail the conditions under which laser heating can be used as a replacement for oven and furnace treatments. Measurements of the optical properties of both the printed ITO film and the polymer substrate (polyethylene terephthalate, PET) identify that in the 1.5–2.0 μm wavelength band there is absorption in the ITO film but good transparency in PET. Hence, laser light that is not absorbed in the film does not go on to add a deleterious energy loading to the substrate. Localization of the energy deposition in the film is further enhanced by using ultrashort laser pulses (~1 ps) thus limiting heat flow during the interaction. Under these conditions, laser processing of the printed ITO films results in an improvement of the conductivity without damage to the PET.

Several applications of optical fibres for sensor and telecommunications require the polymer jacket to be stripped from the fibre, e.g. for the inscription of Bragg gratings. Here, we report an alternative approach to chemical and mechanical fibre jacket stripping based on laser ablation. It is shown that excellent quality removal is possible using the ultraviolet excimer and infra-red CO2 laser, provided the latter is tuned to a suitably strong absorption band in the polymer. Characterization of the ablation properties of the acrylic jacket material, and the optical and mechanical properties of the stripped fibre are reported.