Use of a YAG : Er laser with a chalcogenide fibre waveguide in laser surgery

Abstract

The damage thresholds of bulk high-purity chalcogenide glass samples and of fibre waveguides made from them were determined for YAG : Er laser radiation (λ = 2.94 μm). A cumulative effect was observed: the optical strength decreased during repetitive application of laser pulses and this was true both of the bulk samples and of the fibre waveguides. A correlation between the damage threshold and the concentration of heterophase inclusions was established experimentally. When the inclusion concentration was less than 104 cm-3, the damage threshold exceeded 1 kJ cm-2 for single pulses and was approximately half that in the pulse-periodic regime. The measured energy density of the λ = 2.94 μm radiation, needed for efficient cutting of the crystalline lens biotissues in the human eye, amounted to 50 J cm-2. The feasibility of constructing a scalpel with an Er laser and transmission of its high-power radiation (up to 1 kJ cm-2) along a chalcogenide fibre waveguide was demonstrated in principle.