Silver halide IR fibre with extra small diameter

Abstract

We developed fine extrusion dies and accessories for implementing the direct high-temperature extrusion. It allowed us to fabricate a silver halide polycrystalline single-layer fibre of a new miniaturization level. This fibre has a diameter of 110 μm (the previous minimum diameter was 300 μm). We measured the fibre’s optical properties, such as refractive index dispersion, transmission range, optical losses including bending losses, mode field distribution of CO2 laser radiation at 10.6 μm (in the far field). We also estimated the roughness of the fibre lateral surface and the ellipticity of the fibre end faces. It was found that 110 μm fibre is highly transparent in the wavelength range of 2-20 μm and has low bending losses. It has rather smooth surface, the almost perfect circle cross-section and the small deviation of the nominal diameter along the fibre. These fibres, assembled in mechanical fibre bundles, may be useful for IR imaging, IR spectroscopy, and IR microscopy. They also may be used as billets of inserts for various PCFs and fibre bundles with common background cladding (matrix) with improved functional characteristics.