|Construction- Optical Fibres consists of thousands of extremely thin and long strands of high-quality glass/quartz. A strand may have a diameter of nearly 1 micrometer (10-6 m). The optical fibres are coated with a thin layer of material of lower refractive index.|
The refractive index of the main fibre is nearly 1.7. The refractive index of coating is nearly 1.5.