Optical, measuring, signaling and checking apparatus and instruments in the nature of optical light sources based on nonlinear optical media and optical telecommunications hardware, namely, optical filters for wavelength division multiplexing and optical switches; fibre optic components, namely, fibre Bragg gratings for optical processing; fibre lasers that act as optical sources in optical telecommunication systems; optical measuring, signalling and checking apparatus and instruments in the nature of optical light guides, namely, waveguides for high power optical beam delivery, fibre optics and optical fibre lasers not for medical purposes; optical fibre gratings in the form of a component based on a periodic variation of the refractive index in optical light guides used in optical telecommunications for equalisation of optical amplifiers and used in optical sensing as a sensor element; thermometers and pressure sensors, namely, optical fibre sensors used as for wavelength response to changes in temperature and strain; optical fibres cables and optical fibre components used in telecommunications and optical sensing, namely, fibre Bragg gratings, fibre-based wavelength division multiplexed (WDM) networks, fibre-coupled optical isolators and fibre attenuators