Towards high-power mid-IR light source tunable from 3.8 to 4.5 µm by HBr-filled hollow-core silica fibres

Fibre lasers operating at the mid-IR have attracted enormous interest due to the plethora of applications in defence, security, medicine, and so on. However, no continuous-wave (CW) fibre lasers beyond 4 μm based on rare-earth-doped fibres have been demonstrated thus far. Here, we report efficient mid-IR laser emission from HBr-filled silica hollow-core fibres (HCFs) for the first time. By pumping with a self-developed thulium-doped fibre amplifier seeded by several diode lasers over the range of 1940–1983 nm, narrow linewidth mid-IR emission from 3810 to 4496 nm has been achieved with a maximum laser power of about 500 mW and a slope efficiency of approximately 18%. To the best of our knowledge, the wavelength of 4496 nm with strong absorption in silica-based fibres is the longest emission wavelength from a CW fibre laser, and the span of 686 nm is also the largest tuning range achieved to date for any CW fibre laser. By further reducing the HCF transmission loss, increasing the pump power, improving the coupling efficiency, and optimizing the fibre length together with the pressure, the laser efficiency and output power are expected to increase significantly. This work opens new opportunities for broadly tunable high-power mid-IR fibre lasers, especially beyond 4 μm.

A Review on Physical and Optical Properties of Zinc Tellurite Glasses Co-doped with different rare earth ions

In this work we review the effect of physical and optical properties with different ion zinc contents of tellurite base glass. The physical properties of the glasses were evaluated and the change in density, molar volume and ionic packing density in these glasses indicates the effect of ZnO different content show on the glasses structure. The study of optical properties such as the optical band gap and refractive index of zinc tellurite glass were studied. Zinc Tellurite glasses doped with Er3+ ions were synthesized by varies researcher. The glasses were characterized by X- ray diffraction, optical absorption and photoluminescence spectra. The glassy nature of zinc Tellurite host glass has been confirmed through XRD measurements. The glasses doped or co-doped with rare-earth ions have generated much interest due to the possibility of several promising applications such as optical data storage, visible laser, fibre amplifier, optical communication and sensor devices

Optical Communications: The Beginning

The first efforts by Alexander Graham Bell at optical communications by incoherent light are discussed. Those were very inefficient at the time but after the invention of the laser it was only a question of time when coherent optical communication will dominate the communications scene The beginning was slow because propagation both in air and in fibre waveguide was too large. Enormous efforts by the Corning Glass Works brought down the attenuation to a figure as low as a few dbs per kilometre making some further applications feasible. The next break-through was the invention of the fibre amplifier enabling the erection of long relay-free lines (maybe up to 10,000 km) possible range of applications was greatly extended by the invention of the fibre amplifier. Coherent light propagation in thin, single-mode fibres is discussed a very thin fibre is discussed. It is shown that an optical fibre can carry an enormous number of communication channels. The laser was invented just in time to help produce the signals, and it also became possible to produce pure enough glass fibres in which an optical signal could propagate with low attenuation. The invention of erbium-doped fibre amplifiers allowed them to be spread all over the world, including large number of lines under the oceans.