Superfluorescence from Yb- and Yb–Er-doped phosphotellurite glass fibres

Short length, air-clad, multimode fibres were fabricated using high concentration Yb- and Yb–Er-doped phosphotellurite glass. Superfluorescent light sources are obtained by optically pumping the fibres using a 980 nm laser diode. Ytterbium-doped fibre showed amplified spontaneous emission (ASE) in the 1000–1100 nm wavelength region, whereas Yb–Er-codoped fibre in both 1000–1100 nm (due to Yb3+ ions) and 1450–1650 nm (due to Er3+ ions) wavelength regions. The ASE spectra from the fibres are compared for different fibre lengths and pump powers. The observed change in the ASE spectral shape and the shift in peak wavelength with the length of the optical fibre is discussed.