Evanescent field amplification in a tapered single-mode optical fibre

Abstract

We describe the fabrication and characterisation of an optical amplifier based on a tapered single-mode optical fibre immersed in a circulating dye solution. Optical gains of over 20 dB have been measured for pump powers of less than one watt, while the onset of gain saturation has been observed for pump powers of only tens of milliwatts.