Abstract

Characterization and modeling of Er-doped fibres [1] allowed in the past years fruitful developments of amplifiers and lasers. Since in a conventional fibre monomodal propagation of light is achieved in a very short length (once energy of other modes has been radiated) the cutback technique has been successfully used to determine absorption cross sections at the pump and gain band wavelengths. Emission cross sections have been usually determined instead from the measurement of gain or amplified spontaneous emission (ASE) spectrum together with the use of theoretical models. In a photonic crystal fibre (PCF) the limited size of the air-holes lattice originates energy radiation from the highest order confined mode [2]. Therefore, in order to avoid radiation from the fundamental mode, a bimodal structure with an effective monomodal behavior is sometimes preferred. In this case monomodal propagation is not achieved in a short length and the use of the cutback technique to determine absorption cross sections is prevented. On the other hand fusion splicing of PCFs to other components made of conventional fibres originates non negligible losses [3] that cannot be easily measured.

© 2009 IEEE