Assessment of the main material issues for achieving an Er coupled to silicon nanoclusters infrared amplifier

In this work we present the state of the art of our work to obtain an infrared optical amplifier in which Er3+ doped SiO2 sensitised with Si nanoclusters (Si-nc) act as the active material to provide the signal amplification. As a result of a careful optimisation of the deposition parameters we have achieved that the Er3+ fraction coupled with the Si-nc with respect to the total optically active Er3+ content is about 23%. This result has been determined both by quantitative measurements of the first excited state population and by pump and probe amplification measurements under non-resonant pumping, where 1 dB cm(-1) of internal gain (reduction of 2 dB cm(-1) of the initial absorption losses) has been obtained. We will discuss several material issues that are mandatory to address and then overcome in order to optimise the fraction of Er3+ coupled to Si-nc, with the aim of exciting all the ions through indirect transfer. In particular we will address: carrier absorption (CA) in Si-nc, cooperative up-conversion and non-radiative recombination in Er3+, together with the distance dependent interaction and Auger back-transfer processes in the Er/Si-nc coupled system. (C) 2008 Elsevier B.V. All rights reserved.