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

Abstract : 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.