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Final Activity Report Summary - NOWAL (Nanocluster-sensitised optical waveguide amplifiers and lasers)

In this project, the viability of an erbium-doped laser or amplifier indirectly pumped through silicon nanoclusters has been studied. This optical pumping scheme would dramatically decrease the cost of these devices because the pump device would be subject to much less constraints, thus it would have an impact in the telecommunications industry. At the end of the project, the indirectly pumped laser or amplifier has not been demonstrated yet. However, the project has produced important contributions towards the understanding of the material, and towards ways to overcome some unexpected technical difficulties that have been encountered.

Regarding the material understanding, a model has been proposed for the energy transfer mechanism from the nanoclusters to the Er. A distant dependent model explains many experimental observations and also the difficulties to indirectly excite a high population fraction, providing some strategies that would lead to a more efficient excitation.

On the other hand, problems associated with the stress in the films during annealing have been investigated, and a solution consisting of annealing the layer after etching the ribs has been proposed and proved to be successful.

Finally, the ultimate issues preventing the observation of net gain in these waveguides have been identified. The main difficulties were found to be:
(i) the propagation loss, which was found to be around 3 dB/cm, which is comparable to the expected gain, making net gain difficult;
(ii) the difficulty of indirectly exciting a high ratio of Er population, due to the distance dependent interaction between nanoclusters and Er.

Reported by

University of Southampton
SO9 5NH Southampton
United Kingdom
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