dc.contributor |
Universitat de Barcelona |
dc.contributor.author |
Garrido Fernández, Blas |
dc.contributor.author |
García Favrot, Cristina |
dc.contributor.author |
Seo, S.-Y. |
dc.contributor.author |
Pellegrino, Paolo |
dc.contributor.author |
Navarro Urrios, Daniel |
dc.contributor.author |
Daldosso, Nicola |
dc.contributor.author |
Pavesi, Lorenzo |
dc.contributor.author |
Gourbilleau, Fabrice |
dc.contributor.author |
Rizk, Richard |
dc.date |
2009-12-29T10:57:58Z |
dc.date |
2009-12-29T10:57:58Z |
dc.date |
2007 |
dc.identifier.citation |
0163-1829 |
dc.identifier.citation |
564621 |
dc.identifier.uri |
http://hdl.handle.net/2445/10634 |
dc.format |
15 p. |
dc.format |
application/pdf |
dc.language.iso |
eng |
dc.publisher |
The American Physical Society |
dc.relation |
Reproducció digital del document publicat en format paper, proporcionada per PROLA i http://dx.doi.org/10.1103/PhysRevB.76.245308 |
dc.relation |
Physical Review B, 2007, vol. 76, núm. 24, p. 245308-1-245308-15 |
dc.relation |
http://dx.doi.org/10.1103/PhysRevB.76.245308 |
dc.rights |
(c) The American Physical Society, 2007 |
dc.rights |
info:eu-repo/semantics/openAccess |
dc.subject |
Materials nanoestructurats |
dc.subject |
Propietats òptiques |
dc.subject |
Matèria condensada |
dc.subject |
Condensed matter |
dc.subject |
Electronic structure of bulk materials |
dc.subject |
Optical properties |
dc.title |
Excitable Er fraction and quenching phenomena in Er-doped SiO2 layers containing Si nanoclusters |
dc.type |
info:eu-repo/semantics/article |
dc.type |
info:eu-repo/semantics/publishedVersion |
dc.description.abstract |
This paper investigates the interaction between Si nanoclusters Si-nc and Er in SiO2, reports on the optical
characterization and modeling of this system, and attempts to clarify its effectiveness as a gain material for
optical waveguide amplifiers at 1.54 m. Silicon-rich silicon oxide layers with an Er content of 4–6
1020 at./cm3 were deposited by reactive magnetron sputtering. The films with Si excess of 6–7 at. %, and
postannealed at 900 °C showed the best Er3+ photoluminescence PL intensity and lifetime, and were used for
the study. The annealing duration was varied up to 60 min to engineer the size and density of Si-nc and
optimize Si-nc and Er coupling. PL investigations under resonant 488 nm and nonresonant 476 nm pumping
show that an Er effective excitation cross section is similar to that of Si-nc 10−17–10−16 cm2 at low
pumping flux 1016–1017 cm−2 s−1, while it drops at high flux 1018 cm−2 s−1. We found a maximum
fraction of excited Er of about 2% of the total Er content. This is far from the 50% needed for optical
transparency and achievement of population inversion and gain. Detrimental phenomena that cause depletion
of Er inversion, such as cooperative up conversion, excited-stated absorption, and Auger deexcitations are
modeled, and their impact in lowering the amount of excitable Er is found to be relatively small. Instead,
Auger-type short-range energy transfer from Si-nc to Er is found, with a characteristic interaction length of
0.4 nm. Based on such results, numerical and analytical Er as a quasi-two-level system coupled rate equations
have been developed to determine the optimum conditions for Er inversion. The modeling predicts that
interaction is quenched for high photon flux and that only a small fraction of Er 0.2–2 % is excitable through
Si-nc. Hence, the low density of sensitizers Si-nc and the short range of the interaction are the explanation of
the low fraction of Er coupled. Efficient ways to improve Er-doped Si-nc thin films for the realization of
practical optical amplifiers are also discussed. |