There are indications that silicon nanocrystals (nc-Si) exhibit an optical gain that is potentially large enough to enable optical amplification in the wavelength range where intense photoluminescence (PL) is measured (600-1000 nm).  We fabricated optical cavities on fused silica pieces ion-implanted with Si in order to form a nc-Si layer with a thicknes of about 1 µm. Si was implanted at four energies between 1 MeV and 1.9 MeV to an excess atomic concentration varying between 25% and 30%. The pieces were sandwiched between dielectric mirrors consisting of multilayer interference filters. Over a wavelength range of about 200 nm wide, one filter reflects nearly 100%, while the other one shows an average reflection of 90%. We measured and compared the PL spectra of three samples: the first one with no mirrors, the second one with filters reflecting around 765 nm, and the third one with filters acting around 875 nm.  PL as a function of optical pumping power showed no increase characteristic of stimulated emission.  Comparison of the luminescence from the different samples showed that the PL signal is lowered in the wavelength domain where the filters act, an effect that seems to show that there is no net amplification of the signal in the cavity at pump laser intensities considered (~500 mW/cm²).

Alexandre Bibeau-Delisle*, Département de physique et RQMP, Université de Montréal, Canada
F. Schiettekatte, Département de physique et RQMP, Université de Montréal, Canada
B. Baloukas, Département de génie physique et RQMP, École polytechnique de Montréal, 
L. Martinu, Département de génie physique et RQMP, École polytechnique de Montréal, Canada
D. Barba, INRS-Énergie, Matériaux et Télécommunications, Varennes, Québec, Canada
F. Martin, INRS-Énergie, Matériaux et Télécommunications, Varennes, Québec, Canada
G. G. Ross, INRS-Énergie, Matériaux et Télécommunications, Varennes, Québec, Canada

*presenting author