Stimulated emission in the active planar optical waveguide made of silicon nanocrystals

Thin layers of silicon nanocrystals prepared by silicon-ion implantation into silica substrate form active planar optical waveguides. Testing experiments of optical gain have been performed on a sample implanted to a dose of 4×1017 cm-2 by using the variable stripe length (VSL) technique. The photoluminescence collected from the sample facet shows spectrally narrow, polarization-resolved transverse electric (TE) and transverse magnetic (TM) substrate modes. Continuous wave VSL revealed a reduction of optical losses in both modes only. On the contrary, a fast decay component due to amplified spontaneous e-mission is observed in time-resolved VSL experiments. This fast component shows positive net modal optical gain of ∼12 cm -1. The observed superlinear emission as a function of pump intensity, accompanied by shortening of the fast component lifetime, supports further the observation of stimulated emission. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.