SUPPLEMENTARY INFORMATION PAPER Optical gain in silicon nanostructures P11118 AUTHORS Pavesi, Dal Negro, Mazzoleni, Franzo, Priolo 14000 12000 10000 -1 GAIN (cm ) 8000 6000 4000 2000 0 -2000 -4000 550 600 650 700 750 800 850 900 W avelength (nm) Figure 1. Wavelength dependence of the single pass gain values for the Si nanocrystals implanted into quartz. The figure shows only a few data points because of the limited number of wavelengths available to us. The other various experimental details are the same as those described in the manuscript. 120 80 -1 Gain (cm ) 40 0 -40 -80 -120 -160 fit to eq. (1-paper) with eq. (1-letter) -200 450 500 550 600 650 700 750 800 850 900 950 Wavelength (nm) . Figure 2: (full line) Spectral dependence of the net modal gain derived by using, 1 I g ln 2 L 1 (1) L IL where all the symbols have the same meanings as in Ref. [J. D. Thomson et al. Applied Physics Letters 75 (1999) 2527]. The points refer to the data shown in Fig. 3 of the paper obtained by fitting the ASE data. 2.0 SiO2/NS(n=1.89)/SiO2/air waveguide =0.097 SiO2/NS(n=1.71)/SiO2/air waveguide =0.017 1.8 1.4 1.2 1.0 0.8 refractive index Electric field (TE0) 1.6 0.6 0.4 0.2 0.0 -3.0 -2.0 -1.0 0.0 1.0 depth (m) Figure 3: Electric field profile for the fundamental TE mode of a four layers waveguide at a wavelength of 0.8 μm. The waveguide was formed by a 0.1 μm thick NS layer on top of a quartz substrate and capped by a 0.06 μm thick SiO2 layer. The external medium was air. The effective refractive index of the NS implanted region, for the full line plot, was M eff M f estimated by using the Maxwell Garnett approximation , which eff 2 M f 2 M is valid for spherical particles of dielectric constant (here we use =15.21 as for Si) embedded in a medium of dielectric constant M (here we use M =2.102 as for SiO2) with a volumetric fraction f=0.28 (corresponding to Si nanocrystals with a diameter of 3 nm and a density of 2x1019 cm-3) and yielded an effective dielectric constant eff =3.57. Then n eff =1.89. For the dotted line, we used an effective refractive index for the NS layer of 1.71 which was measured by ellipsometry on PE-CVD deposited NS. The profile of the refractive indexes of the two resulting structures is also shown. The optical filling factor of the mode is defined as .