RAMAN SCATTERING AND GAIN IN SILICON-ON-INSULATOR NANOWIRE WAVEGUIDES

Abstract

Raman scattering in air-covered and SiO2 -covered Silicon-on-insulator waveguides of 1.25 cm length, 220 nm height and two widths of 2 μm or 0.45 μm was investigated. A continuous wave (CW) Raman fiber laser at 1454.8 nm with linewidth of <0.1 nm was used as a pump source. The coupling efficiency was estimated to be around 10% for one end facet. Spontaneous Raman shift of 521 cm-1 (1574.2 THz) scattering was observed at 1573.8 nm for SOI waveguides in air and 1574.2 nm for waveguides covered with SiO2 at pump power of <1.5 mW inside both waveguides of 2 and 0.45 μm. Anti-Stokes scattering was observed at 1352.8 nm with pump power of 16 mW. The stimulated Raman gain was calculated from spontaneous Raman efficiency. Total Raman on-off gain was determined to be 0.6 dB for waveguide with width of 2 μm and 1 dB for waveguide with width of 0.45 μm.