Optical properties of integrated waveguides incorporating semiconducting single-wall carbon nanotubes
Résumé
Carbon nanotubes (CNT) exhibit outstanding optical, electrical and mechanical properties. Thanks to advances in material quality and separation methods, an increased attention has been drawn to the implementation of CNT-based photonic devices compatible with silicon technology. Light-emitting devices based on electro- and photo-luminescent properties of semiconducting single-wall carbon nanotubes (s-SWCNT) have been implemented. However, none of these results were demonstrated in the telecommunications-relevant range around 1.55 µm.
Enrichment in s-SWCNTs with emission wavelengths tunable to the dominant telecommunications spectral window is achieved by controlling the parameters of SWCNT synthesis and dispersion in polyfluorene-based polymers. Organic films containing selected chiralities of s-SWCNT are spin-coated onto Si substrates and optically characterized (refractive index, absorption and photoluminescence).
Ridge waveguides are then fabricated using processing steps compatible with CMOS technology and exhibit single-mode propagation at 1.55 µm. Using these waveguides, guided photoluminescence (PL) from s-SWCNT is demonstrated for the first time around 1.55 µm. Alternatively to previous approaches, s-SWCNT are incorporated in the core layer of the waveguiding structure to benefit from an increased coupling efficiency of s-SWCNT PL with the waveguide optical mode. These findings underscore the utility of s-SWCNT for the development of silicon photonics around 1.55 µm.