Comparison of the Optical Waveguide Behaviors of Se-Doped and Undoped CdS Nanoribbons by Using Near-Field Optical Microscopy

We report the Se-doped and undoped CdS nanoribbons synthesized by a Au-catalyzed thermal evaporation route, have good optical waveguide behaviors. Optical measurements demonstrate light can be guided on sub-wavelength scales along CdS nanoribbons with assembled structures, such as branched and crossed structures. The guided photoluminescence (PL) spectra along Se-doped and undoped CdS nanoribbons at different propagation distance were investigated by using near-field optical microscopy. Both the guided PL spectra of Se-doped and undoped CdS nanoribbons show redshifts because of the band-edge absorption. And the redshift of guided PL spectra of Se-doped nanoribbon is more than undoped CdS nanoribbon at the same PL propagation distance, because the internal disorder of Se-doped nanoribbon is more than that of undoped nanoribbon.