Telluride colloidal quantum dots for telecommunication optical amplifiers

Several colloidally grown quantum dot systems have been demonstrated that show quantum confinement effects such as nanocrystallite size dependant absorption and fluorescence spectra. Bulk fluorescence spectra are blue shifted as the particle size is decreased and exciton-like features may be more apparent in the absorption and fluorescence spectra of individual dots or narrow size distributions of dots. The upper fluorescence wavelength limit is determined by the emission wavelength of the bulk material. For telecommunications applications at 1300 nm and 1550 nm the most popular colloidal systems, CdSe and CdS are therefore not appropriate. The paper shows our latest results with HgTe colloidal quantum dots where the fluorescence extends from around 1 /spl mu/m to almost 2 /spl mu/m, and with quantum efficiencies as high as 40% when pumped in the visible with an Argon ion laser running on all-lines. We have found that 3D quantum confinement effects in nanocrystallites may be used to size-tune the absorption and fluorescence so that the latter can be positioned to cover the 1300 nm and 1550 nm telecommunications windows.