Data capacity analysis of spectrally encoded quantum dots

A group of quantum dots (QDs) can be designed to have a unique spectral emission by varying the size of the QDs (wavelength) and number of QDs (intensity). This technique has been previously proposed for fluorescent tags and object identification. The potential of this system lies in the ability to have a large number of distinguishable wavelengths and intensity levels and therefore a large number of unique spectral codes. In this work, we model the spectral overlap between QD colours and the variations in intensity values and propose communication systems algorithms, such as minimum mean square error equalization and maximum likelihood sequence detector, that overcome both of these limiting factors. Through simulations we demonstrate these algorithms being effective at reading QD spectral codes with 6 intensity levels and 6 colours resulting in 46,655 spectral codes.