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Published July 2, 2015 | public
Journal Article

A colloidal quantum dot spectrometer


Spectroscopy is carried out in almost every field of science, whenever light interacts with matter. Although sophisticated instruments with impressive performance characteristics are available, much effort continues to be invested in the development of miniaturized, cheap and easy-to-use systems. Current microspectrometer designs mostly use interference filters and interferometric optics that limit their photon efficiency, resolution and spectral range. Here we show that many of these limitations can be overcome by replacing interferometric optics with a two-dimensional absorptive filter array composed of colloidal quantum dots. Instead of measuring different bands of a spectrum individually after introducing temporal or spatial separations with gratings or interference-based narrowband filters, a colloidal quantum dot spectrometer measures a light spectrum based on the wavelength multiplexing principle: multiple spectral bands are encoded and detected simultaneously with one filter and one detector, respectively, with the array format allowing the process to be efficiently repeated many times using different filters with different encoding so that sufficient information is obtained to enable computational reconstruction of the target spectrum. We illustrate the performance of such a quantum dot microspectrometer, made from 195 different types of quantum dots with absorption features that cover a spectral range of 300 nanometres, by measuring shifts in spectral peak positions as small as one nanometre. Given this performance, demonstrable avenues for further improvement, the ease with which quantum dots can be processed and integrated, and their numerous finely tuneable bandgaps that cover a broad spectral range, we expect that quantum dot microspectrometers will be useful in applications where minimizing size, weight, cost and complexity of the spectrometer are critical.

Additional Information

© 2015 Macmillan Publishers Limited. Received 15 August 2013; Accepted 12 May 2015; Published online 01 July 2015. The inception, experiments and initial analysis in this work was funded by the ARO through the Institute for Soldier Nanotechnologies (W911NF-07-D-0004). During further analysis and modelling, J.B. was supported by Tsinghua University and the Division of Physics, Mathematics and Astronomy at the California Institute of Technology. Author Contributions: J.B. designed the experiments with contributions from M.G.B. J.B. performed the experiments. Both authors discussed the results. J.B. wrote the manuscript with contributions from M.G.B. Author Information Reprints and permissions

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