Quantum Dots Luminescence Collection Enhancement and Nanoscopy by Dielectric Microspheres |
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Authors: | Francesco Biccari Travis Hamilton Andrea Ristori Stefano Sanguinetti Sergio Bietti Massimo Gurioli Hooman Mohseni |
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Institution: | 1. Department of Physics and Astronomy, University of Florence, Via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy;2. Bio-Inspired Sensors and Optoelectronics Laboratory, Northwestern University, 2145 Sheridan Rd, Evanston, IL, 60208 USA;3. Department of Physics and Astronomy, University of Florence, Via G. Sansone 1, I-50019 Sesto Fiorentino (FI), Italy
LENS - European Laboratory for Non-Linear Spectroscopy, University of Florence, Via N. Carrara 1, I-50019 Sesto Fiorentino (FI), Italy;4. Department of Material Science, University of Milano-Bicocca, Via Cozzi 55, I-20125 Milano, Italy |
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Abstract: | In recent years, dielectric microspheres have been used in conjunction with optical microscopes to beat the diffraction limit and to obtain superresolution imaging. The use of microspheres on quantum dots (QDs) is investigated, for the first time, to enhance the light coupling efficiency. The enhancement of the QD luminescence collection in terms of extraction and directionality is demonstrated, as well as the enhancement of spatial resolution. In particular, it is found that a dielectric microsphere, placed on top of an epitaxial QD, increases the collected radiant energy by about a factor of 42, when a low numerical aperture objective is used. Moreover, if two or more QDs are present below the microsphere, the modification of the far field emission pattern allows selective collection of the luminescence from a single QD by simply changing the collection angle. Dielectric microspheres present a simple and efficient tool to improve the QD spectroscopy, and potentially QD-based devices. |
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Keywords: | microspheres near field photoluminescence photonic nanojet |
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