Understanding light trapping by resonant coupling to guided modes and the importance of the mode profile

Fiona J. Beck; Alexandros Stavrinadis; Tania Lasanta; John Paul Szczepanick; Gerasimos Konstantatos

doi:10.1364/OE.24.000759

Understanding light trapping by resonant coupling to guided modes and the importance of the mode profile

Fiona J. Beck, Alexandros Stavrinadis, Tania Lasanta, John Paul Szczepanick, Gerasimos Konstantatos

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

We present a simple conceptual model describing the absorption enhancement provided by diffraction gratings due to resonant coupling to guided modes in a multi-layered structure. In doing so, we provide insight into why certain guided modes are more strongly excited than others and demonstrate that the spatial overlap of the mode profile with the grating is important. The model is verified by comparison to optical simulations and experimental measurements. We fabricate metal nanoparticle gratings integrated as back contacts in solution-processed PbS colloidal quantum dot photodiodes. The measured photocurrent at the target wavelength is enhanced by 250%, with reference to planar devices, due to resonant coupling to guided modes with strong spatial overlap with the gratings. In comparison, resonant coupling to weakly overlapping modes results in a 25% increase at the same wavelength.

Original language	English
Pages (from-to)	759-772
Number of pages	14
Journal	Optics Express
Volume	24
Issue number	2
DOIs	https://doi.org/10.1364/OE.24.000759
Publication status	Published - 25 Jan 2016

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abstract = "We present a simple conceptual model describing the absorption enhancement provided by diffraction gratings due to resonant coupling to guided modes in a multi-layered structure. In doing so, we provide insight into why certain guided modes are more strongly excited than others and demonstrate that the spatial overlap of the mode profile with the grating is important. The model is verified by comparison to optical simulations and experimental measurements. We fabricate metal nanoparticle gratings integrated as back contacts in solution-processed PbS colloidal quantum dot photodiodes. The measured photocurrent at the target wavelength is enhanced by 250%, with reference to planar devices, due to resonant coupling to guided modes with strong spatial overlap with the gratings. In comparison, resonant coupling to weakly overlapping modes results in a 25% increase at the same wavelength.",

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AU - Konstantatos, Gerasimos

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AB - We present a simple conceptual model describing the absorption enhancement provided by diffraction gratings due to resonant coupling to guided modes in a multi-layered structure. In doing so, we provide insight into why certain guided modes are more strongly excited than others and demonstrate that the spatial overlap of the mode profile with the grating is important. The model is verified by comparison to optical simulations and experimental measurements. We fabricate metal nanoparticle gratings integrated as back contacts in solution-processed PbS colloidal quantum dot photodiodes. The measured photocurrent at the target wavelength is enhanced by 250%, with reference to planar devices, due to resonant coupling to guided modes with strong spatial overlap with the gratings. In comparison, resonant coupling to weakly overlapping modes results in a 25% increase at the same wavelength.

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Understanding light trapping by resonant coupling to guided modes and the importance of the mode profile

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