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Proceedings Paper

Detecting single photon signals with mirror-enhanced grating couplers (Conference Presentation)
Author(s): Anna P. Ovvyan; Pietro E. Lombardi ; Sofia Pazzagli ; Giacomo Mazzamuto; Günter Kewes ; Oliver Neitzke; Nico Gruhler; Oliver Benson; Wolfram H. P. Pernice; Francesco S. Cataliotti; Costanza Toninelli

Paper Abstract

We employ mirror enhanced grating couplers as convenient output ports for ridge Si3N4 waveguide to detect single photons emitted from Dibenzoterrylene (DBT) molecules coupled into propagating modes at room temperature. The coupling ports are designed for waveguide structures on transparent silica substrates for light extraction from the chip backside. Thus the coupling ports enable contact free readout of the waveguide devices by imaging through the silica substrate. Optimized grating structures provide maximum out-coupling efficiency at 785nm (the central emission wavelength of DBT) with a bandwidth of 50 nm and fulfill mode-matching to a Gaussian mode in free space (FWHM ≈ 4μm). Covering fully etched grating devices with a Hydrogen silsesquioxane buffer layer and a gold mirror increase the coupling efficiency compared to bare grating structures. The maximum single coupler efficiency predicted by finite element simulations is 90% which reduces to 60% when adapted to fabrication constrains, whereas the average measured coupling efficiency is 35±5%. We employ such grating ports to read out optical waveguides designed for single-mode operation at λ=785 nm. DBT molecules are coupled evanescently to the waveguides and transport emitted single photon signals to the coupling region upon optical pumping. Using a Hanbury Brown and Twiss setup we observe pronounced antibunching with g(2)(0)=0.50±0.05 from the grating couplers by excitation (λ=767nm) of a single DBT molecule which confirms the quantum nature of the outcoupled fluorescent light.

Paper Details

Date Published: 23 May 2018
Proc. SPIE 10683, Fiber Lasers and Glass Photonics: Materials through Applications, 106831C (23 May 2018); doi: 10.1117/12.2314472
Show Author Affiliations
Anna P. Ovvyan, Westfälische Wilhelms-Univ. Münster (Germany)
Pietro E. Lombardi , Univ. degli Studi di Firenze (Italy)
Sofia Pazzagli , Istituto Nazionale di Ottica (Italy)
Giacomo Mazzamuto, LENS - Lab. Europeo di Spettroscopie Non-Lineari (Italy)
Günter Kewes , Humboldt-Univ. zu Berlin (Germany)
Oliver Neitzke, Humboldt-Univ. zu Berlin (Germany)
Nico Gruhler, Westfälische Wilhelms-Univ. Münster (Germany)
Oliver Benson, Humboldt-Univ. zu Berlin (Germany)
Wolfram H. P. Pernice, Westfälische Wilhelms-Univ. Münster (Germany)
Francesco S. Cataliotti, LENS - Lab. Europeo di Spettroscopie Non-Lineari (Italy)
Costanza Toninelli , LENS - Lab. Europeo di Spettroscopie Non-Lineari (Italy)

Published in SPIE Proceedings Vol. 10683:
Fiber Lasers and Glass Photonics: Materials through Applications
Stefano Taccheo; Jacob I. Mackenzie; Maurizio Ferrari, Editor(s)

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