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Emission Engineering in Germanium Nanoresonators

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journal contribution
posted on 2015-01-21, 00:00 authored by Michele Celebrano, Milena Baselli, Monica Bollani, Jacopo Frigerio, Andrea Bahgat Shehata, Adriano Della Frera, Alberto Tosi, Andrea Farina, Fabio Pezzoli, Johann Osmond, Xiaofei Wu, Bert Hecht, Roman Sordan, Daniel Chrastina, Giovanni Isella, Lamberto Duò, Marco Finazzi, Paolo Biagioni
We experimentally investigate the smallest germanium waveguide cavity resonators on silicon that can be designed to work around 1.55 μm wavelength and observe an almost 30-fold enhancement in the collected spontaneous emission per unit volume when compared to a continuous germanium film of the same thickness. The enhancement is due to an effective combination of (i) excitation enhancement at the pump wavelength, (ii) emission enhancement (Purcell effect) at the emission wavelength, and (iii) effective beaming by the nanoresonators, which act as optical antennas to enhance the radiation efficiency. Our results set a basis for the understanding and engineering of light emission based on subwavelength, CMOS-compatible nanostructures operating at telecommunication wavelengths.