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All-silicon polarized light source based on electrically excited whispering gallery modes in inversely tapered photonic resonators

: Schmitt, Sebastian; Schwarzburg, Klaus; Sarau, George; Christiansen, Silke; Wiesner, Sven; Dubourdieu, Catherine

Fulltext ()

APL materials 8 (2020), No.6, Art. 061110, 9 pp.
ISSN: 2166-532X
Journal Article, Electronic Publication
Fraunhofer IKTS ()
optical gain; emission; crystalline

As a result of its indirect bandgap, emitting photons from silicon in an efficient way remains challenging. Silicon light emitters that can be integrated seamlessly on a CMOS platform have been demonstrated; however, none satisfies an ensemble of key requirements such as a small footprint, room-temperature operation at low voltages, and emission of narrow and polarized lines with a high spectral power density in the near-infrared range. Here, we present an all-silicon electrically driven light emitting diode that consists of an inversely tapered half-ellipsoidal silicon photonic resonator containing a p-n junction used to excite whispering gallery modes (WGMs) inside the resonator. Under low voltage operation at room temperature, such a photonic silicon light-emitting diode exhibits a band-edge emission (900-1300 nm) with a wall-plug efficiency of 10(-4). The emitted spectrum is amplified in multiple WGMs and shows peaks that are polarized and have linewidths Delta lambda as narrow as 0.33 nm and spectral power densities as high as 8 mW cm(-2)nm(-1). Considering its small footprint of similar to 1 mu m and remarkable emission characteristics, this silicon light source constitutes a significant step ahead toward fully integrated on-chip silicon photonics.