Optical slot antennas for enhancement of WSe<inf>2</inf> spontaneous emission rate

The spontaneous emission rate of light emitters has been shown to have strong dependence on their local electromagnetic environment <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sup> . Optical antennas exploit this effect and can be used to greatly increase the spontaneous emission rate of a coupled light emitter. There have been several demonstrations of this effect with promising results using dye molecules and Er <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> ions <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2,3</sup> . It is predicted that spontaneous emission rate enhancements greater than 1000x can be achieved with optical antennas while maintaining greater than 50% optical efficiency <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . Demonstration of large spontaneous emission enhancement of semiconductor light emitters could lead to low power, high efficiency, fast light sources useful for short-range optical communications. Transition metal dichalcogenides, such as WSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , are promising candidates for the light emitter of such a nanoLED device because they are semiconductors that maintain good quantum efficiency even with a nanoscale dimension. In this work we demonstrate an optical slot antenna coupled to a monolayer of WSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Photoluminescence measurements show an increase of total light emission >700x when compared to WSe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> that is not coupled to an antenna. We estimate a spontaneous emission rate enhancement of 318x is responsible for this huge increase in light emission.