Monolayer semiconductor nanocavity lasers with ultralow thresholds

Abstract

Engineering the electromagnetic environment of a nanometre-scale light emitter by use of a photonic cavity can significantly enhance its spontaneous emission rate, through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter, providing a low-threshold laser system with small footprint, low power consumption and ultrafast modulation. An ultralow-threshold nanoscale laser has been successfully developed by embedding quantum dots into a photonic crystal cavity (PCC). However, several challenges impede the practical application of this architecture, including the random positions and compositional fluctuations of the dots, extreme difficulty in current injection, and lack of compatibility with electronic circuits. Here we report a new lasing strategy: an atomically thin crystalline semiconductor--that is, a tungsten diselenide monolayer--is non-destructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PCC. A continuous-wave nanolaser operating in the visible regime is thereby achieved with an optical pumping threshold as low as 27 nanowatts at 130 kelvin, similar to the value achieved in quantum-dot PCC lasers. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within one nanometre of the PCC surface. The surface-gain geometry gives unprecedented accessibility and hence the ability to tailor gain properties via external controls such as electrostatic gating and current injection, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.

Advanced photonic filters based on cascaded Sagnac loop reflector resonators in silicon-on-insulator nanowires

“…With enhanced light trapping, there are increased time delays and enhanced light-matter interactions, which are useful in nonlinear optics and laser excitation. 10,11,27,28 In Fig. 5(c), one can see that there are central transmission peaks induced by an additional phase shift along L 4 , which correspond to a group delay 2.1 times higher than that of the CSLR resonator without the additional phase shift in Fig.…”

“…In addition, unlike the nearly uniform field distribution in TW resonators, the spatially dependent field distribution in SW resonators is useful for the efficient excitation of laser emission and nonlinear optical effects. [24][25][26][27][28] a Author to whom correspondence should be addressed: dmoss@swin.edu.au In this paper, we demonstrate advanced integrated photonic filters in silicon-on-insulator (SOI) nanowires by exploiting mode splitting in SW resonators formed by cascaded Sagnac loop reflectors (SLRs), which we term cascaded SLR (CSLR) resonators. We show that this is a powerful approach for engineering the spectral profile of on-chip filters.…”

Quantum emission from hexagonal boron nitride monolayers

“…These new atomically thin layers enabled realization of lasing from single monolayers 13 , generation of phonon polaritons [14][15][16] , super resolution imaging and spin valley transport [17][18][19] .…”

Graphene against Other Two-Dimensional Materials: A Comparative Study on the Basis of Photonic Applications

“…A continuous-wave nanolaser can operate in the visible regime using a monolayer based on a two-dimensional material as a gain medium with the aim of confining the direct band excitons within one nanometer of the surface of a photonic crystal cavity (PCC) [13]. An optical pumping threshold, as low as 27 nW at 130 K, must be used to stimulate the spontaneous emission of photons.…”