Enhanced directional emission of monolayer tungsten disulfide (WS2) with robust linear polarization via one-dimensional photonic crystal (PhC) slab

Abstract

Abstract Objectives Monolayer transition metal dichalcogenides (TMDCs) have been regarded as promising candidates for the future light-emitting devices. To date, though the modulation of emission intensity and directionality in monolayer TMDCs has received considerable scholarly attention, there has been no systematic investigation on the underlying critical polarization. The intensity, directionality and robust polarization are highly favorable and pivotal for the future on-chip optoelectronic emission devices based on TMDCs. Methods We explore the emission features of the monolayer TMDCs in the photonic crystal (PhC) platform at room temperature. A monolayer tungsten disulfide (WS2) is specifically integrated with a tailored PhC structure. Angle-resolved photoluminescence (PL), time-resolved PL and polarized PL measurements are carried out to study the enhanced emission and polarization properties. Results The photoluminescence (PL) of WS2 is greatly enhanced by over 300-fold, resulting from a ∼fivefold enhancement (from 1.5 to 7.2%) of the PL efficiency with accelerated spontaneous emission rates. Additionally, the overall polarized emission is obtained with the degree of linear polarization (DLP) up to 60%, which is independent of the excitation polarization. Moreover, two branched directional emissions with horizontal polarization are also achieved at a divergency angle of only 3.5°, accompanied by a surprising near-100% DLP at ±8° directions. Conclusions This comprehensive study sets out to assess the feasibility of the high-performance light emission device based on the monolayer TMDCs and PhC structures.