Laterally confined photonic crystal surface emitting laser incorporating monolayer tungsten disulfide

Xiaochen Ge,Xiuling Li,Weidong Zhou,Momchil Minkov,Shanhui Fan

doi:10.1038/s41699-019-0099-1

Abstract

With an ultimately thin active region, monolayer transition metal dichalcogenide lasers have the potential of realizing ultralow lasing threshold and power consumption. The flexibility also enables integration possibilities on unconventional substrates. Here, we report a photonic crystal surface emitting laser using monolayer tungsten disulfide as the gain medium. The cavity design utilizes a heterostructure in the photonic crystal lattice to provide lateral confinement for a high quality factor with a compact active region. Room-temperature continuous wave lasing is realized after integrating monolayer tungsten disulfide flakes onto the silicon nitride photonic crystal on a quartz substrate. Highly directional, near surface-normal emission has also been experimentally demonstrated. The work reported here demonstrates that a large-area single-mode directional laser can be realized from a monolayer gain medium, which is critical for laser scaling for on-chip integration in data and sensing applications.

Highlights

As a direct bandgap semiconductor, monolayer transition metal dichalcogenide (TMDC) draws tremendous research interests, and numerous monolayer or few-layer TMDC-based lasers[1,2,3,4,5,6] and lightemitting diodes[7,8,9,10,11] have emerged recently
The lateral confinement is provided by the outer area of the photonic crystal (PhC) lattice with a reduced hole radius compared with the core region, which is denoted as the cladding
In agreement with previous reports,[1,5] we observed lasing on the longer-wavelength side of the monolayer WS2 PL spectrum

Summary

Introduction

As a direct bandgap semiconductor, monolayer transition metal dichalcogenide (TMDC) draws tremendous research interests, and numerous monolayer or few-layer TMDC-based lasers[1,2,3,4,5,6] and lightemitting diodes[7,8,9,10,11] have emerged recently. With an thin active region, TMDC lasers have the potential of realizing ultralow lasing threshold and power consumption. The flexibility enables integration possibilities on unconventional substrates.[12,13] The first demonstration of TMDC lasers is based on microdisk cavities[1,3] and photonic crystal (PhC) defect mode microcavities.[2] The emission wavelength is extended to near infrared by introducing molybdenum ditelluride (MoTe2) as the gain medium.[4,6] While offering a low threshold and high Purcell factor, the emissions from microcavities typically have a large divergence angle, which limits their application in practical devices due to the requirement of high-numerical aperture (NA)

Methods

Results

Conclusion