On-chip low-loss all-optical MoSe$_2$ modulator

TL;DR

This paper presents a simple model for an on-chip all-optical MoSe2 modulator integrated with a Si3N4 waveguide, demonstrating low energy consumption, high extinction ratio, and ultrafast operation suitable for photonic applications.

Contribution

A novel simple model for MoSe2-based all-optical modulators is proposed, enabling efficient design and performance prediction of TMDC photonic devices.

Findings

Switching energy of 14.6 pJ at 480 nm

Extinction ratios over 20 dB at 500 nm

Ultrafast recovery time of 50 ps

Abstract

Monolayer transition metal dichalcogenides (TMDCs), like MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$, feature direct bandgaps, strong spin-orbit coupling, and exciton-polariton interactions at the atomic scale, which could be harnessed for efficient light emission, valleytronics, and polaritonic lasing, respectively. Nevertheless, to build next-generation photonic devices that make use of these features, it is first essential to model the all-optical control mechanisms in TMDCs. Herein, a simple model is proposed to quantify the performance of a 35$\,$\textmu m long Si$_3$N$_4$ waveguide-integrated all-optical MoSe$_2$ modulator. Using this model, a switching energy of 14.6$\,$pJ is obtained for a transverse-magnetic (TM) and transverse-electric (TE) polarised pump signals at $\lambda =\,$480$\,$nm. Moreover, maximal extinction ratios of 20.6$\,$dB and 20.1$\,$dB are achieved for a TM and TE polarised probe signal at $\lambda =\,$500$\,$nm, respectively, with an ultra-low insertion loss of $<0.3\,$dB. Moreover, the device operates with an ultrafast recovery time of 50$\,$ps, while maintaining a high extinction ratio for practical applications. These findings facilitate modeling and designing novel TMDC-based photonic devices.