On-chip low-loss all-optical MoSe2 modulator

Abstract

Monolayer transition metal dichalcogenides (TMDCs), like MoS2, MoSe2, WS2, and WSe2, 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- μ m-long Si3N4 waveguide-integrated all-optical MoSe2 modulator. Using this model, a switching energy of 14.6 pJ is obtained for a transverse-magnetic (TM) and transverse-electric (TE) polarized pump signals at λ = 480 nm. Moreover, maximal extinction ratios of 20.6 dB and 20.1 dB are achieved for a TM and TE polarized probe signal, respectively, at λ = 500 nm 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.