All-optical nonreciprocity due to valley polarization pumping in transition metal dichalcogenides

Abstract

Nonreciprocity and nonreciprocal optical devices play a vital role in modern photonic technologies by enforcing one-way propagation of light. Here, we demonstrate an all-optical approach to nonreciprocity based on valley-selective response in transition metal dichalcogenides (TMDs). This approach overcomes the limitations of magnetic materials and it does not require an external magnetic field. We provide experimental evidence of photoinduced nonreciprocity in a monolayer WS2 pumped by circularly polarized (CP) light. Nonreciprocity stems from valley-selective exciton population, giving rise to nonlinear circular dichroism controlled by CP pump fields. Our experimental results reveal a significant effect even at room temperature, despite considerable intervalley-scattering, showing promising potential for practical applications in magnetic-free nonreciprocal platforms. As an example, here we propose a device scheme to realize an optical isolator based on a pass-through silicon nitride (SiN) ring resonator integrating the optically biased TMD monolayer.

High output mode-locked laser empowered by defect regulation in 2D Bi2O2Se saturable absorber

“…However, SESAM requires sophisticated fabrication and exhibits narrow nonlinear optical bandwidths, which results in a narrow wavelength tuning range 6 . 2D materials, such as graphene 7 , 8 , transition metal dichalcogenides (TMDs; e.g., MoS 2 and WS 2 ) 9 – 12 , MXene 13 and topological insulators (TIs; e.g., Bi 2 Se 3 and Sb 2 Te 3 ) 14 , have been demonstrated to present broadband response wavelengths, while flexibility and atomic smooth surfaces make them easy to integrate in device fabrication. This renders 2D materials promising candidates for SA in the development of pulsed lasers 15 , 16 .…”

Low-Symmetry Nanophotonics

“…All of these approaches are based on the use of a magnetic field, either in the form of external bias or built-in. However, there is a need for non-magnetic insulators and circulators using other approaches to electromagnetic field nonreciprocity, including space-time modulation [221][222][223][224] , synthetic magnetic field [224][225][226] , nonlinearity [227][228][229][230] , interband photonic transitions 231,232 , optomechanics [233][234][235][236][237] , optoacoustics 238,239 , valley polarization in transition metal dichalcogenides 240 , and PT-symmetry breaking [241][242][243] .…”

Optically induced static magnetic field in ensemble of nitrogen-vacancy centers in diamond

“…Optically inducing a magnetic field is a promising route for generating high gradient magnetic fields and nanoscale on-chip excitations with a fast temporal response. For example, magneto-optical Barnett effect uses circularly polarized light to switch magnetization in magnetic thin films using ultrafast optical pulses [1,2], valley-selective optical pumping can induce nonreciprocity in transition metal dichalcogenides [3], while structured light can be used to induce a magnetic field by shaping optically induced currents [4]. Recently it was shown that a single nitrogen-vacancy (NV) center can probe an effective static magnetic field induced by the photonic spin density (PSD) of an optical beam [5].…”