Polarization-multiplexed nonlinear image processing in monolayer MoS2.

Parallel and reconfigurable all-optical image processing are two important goals in optical computing, yet existing schemes can only achieve one: metasurface-based approaches enable parallel processing but are not reconfigurable, while nonlinear-optics-based approaches allow reconfigurable operators but lack parallel capability. Here, we numerically demonstrate a polarization-multiplexed nonlinear image processing scheme based on sum frequency generation (SFG) in monolayer MoS2 and driven by a vector pump. Taking advantage of D3h symmetry of monolayer MoS2, the two orthogonal components of the vector pump beam can be independently designed to achieve two arranged image-processing operators in parallel. With a radial vector vortex pump, an isotropic edge map of the object is obtained directly, and continuous direction-tunable edge detection can be realized by rotating the polarization analyzer, which remains effective for arbitrary crystal orientations of monolayer MoS2.