Silicon photonic chip dynamically maps multiple Poincaré spheres

A fully tunable silicon photonic meta-generator has demonstrated dynamic control of structured light across more than eight Poincaré spheres, allowing independent manipulation of polarization and orbital angular momentum on a single chip. The peer-reviewed study, led by Minming Zhang and Shuang Zheng at Huazhong University of Science and Technology, combines inverse-designed multi-mode meta-waveguides with a multi-channel coherent amplitude-phase-polarization control circuit. In experiments, the device directed output fields toward arbitrary coordinates on polarization, orbital-angular-momentum, high-order and hybrid-order Poincaré spheres, while also synthesizing representative light fields within a four-dimensional parameter domain.

The system addresses limitations associated with conventional approaches to structured-light generation. Free-space setups commonly rely on spatial light modulators, multi-stage waveplate arrays and polarizers to produce vortex, vector and cylindrical vector beams, but these discrete components can require bulky optical paths, precise alignment and protection against environmental disturbances. Existing on-chip approaches have commonly used single-mode waveguide excitation, which restricts the diversity of output topological charges and can couple spatial wavefronts to polarization degrees of freedom. The researchers designed their chip to separate these functions while retaining a compact silicon-photonics platform.

At the input, a high-fidelity mode-conversion and multiplexing network converts selected higher-order waveguide modes, including TE0 and TE1, into independent coherent channels. Different guided modes have distinct dispersion characteristics, and the design uses this property together with inverse-optimized subwavelength meta-waveguide gratings. The result is simultaneous or selective emission of multimode orbital-angular-momentum beams with varying topological charges from one integrated aperture, expanding the accessible spatial modes beyond the single fundamental-mode output typical of many conventional on-chip generators. The device also integrates a thermo-optic phase-shifter array that independently controls the amplitude and relative phase of outgoing orthogonal components, enabling linear, circular and elliptical polarizations as well as inhomogeneous cylindrical vector fields.

By changing the electrical drive signals, the researchers altered the output Stokes parameters and steered and stabilized the optical states at selected points across multiple Poincaré spheres. They then coherently superimposed fundamental states extracted from different high-order Poincaré spheres to generate representative complex fields in a four-dimensional parameter domain. The demonstrated chip therefore provides programmable generation of high-dimensional structured light in a millimeter-scale silicon platform. The team identified space-division multiplexing communications, reconfigurable quantum photonics and custom topological optical structures, including optical skyrmions, as potential future applications. It also described future co-integration with high-speed modulators, laser sources, detectors and quantum emitters as a route toward a more self-contained structured-light system. The reported result is an experimental demonstration of multidimensional state generation; performance in complete communications, metrology or quantum-information systems was not established in the supplied research description.

Subject of Research: Experimental silicon-photonic control of multidimensional structured light across multiple Poincaré spheres

Article Title: Fully tunable on-chip meta-generator mapping multidimensional Poincaré spheres

Article References: Fully tunable on-chip meta-generator mapping multidimensional Poincaré spheres. Original publication (Bibliographic details unavailable.)

Image Credits: AI Generated

DOI: Not provided

Keywords: silicon photonics, structured light, Poincaré spheres, orbital angular momentum, polarization control, meta-waveguides, photonic integrated circuits, thermo-optic tuning, four-dimensional optics, quantum photonics, Fully, tunable