Integrated Photonic Orbital Angular Momentum Multiplexing and Demultiplexing on Chip

Abstract

Abstract : The work on this project focused on the design, fabrication, and demonstration of photonic integrated circuits (PICs) which create, multiplex, and demultiplex light beams with orbital angular momentum (OAM). Initial work on devices that manipulate the azimuthal OAM states included 2D silicon PICs for OAM state MUX/DEMUX that supported up to 65 OAM states and 2D silicon nitride PICs for OAM state MUX/DEMUX that supported up to 9 OAM states. Further, we fabricated and demonstrated hybrid devices based on 3D waveguide PICs coupled with 2D silica PICs that support 15 OAM states and both polarization states. We also developed devices that manipulated the radial OAM states using two different technologies; 3D stacking of 2D silicon nitride PICs and multi-ring 3D waveguide PICs coupled to two-layer 2D silicon nitride PICs. Multiple transmission link experiments were conducted using the fabricated OAM devices including freespace coherent communication link demonstrations utilizing polarization, frequency, quadrature and space dimensions to achieve a 1.68- Tb/s link bandwidth and a 9.6-b/s/Hz spectral efficiency. At the same time, photon-efficiency beyond 10 bpp is projected by combining the demonstrated 65 number of OAM states per ring and multi-ring 2D-3D OAM Mux/Demux technologies, while maintaining or suppressing the currently achieved 56 dB loss in the 2D-3D OAM Mux/Demux pair. We also demonstrated OAM state switching experiments and formulations of conceptual schemes for generating arbitrary spatial modes and including arbitrary waveform generation and detection in time, space, and spectral domains.