Ultra-Low-Loss Silicon Nitride Optical Beamforming Network for Wideband Wireless Applications

• Published in: IEEE journal of selected topics in quantum electronics Vol. 24; no. 4; pp. 1 - 10
• Main Authors: Yuan Liu, Wichman, Adam R., Isaac, Brandon, Kalkavage, Jean, Adles, Eric J., Clark, Thomas R., Klamkin, Jonathan
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2018; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Bandwidth; Bandwidths; Beamforming; Broadband; Delay; Delays; Dipole antennas; Genetic algorithms; Group delay; High-speed optical techniques; Integrated optics; Microwave photonics; millimeter wave communication; Millimeter waves; Nonlinear optics; Optical communication; Optical losses; optical ring resonators; Optical waveguides; phased arrays; photonic integrated circuits; Silicon nitride; Time lag; true time delays; Ultrawideband; Upconversion; Wireless networks
• ISSN: 1077-260X; 1558-4542; 1558-4542
• DOI: 10.1109/JSTQE.2018.2827786

Three optical ring resonator (ORR)-based integrated ultra-low-loss silicon nitride 1 × 4 optical beamforming networks (OBFNs) for millimeter-wave (mmW) beamsteering are reported. The group delay ripple of multi-ORR delay line was theoretically optimized and quantitatively studied by applying a genetic algorithm. The optimized 3-ORR delay true time delay (TTD) responses were experimentally achieved with 208.7 ps and 172.4 ps of delay tuning range for bandwidth of 6.3 GHz and 8.7 GHz, corresponding to a phase shift of 17.1π and 14.1π for 41 GHz mmW signal. The TTD performance of the 3-ORR delay line was also verified by controlling the delay of 3 Gbps data stream. A 22° beamsteering angle equivalent OBFN delay distribution was achieved for 41 GHz half-wavelength dipole antenna array. Both the theoretical analysis and experiments exhibit that the topology with one ring shared could balance the system complexity and TTD bandwidth well. Using heterodyne up-conversion technology and a single delay path, 41 GHz mmW signal with 3 Gbps OOK NRZ data modulation was generated and delayed.