# Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part 2: experimental prototype

L. Zhuang, C.G.H. Roeloffzen, Arjan Meijerink, M. Burla, D.A.I. Marpaung, Arne Leinse, M. Hoekman, Rene Heideman, Wim van Etten

139 Citations (Scopus)
An experimental prototype is presented that illustrates the implementation aspects and feasibility of the novel ring resonator-based optical beamformer concept that has been developed and analyzed in Part I of this paper . This concept can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The design, fabrication, and characterization of a dedicated chip are described, in which an 8$\times$1 optical beamforming network, an optical sideband filter for single-sideband suppressed carrier modulation, and a carrier re-insertion coupler for balanced optical detection are integrated. The chip was designed for satellite television reception using a broadband PAA, and was realized in a low-loss, CMOS-compatible optical waveguide technology. Tuning is performed thermo-optically, with a switching time of 1 ms. Group delay response and power response measurements show the correct operation of the OBFN and OSBF, respectively. Measurements on a complete beamformer prototype (including the electro-optical and opto-electrical conversions) demonstrate an optical sideband suppression of 25 dB, RF-to-RF delay generation up to 0.63 ns with a phase accuracy better than $\pi$/10 radians, and coherent combining of four RF input signals, all in a frequency range of 1–2 GHz.