A tunable Si3N4 integrated true time delay circuit for optically-controlled K-band radio beamformer in satellite communication

In this paper we present the design, realization, and
experimental characterization of a photonic integrated true time
delay circuit on a CMOS-compatible Si3N4 platform. The true
time delay circuit consists of an optical side band filter for single
side band modulation and an optical ring resonator for broadband
time delay. Two methods of optical delay tuning are investigated:
1) optical wavelength and 2) thermo-optic delay tuning. The wavelength
controlled tuning enables a large delay tuning range and
can be done remotely from a distant location. The close to a linear
phase measurements can be used for full beam-scanning of radio
signals with frequencies in the 20 GHz band. The thermal control
results in a 5 GHz RF delay bandwidth. A proof-of-concept 2 × 1
beamforming is demonstrated in the 20 GHz band. The design presented
here can be employed to realize multi-beams for multi-users
serviced by multiple satellites.