Low-Loss Wavelength-Selected Tunable Optical Delay Lines for Microwave Photonic Signal Processing

We propose and demonstrate a programmable low-loss 16-channel silicon-based microwave photonic signal processor using elliptical microrings and delaylines. The ellipital microrings offers flat-top filtering response to select/combine the carrier wavelength of the input optical signal. The following sixteen-channel delaylines are realized by ultra-low-loss broadened waveguides and low-phase-error Mach-Zehnder interferometer for 3.2 ps time-delay step. The overall insertion loss of the processor including the fiber-to-chip coupling loss is 10 dB. This programmable silicon photonic processor is demonstrated successfully to verify several microwave photonic signal processing functionalities: tunable delay line, beam beamforming and tunable radio-frequency filtering.