Silicon-on-Insulator Microwave Photonic Filter With Widely Tunable and Reconfigurable Flat-Top Bandpass Functionality

We report of a silicon photonics (SiP) flat-top bandpass microwave photonic (MWP) filter with large out-of-band power rejection (OBPR) of up to more than 40 dB and exhibiting central frequency tunability over a range as large as 70 GHz, while still guaranteeing a minimum full-span OBPR larger than 25 dB. Furthermore, the RF bandpass transfer function can be widely configured without sacrificing the filter performance. In the present realization, a continuous bandwidth tuning from 5 to 10 GHz (corresponding to a 100% of bandwidth variation) is demonstrated. The operation is based on optical-to-RF mapping the response of a tunable and bandwidth reconfigurable photonic integrated optical filter, realized with a high-order distributed feedback resonator (DFBR) waveguide Bragg grating structure. A high level of functional integration is provided in a compact footprint of less than 2 mm(2) by embedding within the circuit a SiP phase modulator generating the modulation sideband scanning the DFBR filter, and a tunable optical splitter optimizing the MWP filter performance. Possibility of further extending system integration for monolithic on-chip operation is also investigated.

Automated summary

We report a silicon photonics flat-top bandpass microwave photonic filter with large out-of-band power rejection of over 40 dB and tunability of central frequency up to 70 GHz. The RF bandpass transfer function can be widely configured without sacrificing filter performance. The filter integrates a phase modulator and a tunable optical splitter to achieve a high level of functional integration.