Programmable photonic signal processor chip for radiofrequency applications

TL;DR

Existing integrated microwave-photonic demonstrations rely on application-specific chips, motivating programmable photonic processing. This paper introduces a two-dimensional mesh-network processor and demonstrates RF filters with continuous multi-octave tuning and variable passband shaping, while identifying scaling, frequency-resolution, and tuning-speed limits.

• Problem

  Existing on-chip photonic signal-processing demonstrations use custom application-specific circuits, motivating a programmable alternative to reduce fabrication cost and delay.

• Method

  The paper implements a programmable processor using tunable Mach-Zehnder couplers in a two-dimensional mesh, programming cascaded ring resonators to generate RF filters.

• Results

  The two-cell processor demonstrates RF filters with continuous tuning from 1.6 to 6 GHz and passband shaping from a 55-dB-extinction notch filter to a 1.6-GHz-bandwidth flat-top filter.

• Takeaways & Limitations

  The demonstrated programmable chip provides flexible RF filtering and supports the development of more powerful photonic signal-processing engines.

• Takeaways & Limitations

  Scaling the mesh network increases calibration and control effort exponentially, while thermo-optical tuning limits programming speed to milliseconds and sharper resolution depends critically on laser quality.