Mesh-Structure-Enabled Programmable Multitask Photonic Signal Processor on a Silicon Chip

Photonic integrated circuits (PICs) have recently attracted extensive attention in advanced photonic signal processing to meet the ever-increasing demands on high-speed and ultracompact data signal management. However, programmable and multitask photonic signal processing is still full of challenges, especially the scalable photonic integration solution. Here, we design, fabricate, and demonstrate a mesh-structure-enabled programmable multitask photonic signal processor on a silicon chip. It relies on a scalable 2D mesh structure network with a number of hexagonal unit cells formed by building blocks of tunable Mach-Zehnder interferometers (MZIs). We study several simple and complex optical filtering functions using configured single ring resonator, cascaded ring resonators, ring-assisted MZI, cascaded MZIs, reconfigurable and tunable comb filter and (de)interleaver, and double-injection ring resonators. For the proof-of-concept demonstration of on-chip programmable multitask photonic signal processing, a monolithically integrated silicon chip with four hexagonal unit cells is fabricated with greatly reduced geometric dimension. By appropriately adjusting the thermo-optic phase shifters of MZIs, versatile programmable multitask photonic signal processing functions are demonstrated in the experiment with impressive performance, including single ring resonator, cascaded ring resonators, asymmetric MZI, ring-assisted MZI, optical delay line, multiport router, and N x N optical switch. In particular, we also demonstrate the optical interference unit (OIU)-enabled self-configurable router and switch and their practical applications in fiber-optic communication systems. The demonstrations may open up new perspectives for on-chip solutions to ultracompact, reconfigurable, programmable, and multifunctional data signal management in advanced optical communication networks.