Fundamental Building Blocks for Scalable Photonic Programmable Processors

ABSTRACT Photonics technology is emerging as a key enabler, complementing electronics in next‐generation applications by offering greater bandwidth, lower latency and improved energy efficiency. Silicon photonic programmable processors bring these advantages to a solid‐state platform, providing compact form factors and low power consumption, although the scalability of densely integrated circuits is still under active investigation. In this article, we present a comprehensive study of the essential photonic components required for large‐scale integration of silicon photonic processors, covering both design and experimental demonstration. We analyse and optimise the fundamental building blocks—including splitters, phase shifters, and crossings—and experimentally validate their scalability through wafer‐scale characterisation. To finish, we illustrate the impact at the circuit level in a optical switch loaded with high‐speed transmission and discuss the remaining challenges for large‐scale integration.