Reconfigurable photonic integrated circuits are the first evolutionary step in programmable photonics. These are fundamentally application-specific circuits designed to carry a given functionality and that feature some degree of flexibility enabled by the possibility of tuning some of its internal parameters by means of appropriate control signals. Another distinctive feature of these circuits resides in the fixed nature of their physical topology and designs. There is a vast amount of reconfigurable integrated circuits reported in the literature. This chapter provides some representative examples for other functionalities, including filtering, RF phase shifting and time delay lines, beam formers, wave generators and other multi-functional application specific circuits. It prepares the reader to understand how these can be emulated with the more generic programmable photonic circuits discussed later in the book.
Wafer-scale low-loss lithium niobate photonic integrated circuits