Toward on-chip integration of linear optical wave energy redistribution systems for photonic signal processing [Invited]

Photonics signal processing has emerged as a promising technique for ultrafast optical and microwave signal processing. Among these, the linear optical wave energy redistribution (OWER) methodology offers unprecedented performance, such as low latency, ultrabroad operation bandwidth, and high energy efficiency. The OWER is based on linear phase manipulation techniques, e.g., the time lens and dispersive line, and can redistribute the energy of the optical waveform along the time domain to achieve user-defined signal processing functionalities. Here, we review recent OWER methods to provide an insight into this processing strategy, including photonic spectrograms for ultrafast optical and microwave signals and time-frequency manipulation for time-varying microwave waveforms. As current demonstrations of OWER systems are based on bulky, fiber-optics devices, the chip-scale implementation is desired to reduce the footprint, cost, and power consumption. Toward this end, we provide here an overview of the state of the art in integrated key photonic or optoelectronic components used in the OWER system, ranging from the most essential passive component, i.e., on-chip dispersive lines, to active devices, such as the modulators, integrated lasers components, and photodetectors.