Integrated Nonlinear Optical Signal Processing Devices and Applications(Invited)

Significance In recent years, global big data and network traffic have experienced explosive growth, and signal processing faces significant challenges in capacity and energy consumption. Currently, more than 90% of data information is transmitted via optical waves. As long as information processing is conducted using electronic devices, optical- electrical- optical (O- E- O) conversion is required. Compared to the processing speed of electronic devices, the bandwidth of optical signal transmission is significantly large. The signal should be demultiplexed into multiple low- rate signals, which can then be processed in the electrical domain to facilitate optical signal processing. However, demultiplexing and subsequent processing will increase the required number of O- E- O conversion devices, resulting in higher system complexity, costs, and energy consumption. On the other hand, optical nonlinear effects feature ultrafast response, large bandwidth, and parallelism, which can directly process high-speed- speed optical signals. Nonlinear optical signal processing (NOSP) is the process of employing optical nonlinear effects to process information. If efficient enough, NOSP has the potential to significantly reduce the cost and power consumption of network information exchange and processing. Unfortunately, NOSP usually requires high- power lasers since photons are bosons and the interactions between photons are usually weak. The interaction between light and matter should be enhanced to reduce power consumption. In recent years, the development of semiconductor integration technology has promoted the development of photonic devices toward integration. Photonic integrated devices feature low cost, low power consumption, light weight, high stability, and small size, which are beneficial for realizing more complex functional devices. Additionally, photonic integrated devices can localize the optical field in a very small area, greatly enhancing the interaction between light and matter. Meanwhile, integrated material platforms with high refractive indices have high nonlinear coefficients, making them suitable for developing NOSP devices and applications. In the early development of optical communication technology, communication capacity improvement relied on time division multiplexing. Researchers employed nonlinear effects to develop ultrafast optical switches for demultiplexing time division multiplexed signals. With the invention of optical amplifiers and the popularity of wavelength division multiplexing technology, NOSP applications such as all- optical wavelength conversion,