Photonic Microwave Generation Using On-Chip Optical Frequency Combs

In our information society, the synthesis, distribution, and processing of radio and microwave signals happen ubiquitously in wireless networks, telecommunications, and radars. The current tendency is to use carriers in higher frequency bands, especially with looming bandwidth bottlenecks due to demands for 5G and the Internet of Things. Microwave photonics, a combination of microwave engineering and optoelectronics, might offer a solution.

A key building block of microwave photonics is optical frequency combs, which provide hundreds of equidistant and mutually coherent laser lines. They are ultrashort optical pulses emitted with a stable repetition rate that corresponds precisely to the frequency spacing of comb lines. The photodetection of the pulses produces a microwave carrier.