Stimulated Brillouin scattering for microwave photonics

Exponential growth in wireless communications have created demand for broadband signal reception and processing. Photonics technology is a prime candidate for future telecommunication, radar, sensing, and signal processing technologies. To bring photonic-based microwave signal processing to the mainstream requires a reduction of the form factor. Integration microwave photonics is a route for achieving high-performance, low-cost, and small-footprint devices. Although microwave photonic devices can be tuned over a wide frequency range, the spectral resolution of most functions such as filters is too coarse for processing RF signals where the separation between adjacent information channels can be down to only a few tens of megahertz. Breaking this barrier, a number of integrated microwave photonic technologies with ultra-high spectral resolution has been recently reported. The chapter focuses on key advantages of harnessing stimulated Brillouin scattering in photonic circuits for microwave photonics, including ultra-narrow linewidth filters, versatile tunable delay line and phase shifters, and advanced instantaneous frequency measurement systems.