Widely tunable, low phase noise microwave source based on a photonic chip

Abstract

Spectrally pure microwave sources are highly desired for sev-eral applications, ranging from wireless communication to next generation radar technology and metrology. Additionally, to generate very pure signals at even higher frequencies, these ad-vanced microwave sources have to be compact, low in weight, and low energy consumption to comply with in-field applica-tions. A hybrid optical and electronic cavity, known as an opto-electronic oscillator (OEO), has the potential to leverage the high bandwidth of optics to generate ultrapure high-frequency microwave signals. Here we present a widely tunable, low phase noise microwave source based on a photonic chip. Using on-chip stimulated Brillouin scattering as a narrow-band active filter allows single-mode OEO operation and ultrawide frequency tunability with no signal degeneration. Furthermore, we show very low close-to-carrier phase noise. This Letter paves the way to a compact, fully integrated pure microwave source.