Wideband tunable optoelectronic oscillator based on stimulated Brillouin scattering and a Mach-Zehnder interferometer.

We propose a novel optoelectronic oscillator (OEO) based on stimulated Brillouin scattering (SBS) and a Mach-Zehnder interferometer (MZI). The SBS and MZI form a microwave photonic filter (MPF), which completes the frequency selection of the OEO. The width of the MPF passband can be changed by adjusting the DC voltage of the MZI. When the gap between the passbands is aligned with the side mode, the side mode can be suppressed; in this way, a single-mode optoelectronic oscillator is achieved. Compared with the previous structure, the proposed structure is more stable and easier to integrate. A stable frequency signal at 9.4 GHz is obtained with a phase noise of -84.05/ at 10 kHz, the side-mode-suppression ratio is 42 dB, and the frequency drift is below 50 kHz within 420 s. By adjusting the wavelength of the tunable laser source, a 280 MHz tuning range from 9.25 to 9.53 GHz is obtained. If an independent pump is introduced, a large tuning range is achieved from 9.4 to 24.9 GHz.