Tunable Single and Dual-frequency Optoelectronic Oscillator Incorporating a Single Cavity

Dual-frequency microwave signals with large and independent frequency tuning range are of fundamental interest for various applications, such as dual-band radar and wireless communication systems. In this paper, we propose and experimentally demonstrate a dual-frequency optoelectronic oscillator (OEO) capable of generating two microwave signals with independent tuning range within a single cavity, which is a scenario typically challenged by severe mode competition inside the cavity. We show that this mode competition can be overcome by finely adjusting the amplitude of two microwave photonic (MWP) filters to ensure the parity of two passbands. As a result, we simultaneously generate two microwave signals with independent tuning ranges spanning from 3.05 GHz to 3.96 GHz and 6.29 GHz to 7.41 GHz, respectively, each exhibiting a signal-to-noise ratio (SNR) exceeding 27 dB. Furthermore, utilizing the same structure, we also demonstrate a single-tone signal with a broad tuning range from 3.05 to 11.12 GHz, achieving an SNR surpassing 40 dB.