Triple-frequency signal generation based on a thin-film lithium niobate chip

We propose a photonic approach for generating triple-frequency signals utilizing a thin-film lithium niobate chip. Two optoelectronic oscillator (OEO) loops are established using phase modulators (PMs) and cascaded add-drop micro-ring resonators (MRRs) integrated on a single chip, resulting in the generation of two distinct frequency signals. Furthermore, the drop ports of the MRRs filter one sideband from each modulated signal, which are then combined to produce a third frequency through heterodyne beating. An experiment is conducted wherein signals at 9.31 GHz and 15.55 GHz, along with a sum-frequency signal at 24.86 GHz, are successfully generated. By adjusting the resonance wavelengths of two MRRs relative to the laser wavelength, signals with frequencies of 8.11 GHz, 28.30 GHz, and a difference-frequency signal of 20.19 GHz are also produced.