Mono-drive single-sideband modulation via optical delay lines on thin-film lithium niobate

Optical single-sideband (SSB) modulation features high spectral efficiency, substantial dispersion tolerance, and straightforward detection, making it a versatile technology for applications in optical communications, microwave photonics, optical sensing, satellite communication, etc. However, conventional SSB generators typically require two radio-frequency (RF) signals with a 90° phase difference to drive a pair of parallel phase or amplitude modulators, resulting in high system complexity and low power efficiency. In this paper, we propose and realize a simplified SSB generation scheme necessitating only a single RF drive by achieving effective RF phase shift using on-chip optical delay lines. This approach not only reduces system complexity and saves energy consumption by 3 dB but also enables easy scalability to higher frequencies. We demonstrate both full-carrier SSB (FC-SSB) and carrier-suppressed SSB (CS-SSB) modulation on a thin-film lithium niobate platform. For FC-SSB, we show a maximum sideband suppression of 22.1 dB at 50 GHz and apply it to address the frequency-selective power fading problem in optical communication systems. For CS-SSB, we show a maximum sideband suppression of 22.5 dB and a sideband-to-carrier suppression of 16.9 dB at 50 GHz, which can act as an optical frequency shifter by sweeping the modulation frequencies. Moreover, the shifted optical frequency can be transferred back to the electrical domain by beating with a reference signal generated via a phase modulator on the same chip, achieving broadband RF frequency shifting from a maximum of 50 GHz down to 1 GHz. Our simple, power-efficient, and low-cost SSB modulation scheme could provide an effective solution for future high-frequency direct-detection-based communication systems, frequency-modulated continuous wave radar/LiDAR, optical vector network analyzers, and microwave photonics systems.