Integrated thin-film lithium niobate electro-optic frequency comb for picosecond optical pulse train generation

• Published in: Applied physics letters Vol. 124; no. 20
• Main Authors: Wang, Xuanhao, Li, Zhengkai, Chen, Junji, Shang, Chenglin, Zhang, Zhiyao, Li, Heping, Liu, Yong, Zeng, Cheng, Xia, Jinsong
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 13-05-2024
• Subjects: Analog to digital conversion; Broadband; Lithium niobates; Modulators; Optical communication; Optical frequency; Photonics; Pulse duration; Sampling; Thin films; Wavelength division multiplexing
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0206281

In recent years, high-performance thin-film lithium niobate (TFLN) electro-optic (EO) modulators boost the fast development of highly integrated, low loss, and large comb spacing EO frequency combs. Furthermore, ultra-short optical pulse trains (USOPTs) can be generated by the temporal domain compression of the optical frequency comb, which play an essential role in photonic sampling analog-to-digital conversion. Here, we demonstrate a flat and broadband EO frequency comb based on a packaged TFLN chip including a monolithic integrated intensity modulator, a phase modulator, and edge couplers. The 25 comb lines with a power fluctuation less than 3 dB are presented successfully. Moreover, we obtain a 10 GHz repetition rate USOPT, the pulse width of which is compressed to 2.67 ps. Our device may find its applications in the fields of ultrafast measurement, wavelength-division-multiplexing optical communication, or high-precision photonic sampling.