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Achieving rapid spectroscopic characterization is highly desirable for contactless, real‐time monitoring applications. However, it is challenging due to the trade‐off between short acquisition time and fine resolution. To address this challenge, a fully active scanning Fourier transform spectrometer (FTS) using thin‐film lithium niobate (TFLN) photonics is proposed. This work theoretically reveals relations between acquisition time and resolution and finds that their trade‐off can be notably alleviated by employing Michelson interferometer architectures. The proposed device consists of two broadband edge couplers and a tunable Michelson interferometer which includes 1.02 m‐length equivalent waveguides. The fabricated waveguides can achieve a wafer‐scale optical propagation loss of 12 ±$\pm$ 2.4 dB m−1${\rm m}^{-1}$, which enables the device to maintain a low insertion loss with a 1.02 m‐length equivalent waveguide. The proposed device can achieve an acquisition time of 10 μs$\umu{\rm s}$, a spectral resolution of 0.74 cm−1${\rm cm}^{-1}$ (i.e., 0.19 nm), and an operation wavelength range from 1260 to 1600 nm. [ABSTRACT FROM AUTHOR]

Frequency‐modulated continuous‐wave (FMCW) light detection and ranging (LiDAR) has a huge potential for developing the next generation of LiDAR applied in autonomous driving, industrial automation, environmental monitoring, and so on. An ideal laser for the FMCW LiDAR system should simultaneously feature fast chirp repetition frequency, a large chirp bandwidth, high linearity, a compact footprint, and low‐cost. In this study, such a laser based on thin‐film lithium niobate (TFLN) photonics is proposed and demonstrated. The laser can achieve a chirp bandwidth of 3.44 GHz, a tuning efficiency of 574 MHz V−1, and a chirp rate of 3.44 × 107 GHz s−1, which are the best values compared with other TFLN‐based lasers. A FMCW LiDAR system built by their laser is also experimentally demonstrated, showing that it can achieve a ranging precision of 4.9 mm, a velocity precision of 0.054 m s−1, and a sampling rate of 5 MSa s−1. [ABSTRACT FROM AUTHOR]

We demonstrate a circulator-free thin-film lithium niobate (TFLN) dispersion compensator based on the cascading 2 × 2 multimode interferometer (MMI) and two identical chirped Bragg gratings (CBGs). The cascaded MMI-CBG structure provides a dispersion value of 920 ps/nm/m over a 20 nm bandwidth covering 1537 to 1557 nm, featuring a compact footprint of 1 mm × 0.7 mm. Utilizing this device within a TFLN electro-optic time-lens system, we successfully generate 863-fs pulses at a 37 GHz repetition rate. Our compact, scalable, low-loss, and circulator-free dispersion compensator is the building block for the efficient generation of high-peak-power femtosecond laser pulses.

We propose a rapid and precise scheme for characterizing the full-field frequency response of a thin-film lithium niobate-based intensity modulator (TFLN-IM) via a specially designed multi-tone microwave signal. Our proposed scheme remains insensitive to the bias-drift of IM. Experimental verification is implemented with a self-packaged TFLN-IM with a 3 dB bandwidth of 30 GHz. In comparison with the vector network analyzer (VNA) characterization results, the deviation values of the amplitude-frequency response (AFR) and phase-frequency response (PFR) within the 50 GHz bandwidth are below 0.3 dB and 0.15 rad, respectively. When the bias is drifted within 90% of the V π range, the deviation fluctuation values of AFR and PFR are less than 0.3 dB and 0.05 rad, respectively. With the help of the full-field response results, we can pre-compensate the TFLN-IM for the 64 Gbaud PAM-4 signals under the back-to-back (B2B) transmission, achieving a received optical power (ROP) gain of 2.3 dB. The versatility of our proposed full-field response characterization scheme can extend to various optical transceivers, offering the advantage of low cost, robust operation, and flexible implementation.