Ultra‐Fast, Fine‐Resolution Thin‐Film Lithium Niobate Spectrometer

Abstract 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 2.4 dB , 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 , a spectral resolution of 0.74 (i.e., 0.19 nm), and an operation wavelength range from 1260 to 1600 nm.