Microring resonator-assisted Fourier transform spectrometer using thin-film lithium niobate

Fourier transform spectrometers (FTSs) are essential tools in fields such as nanotechnology, biological engineering, and chemical sensing. While integrated FTSs offer advantages such as scalability, low cost, and low power consumption, which make them widely adopted, it remains challenging to achieve an integrated FTS that simultaneously offers high resolution, fast acquisition speed, and a compact footprint. Here, we demonstrate an integrated Fourier transform spectrometer on a thin-film lithium niobate (TFLN) platform, which combines a thermally tunable microring resonator (MRR) with an electro-optically tunable Michelson interferometer (MI). This cascaded architecture shifts the resolution dependence from the optical path difference (OPD) in the MI to the full width at half maximum (FWHM) of the MRR, achieving an ultra-fine resolution of 58.7 pm within a compact footprint of 2.2 × 0.39 cm². The device also achieves a spectral acquisition time of 4 ms and an energy consumption as low as 0.3 mJ over a wavelength range from 1500 to 1600 nm. This approach enables high-resolution, high-speed, and low-power spectral measurements, offering a promising pathway for the development of next-generation integrated spectrometers.