Broadband, Polarization‐Insensitive Fourier Transform Spectrometer Based on Thin‐Film Lithium Niobate Photonics

Miniaturized Fourier transform spectrometers are pivotal for emerging applications in chemical sensing, biomedical diagnostics, and environmental monitoring. However, achieving broadband and polarization‐insensitive operation on a chip remains challenging. This work reports a thin‐film lithium niobate‐based Fourier transform spectrometer that overcomes this limitation via a polarization‐diversity architecture integrating edge couplers, broadband polarization splitters–rotators, and a Mach–Zehnder interferometer. The device operates over a 340‐nm bandwidth (1260–1600 nm) with a spectral resolution of 1.8 nm at 1550 nm. It enables high‐speed spectral acquisition with a 50‐µs acquisition time and an energy consumption of 4.59 µJ per acquisition. This work brings integrated Fourier transform spectrometers significantly closer to practical deployment in compact, low‐power, and polarization‐independent photonic systems.