Monolithically integrated vanadium oxide photodetection breaking spectral limitations

Abstract Ultra‐broadband photodetection spanning the visible to mid‐infrared spectrum is essential for spectroscopic applications. Miniaturizing spectroscopic systems into chip‐scale devices is highly desirable for portable and handheld applications in fields such as home healthcare, aerospace, and field experiments. However, achieving on‐chip ultra‐broadband photodetection remains a major challenge for integrated spectroscopic systems. Here, we demonstrate monolithically integrated ultra‐broadband vanadium oxide (VO x ) photodetection from visible to mid‐infrared wavelengths on a thin‐film lithium niobate (TFLN) platform. The VO x photodetection mechanism relies on the optical–thermal–resistance effect, with wavelength‐insensitive optical absorption enabling ultra‐broadband operation. The photodetector exhibits exceptional sensitivity, achieving a microwatt‐level detection limit due to the sharp resistance variation of VO x during its semiconductor‐to‐metal phase transition under minute temperature changes. With a compact micrometer‐scale footprint, the integrated VO x photodetector overcomes the typical speed limitations of thermal‐based detectors, delivering a fast response time of ∼26.24 μs. Furthermore, an 8‐unit detector array with uniform responses was demonstrated, highlighting its potential for chip‐scale ultra‐broadband spectrum analysis. The demonstrated hybrid TFLN‐VO x photodetectors thus pave the way for next‐generation miniaturized ultra‐broadband spectroscopic applications.