Ultra-broadband on-chip reconstructive spectrometer via controlled mode mismatch

We demonstrate a miniaturized reconstructive spectrometer based on a compact double-spiral, rounded-corner rectangular waveguide architecture. Bidirectional evanescent coupling enhances controlled mode mismatch, amplifying distinctions in wavelength-dependent signature patterns. Operating at 1565 nm center wavelength, the device achieves 0.08-nm resolution and 150-nm bandwidth (1490–1640 nm). Fabricated on silicon nitride, this structurally simple design facilitates integration into portable sensing platforms.