Phase-gradient gap-plasmon metasurface based blazed grating for real time dispersive imaging

Dispersive Fourier transform imaging is a powerful technique in achieving ultrafast imaging of wide areas. However, system power efficiency is often limited by dispersive components. Here, we demonstrate that a gap-plasmon metasurface (GPM) based blazed grating can be used in dispersive imaging applications to achieve higher power efficiency than conventional gratings. A sub-wavelength GPM-based grating at telecommunication wavelengths has been designed and fabricated. 75.6% power efficiency with ∼0.4°/10 nm spatial dispersion has been measured for TE polarized waves at normal incidence. The fabricated device has been tested in a wide area real-time dispersive imaging system and <300 μm spatial resolution has been demonstrated experimentally.