Plasmonic transmitted optical differentiator based on subwavelength gold gratings

A nanoscale plasmonic optical differentiator based on subwavelength gold gratings is investigated theoretically and experimentally without Fourier transform lenses and prisms. In the vicinity of surface plasmon resonance (SPR), the transfer function of subwavelength gold gratings is derived by optical scattering matrix theory. Simulated by the finite difference time domain (FDTD) method, the wavelengths of optical spatial differentiation performed by subwavelength gold gratings are tuned by the grating period and duty cycle, while the throughput of edge extraction is mainly adjusted by the grating thickness. Without Fourier transformation, the fabricated plasmonic optical differentiator experimentally achieves real-time optical spatial differentiation in transmission and implements SPR enhanced high-throughput edge extraction of a microscale image with a resolution of 10 µm at 650 nm, which has potential applications in areas of optical analog computing, optical imaging, and optical information processing.