Experimental demonstration of a wavelength demultiplexer based on negative-refractive photonic-crystal components

Negative refraction of light was observed at near-infrared wavelengths in a silicon-on-insulator photonic-crystal-slab superprism having low-loss interface structures. It was used for wavelength demultiplexing as a diffraction grating, in combination with a photonic-crystal superlens used for focusing light beams. Coarse wavelength demultiplexing action with a channel spacing of $7–27\mathrm{nm}$ was demonstrated in a device whose size was only $80\times 100\mu {\mathrm{m}}^2$ (excluding input and output waveguides). These results agree well with those obtained by a finite-difference time-domain simulation.