High-efficiency polarization-independent diffraction by transmission grating with a connecting layer

We describe a novel transmission grating with a connecting layer to achieve high efficiency diffraction with polarization-independence. The grating duty cycle and period are optimized by modal method. Accurate grating depth and connecting layer thickness are optimized using rigorous coupled-wave analysis. High efficiencies of 99.21% for TE polarization and 99.12% for TM polarization can be achieved with the optimized grating parameters. Furthermore, the grating with a connecting layer can show efficiencies larger than 97% for both TE and TM polarizations within the given range of grating depth and connecting layer thickness, which will be significant for practical applications of such a high-efficiency polarization-independent grating with a connecting layer.

► A novel grating with a connecting Layer is proposed to obtain high efficiency.
► Efficiencies of 99.21% for TE and 99.12% for TM polarization can be achieved.
► The grating can show efficiencies larger than 97% within the parameters range.