Beam Splitting Based on Connecting-Layer Grating with Improved Efficiency

The beam-splitting element is described based on the connecting-layer grating to improve the performance. A connecting layer is introduced between the grating region and the substrate. Efficiencies are improved especially for TE polarization. For TE polarization with the grating depth of 0.65 mu m and connecting layer thickness of 0.45 mu m, efficiencies of 49.50% and 49.53% can be diffracted into the -1st and the 0th orders, respectively. For TM polarization with the grating depth of 1.00 mu m and connecting layer thickness of 0.72 mu m, splitting efficiencies of 49.32% and 49.62% can be divided into the two orders.