Dual-function beam splitter of high contrast gratings

We present the design and fabrication of a novel dual-function high contrast gratings that can be used as a polarization-selective beam splitter with transverse magnetic polarization, which performs two independent functions, i.e., reflection focusing and power equalization at a wavelength of 1550 nm. This dual-function grating profile is optimized by the rigorous coupled-wave analysis and the finite-element method. Simple analytical expressions of phase and modal guideline for the beam splitter design are given. The beam splitter based on the grating structure is experimentally studied at a distance of 160 μm from the reflection plane, the results are consistent with the theoretical results basically. (paper)