High Efficient Subwavelength Binary Blazed Grating Beam Splitter via Vertical Coupling

We propose a novel broadband beam splitter (BS) with a single-layer and compact grating vertical coupling structure, which is based on the form birefringence of subwavelength binary blazed grating and effective-medium theory. Rigorous coupled-wave analysis is used to optimize the design of this beam splitter. The simulation and analysis show that the BS for transverse electric (TE) light are designed to split the incident light beam into two beams of equal power (nearly 50% split), which travel in opposite directions in the waveguide. The coupling length is about 9 . The coupling efficiency for the right and the left branches of waveguide are 47% and 52%, respectively. The power difference of two output ports is less than 15% over a 75-nm wavelength bandwidth range.