Study of Subwavelength Gratings to Understand Their Polarization Behaviour

M. G. Sridharan[1], A. Prabhakar[2], and S. Bhattacharya[2]
[1]Photonics Group, Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, India
[2]Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai, India

Phase gratings are used in many applications owing to their high transmission and thus higher diffraction efficiencies. COMSOL is based on finite element modeling and is chosen for 2 reasons; firstly, because it can handle complex 2-D and 3-D geometries and secondly, it can handle the vector nature of these structures. The objective of the design is to compare the results of a commonly used analytical method with those obtained with the finite element model (FEM) of COMSOL.

The subwavelength binary phase gratings (PBS-A & PBS-B) act as polarizing beam splitters at Bragg incidence in the transmission end. Diffraction efficiency of TM and TE orders is in good accordance with the theoretical values. Hence COMSOL can be relied upon for vector models such as subwavelength grating and for far-field calculations; and extended to complex geometries.

Download