Binary subwavelength grating with dynamic subperiod

The discussion on binary subwavelength gratings has recently been increased due to its simple fabrication procedure and potential applications in a variety of optoelectronic fields. Most designs of binary subwavelength gratings have been confined in the way that the grating ridges and/or channels are chirped and the defined grating period does not change during the design process. For some applications (e.g. interconnections), however, a dynamic diffraction pattern may be more desirable. In these cases, the variation of the diffraction angle and/or multiple diffraction beam pattern may be required. Therefor the rearrangement of the grating ridges and/or channels becomes a necessary. The newly arranged profile of the grating ridges and/or channels may be total different from the original one and may need to be changed into another profile later. This paper proposes a design method which optimize the diffraction efficiency at a desired angle and/or optimize the diffraction efficiencies at a multiangle pattern by forming a dynamic 'subperiod' within the initial defined grating period. Some design examples have been provided to prove the design concept.