Generation of Gradient Index Optics with Subwavelength Metamaterials

Abstract

A GRIN optic is a useful device for modern optics but is not frequently used outside of niche applications due to the difficulty of fabricating any arbitrary gradient index. One potential solution to this fabrication problem is to use subwavelength metamaterials generated using lithography. A process was developed to generate a subwavelength waveguide which leverages effective medium theory to behave like a GRIN optic. This process was tested by generating waveguides as well as mode converters for converting from gaussian beams to supergaussian beams. The results from these experiments show that this technique could produce mode converters with average Strehl ratios of 0.997 and an average transmission of 94.8% on the scale of tens of microns; however, it was found that these designs are not viable for modern lithographic fabrication techniques. There is much to explore still with this topic such as the lower size limits of these designs or whether modern lithography could make a mode converter with this structure.