Fabrication of Metallo-Dielectric Nanostructures

Nanophotonicstructures have recently generated a large amount of scientific interest due to their novel optical control and tunable properties. Most of these structures consist of large arrays of basic geometrical elements like dots, circles or lines etc. with a trend towards smaller dimensions and more densely filled lattices. Fabricating such subwavelength photonic structures for the visible or near infrared regime is a very challenging task. The most favoured method to fabricate such structures has been to use lithographic techniques like optical or electron beam lithography. These techniques consist of patterning the desired structure on a photoresist or e-beam resist followed by the development and subsequent plasma etching or metal deposition steps. Fabrication of high density waveguide like structures using E-beam Lithography is challenging due to concerns such as stitching errors and proximity issues which lead to irregularities in the fabricated structure. Continuous moving stage writing method is used to avoid the stitching errors for the long waveguide like structures but conventional proximity error correction methods cannot be applied in such cases. We propose a simple theoretical method to proximity correct these structures and experimentally demonstrate it in the case of a high density millimeter length waveguide like structures. Fabrication of a graded grating structure which will be used to study Plasmonic Bloch oscillation will be discussed. Plasmonic structures like Gratings and holes with different dimensions on a magnetic semiconductor quantum well structure is also fabricated where magneto-optical effects are expected to be significantly enhanced in such systems. Sub-wavelength gratings with different line-widths which are interesting for enhanced THz transmission were also fabricated.