Fabricating photonic crystal grating coupler for waveguides
Polymer gratings can efficiently couple a light into waveguides. Their coupling efficiencies strongly depends on their dimensions and refractive indices. The 1st order diffraction is used for coupling light into waveguides when the incidence angle of incoming light is matched for waveguiding. However, the guided intensity is weak compared to the incoming light intensity and needs to be improved. There are several reasons for the weak waveguide intensity: the 1st order diffraction intensity is weak compared the 0th order, low coupling efficiency, and guiding loss, among others. To optimize this couple, a number of experiments should be performed. The student researcher will first fabricate polymer gratings on the substrate using soft lithography. Then, the diffraction intensity of the 0th and 1st orders from He-Ne laser will be measured with varying incidence angles to determine maximum coupling conditions for different dimensions (height, pitch, structures) and materials.