University of Malaya Photonics Research Centre Kuala Lumpur Malaysia
It is observed that the TM-light propagation loss is low for GO coating thickness up to 0.4 m. When the GO coating thickness is increased above 0.4 m, TM-light becomes unguided in the waveguide, resulting in an abrupt increase in propagation loss to more than 60 dBmm. On the other hand, the propagation loss of TE-polarised light increases to 44.6 dBmm in GO-coated waveguides with a 0.34 m GO coating - before decreasing to 14.2 dBmm in GO-coated waveguides with a GO coating thickness of 0.71 m. With the extinction coefficient profile of TM- and TE-polarised light of GO-coated waveguides with different GO thicknesses, the complex refractive index of GO coating is obtained using FEM analysis. The complex refractive index of our GO coating, with TE- and TM-polarised light, are 1.660.07i and 1.610.001i, respectively. The uncertainties of these values are smaller by an order of magnitude when compared to values measured using the conventional method of spectroscopic ellipsometry.