In the present paper, the study of the spectral and thermal sensitivities of the inorganic materials such as (Silica-doped, Lithium Niobate) materials and organic materials such as (PMMA Polymer) based waveguides employed in arrayed waveguide grating (AWG) in Passive Optical Networks (PONs) against spectral wavelength and ambient temperature variations. Moreover, we have investigated the best performance characteristics of the proposed three different fabrication materials based AWG for optical network applications over wide range of the affecting parameters. Key words: Passive optical networks, arrayed waveguide grating, spectral sensitivity, thermal sensitivity.