The performance of a chirped waveguide grating as a wavelength demultiplexer has been investigated. Considerations include TE-‘LX, TE-TM and TM-TM mode coupling for different incident angles and waveguide parameters. The spectral response of the chirped sinusoidal surface relief grating in the optical waveguide has been studied by means of Local Normal Mode Expansion (LNME) theory to account fo...