Integrated arrayed waveguide grating spectrometer for measuring Raman spectra

We designed a 3rd-order AWG using low-birefringence silicon oxynitride (SiON) waveguides with a SiO₂ cladding. The waveguide was chosen to have a cross-section of 2 μm x 0.52 μm, a core refractive index for TE polarization of 1.509 at 830 nm, and a cladding refractive index of 1.455. This choice results in the waveguides having zero birefringence at λ_c and low birefringence, Δn_eff,TM-TE = ±1.5 x 10^-4, at the edges of the Raman band of interest.