The properties of a step index Bragg grating formed by uniformly spaced layers of GaAs and Al,Ga As are evaluated by illuminating it with broadband light and measuring the spectrum of reflected light. A Bragg peak with maximum reflectivity of 5% is found at 900 nm , and the first zero reflection near the Bragg peak is located at 960 nm. GaAs is known to have n = 3.6, but the refractive index of the Al,Ga As layers is unknown. Determine (a) the spacing between layers, (b) the number of layers, and (c) the refractive index of the Al,Ga As layer:s. 8.4 reflectivity first zero reflection near