The refractive index modulation depth in fiber core is the only parameter which affects FBG′s degeneration mechanism,so the effects of refractive index modulation depth on peak value and zero-crossing bandwidth are simulated.Based on the photon theory,the chain impact mechanism reveals that environmental impact causes electrons overflow which are of certain distribution of energy,and then causes the reduction of modulation depth,and eventually leads to the performance degeneration of FBG.The exp...