Effects of grating period and mode order on the growth and sensitivity of the resonant peaks of long period gratings

A general analytical expression for describing the growth of the resonant p eak wavelengths of long period gratings is derived. The theoretical calcula tions explain the shift of peak loss wavelengths in the direction of either shorter or longer wavelengths as the induced index change of grating incre ases. We have calculated and experimentally verified the sensitivity of the resonant peak wavelengths with respect to an overlay index for various gra ting periods. It is shown that the center wavelength shift of the claddding modes depends strongly on the grating period and the claddding mode order.