On the formation of white-light fringes in a mach-zehnder interferometer

Abstract

A theoretical investigation is made of the effects of dispersion in neutral gases on the formation of white-light fringes in an ideal Mach-Zehnder interferometer. It is found that the shift of the brightest fringe is determined by the change of the group refractive index at an effective mean wavelength of the white light. However, the white-light fringe technique may be used to measure changes of the phase refractive index, provided that an allowance is made for the drift of the brightest fringe caused by the effects of dispersion. Such allowance is needed whenever the fringe shift exceeds about 10.