Consider the transmittance through a Fabry-Perot interferometer as a function of the varia...

Consider the transmittance through a Fabry-Perot interferometer as a function of the variable wavelength λ of its input field. Show that the FWHM of the transmittance peaks is and the separation between transmittance peaks is λfsr = λ/m. (Here m = 2d/λ, where d is the length of the Fabry-Perot interferometer.)