Photon polarization angular rotation divided by the amplitude of the detected GW, δβ/h0, in function of the decimal logarithm of the GW wavelength λg in meters (m), log10⁡(λg), equation (50). While the Idler arm length remains constant with Li  =  0,5 m, the three main peaks (red arrows) shift to higher GW wavelengths, as the large signal arm length increases from Ls  =  1.000 km, Ls  =  5.000 km, and Ls  =  10.000 km as shown in insets (a)–(c), respectively. In inset (c) one highlights the dependence of the first, second, and third peaks on the large signal arm length, i.e. 2Ls, 2Ls/3 and 2Ls/5, respectively, idem for the first, second, and third troughs, spotted with green arrows, and located at Ls, Ls/2 and Ls/3, respectively.