An interferometer is assembled as show . On one arm, a vertically polarized weak , field E1 interacts with a strong field E2, both with 1890nm wavelength, in a third order nonlinear crystal. On the other arm, the weak field becomes horizontally polarized and passes through a linear crystal with the same length and refractive index as the nonlinear crystal. The third-order susceptibility of the nonlinear crystal is ? (3)= 230 pm2/V2 , its refractive index is n0=1.5 and its length is L = 1 cm. Given that both arms have the same geometrical length, calculate the intensity of the field E2 for which the fields at the output ports of the interferometer become circularly polarized

E 2 E 1 X(3),n_Q lamda/2 (45) A B