2. Let's assume we have the process given by hi4 = w] + 1112 + 1113, i.e. a thirdorder nonlinear process in which three input elds {ail5 mg, 1.33) are transformed into one output eld with an. [15] a) Draw the photon diagram and discuss its meaning in detail. The nonlinear polarization for such a response of a XlSlmedia is given by PNL(w4 = as + as + 111.33) = gag-v map + 2|al|2 + 2|Ag|2 + 2|A3|2ji4eik4z + 2A1A2A35iik1+v+r . 'We further assume Xi?\" to be real. b) 'Write down the equation for the spatial evolution in zdirection of the generated eld A4{z). c) Discuss the meaning of the ve different terms obtained and explain to which term each of the photon diagrams from a) corresponds. d) Derive the spatial evolution of the intensity Ida) = 250n4c|14(z)|2 and simplify the expres sion as much as possible. e) Assuming photon number conservation, describe the evolution of the intensities of the other three intensities. i.e. .. and . ' d2: ' dz - dz T f j W hat relations have you derived for thirdorder nonlinear effects when performing the tasks above