(Color online) Variation of the normalized intensity of HGBs with the normalized distance of propagation (ξ) for different orders of n (red, black and blue colors are for n = 1 , 2 and 3) keeping a 1 = 3 , a 2 = 2.4 , ω p 0 = 0.3 ω 2 , when relativistic and ponderomotive nonlinearities are operative. (a) and (b) are for first and second laser beam.