Sandhyarani,
The trial-90-112.fdt is not going to be a functional design. The field will inject from that z-directed input plane and propagate at a 90 which is straight up you will not get propagation to the nanowire and certainly will not get reflection and transmission of perpendicular propagation. The vertical configuration is what you should be using.
You have also not clarified why you are using a field that has a half-width of only 60nm.
You have posted a reference picture with no design context, I do not know what normalization or post processing was done on that or the structure it is modelling. Are you able to share the whole reference?
Scott