i want to apply lighting effects for that shape.but before applying it. It is asking to rasterize the layer....can't we apply the effects directly to shape?
Right-click (Windows) or Control-Click (Macintosh) on the vector/shape layer (or any layer) and choose Convert to Smart Object from the contextual menu.
Then go ahead and choose Filter > Render > Lighting Effects. This will apply a Smart Filter to the Smart Object layer.
If you need to later edit the shape, simply double-click the Smart Object layer and it will open in a new window allowing you to edit the shape.