Light trapping structures are a promising approach to increase light absorption in ultrathin absorbers of interest for photovoltaic applications. To be integrated within real systems, their fabrication approach need to be simple and scalable, insuring that the gain in efficiency is worth the extra manufacturing steps. Here, we optimize through simulation using a RCWA code, a variety of 1D and 2D structures that can be fabricated with such simple and scalable techniques. In particular, we investigate the effect 1D and 2D gratings fabricated by Nanoimprint Lithography, onto Bragg mirrors that could be made using simple liquid process approaches. The optimized structures exhibit a significant gain in absorption with almost twice as much absorption in the wavelength range 0.5 to 1 micron, compared to a bare absorbing film of GaAs chosen as our reference. We also identify the various phenomena behind the absorption peaks observed and study the angular dependency of absorption with these structures.