One important parameter to consider in the fabrication of solar cell devices is the optical absorption coefficient of the semiconducting material used. Efficient absorption of incident light by a solar cell enhances the generation of carriers in the photovoltaic material, which, in turn, contributes to achieving high conversion efficiency in the device. To improve light trapping in photovoltaic devices, surface texturing is crucial. This process significantly reduces optical losses, such as reflection and unabsorbed radiation. Surface texturing minimizes the substantial mismatch in the refractive index between the air and the photovoltaic material. This chapter provides a detailed discussion of the optical principles related to tuning the refractive index of photovoltaic materials and the process of surface texturing.