Light trapping PMMA planar ridged waveguide on a laser textured silicon substrate for ultra-low reflectivity

Abstract

A novel composite total internal reflectance fiber structure on monocrystalline silicon (mono c-Si) constructed by specific micro-structures with base angle of 55 degrees and closely nested PMMA film is innovatively proposed to achieve a more effective sunlight trap for the first time. Besides the trapped light caused by multiple reflections on the laser textured surface, the total internal reflectance effect of light on the exiting surface of PMMA film is realized, which gains more times of reflection and absorption among the composite structure and further improves the anti-reflection effect. It’s found the reflectivities of the composite structures containing regular pyramid and V-shaped micro-structures have notably decreased to under 1.45% and 2.60% respectively in wavelength range of 350–1000 nm. This composite structure provides a new alternative and effective approach for the design and fabrication of silicon surface with ultra-low reflectivity.