Thin Receiver Freeform Lenslet Concentrator Array for LiFi

Emerging optical wireless communication (OWC) and LiFi require an ever-increasing bandwidth and decreasing size of the receiver modules compatible with mobile communication. This leads to using arrayed photodetector (PD) solutions for the receiver. However, the classical imaging solutions (e.g., convex lenses) struggle to achieve the required optical concentration at mobile form factors. In comparison, the non-imaging solutions (e.g., compound parabolic concentrators (CPCs)) provide poor uniformity of the irradiance distribution at the PD plane that can impair the link performance in the arrayed PD receivers. This paper proposes a novel approach using a freeform lenslet concentrator array to achieve an enhanced gain at a 5-degree field-of-view (FoV) compared to existing standard imaging optics solutions. The design also maintains a better irradiance uniformity and smaller refracted beam angle than the nonimaging solutions. Making it a promising optical solution that can help bridge the gap between imaging and non-imaging optics for high bandwidth arrayed PD receivers for mobile LiFi and OWC applications.