Numerical Investigation of Natural Light Transmission Through Fiber Optics

Fiber optics is a cutting-edge technology with boundless potential for transmitting natural light inside buildings. Imaging Solar concentrators are very efficient in focusing light within the approximate numerical aperture of fiber optics. The proof-of-concept of fiber optics concentration daylight systems was investigated and elaborated for only single-mode step-index fibers, and none of the previous studies had explored the full sun spectrum meticulously, the overall transmission efficiency, and the luminous output of such a system. The present research elaborates a detailed and exclusive numerical investigation of multi-mode-indexed fiber optics daylight systems. The proposed design consists of subsequent optical stages that focus light into the fiber optic cable, filter unwanted infrared wavelength radiation, and uniformly collimate visible light onto the fiber optics. The ray path and ray power intensities were traced and computed using the ray tracing technique. The obtained simulation results demonstrated an overall optical transmission efficiency of 32% along a 10 m length. The luminous efficacy of visible light transmission was evaluated based on the average illuminance levels inside buildings, indicating a substantial indoor lighting enhancement of 92 lumens/watt.