All-Biodegradable Agar-Core, Agar-Cladding Optical Fiber

This paper reports a multimode optical fiber with core and cladding made of agar, a biodegradable and edible material. This waveguide has singular characteristics, such as reversible thermal gelation and moldability, and adjustable properties like refractive index and core/cladding diameters. Moreover, the fibers are biocompatible and present a low-cost and straightforward fabrication. We fabricate the cladding using a dip coating technique. Submerging a no-core agar fiber into melted agar-glycerol solutions with lower refractive indexes produces a surrounding layer with adjustable thickness. We characterized the optical loss through the cut-back technique, achieving 0.35 dB/cm at 632 nm. Results are comparable to other biodegradable waveguides, which suggests further applications in sensing, imaging, and illumination.