We demonstrate that commercially available poly(D,L-lactic acid) (PDLLA) is a suitable material for the fabrication of biodegradable optical fibers with a standard heat drawing process. To do so we report on the chemical and optical characterization of the material. We address the influence of the polymer processing on the molecular weight and thermal properties of the polymer following the preparation of the polymer preforms and the fiber optic drawing process. We show that cutback measurements of the first optical fibers drawn from PDLLA return an attenuation coefficient as low as 0.11 dB/cm at 772 nm, which is the lowest loss reported this far for optical fibers drawn from bio-resorbable material. We also report on the dispersion characteristics of PDLLA, and we find that the thermo-optic coefficient is in the range of −10 −4°C−1. Finally, we studied the degradation of PDLLA fibers in vitro, revealing that fibers with the largest diameter of 600 µm degrade faster than those with smaller diameters of 300 and 200 µm and feature more than 84% molecular weight loss over a period of 3 months. The evolution of the optical loss of the fibers as a function of time during immersion in phosphate-buffered saline indicates that these devices are potential candidates for use in photodynamic therapy-like application scenarios.

The limited penetration depth of visible light in biological tissues has encouraged researchers to develop novel implantable light-guiding devices. Optical fibers and waveguides that are made from biocompatible and biodegradable materials offer a straightforward but effective approach to overcome this issue. In the last decade, various optically transparent biomaterials, as well as different fabrication techniques, have been investigated for this purpose, and in view of obtaining fully fledged optical fibers. This article reviews the state-of-the-art in the development of biocompatible and biodegradable optical fibers. Whilst several reviews that focus on the chemical properties of the biomaterials from which these optical waveguides can be made have been published, a systematic review about the actual optical fibers made from these materials and the different fabrication processes is not available yet. This prompted us to investigate the essential properties of these biomaterials, in view of fabricating optical fibers, and in particular to look into the issues related to fabrication techniques, and also to discuss the challenges in the use and operation of these optical fibers. We close our review with a summary and an outline of the applications that may benefit from these novel optical waveguides.

We report on the first step-index biodegradable polymer optical fiber (bioPOF) fabricated using commercially available polyesters, with a core made from poly(D,L-lactic-co-glycolic acid) and a cladding made from poly(D,L-lactic acid). We prepared the preforms with a rod-in-tube technique and the fibers with a standard heat drawing process. We discuss the chemical and optical properties of the polyesters along the fabrication process from polymer granulates to optical fiber. More specifically, we address the influence of the processing steps on the molecular weight and thermal properties of the polymers. Cutback measurements return an attenuation of 0.26 dB/cm at 950 nm for fibers with an outer diameter of 1000 ± 50 µm, a core of 570 ± 30 µm, and a numerical aperture of 0.163. When immersed in phosphate-buffered saline (PBS), bioPOFs degrade over a period of 3 months, concurrent with a 91% molecular weight loss. The core decomposes already after three weeks and features 85% molecular weight loss. There is no any additional optical loss caused by immersion in PBS during the first 30-40 min for a bioPOFs with a diameter of about 500 µm. Our result demonstrates that bioPOF can be suitable for

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