A system may include one or more electronic devices. Fiber bundles may be provided to convey light. A fiber bundle may have a bend along its length. Fibers for the fiber bundle may be formed from polymer cores coated with polymer claddings. The fibers may have end faces coated with antireflection coatings. The antireflection coatings may be formed from amorphous fluoropolymer deposited from solution. The fluoropolymer may be applied to the end faces of the fibers by dipping, spraying, or by dispensing with a needle dispenser or other dispensing tool. An optical component such as a light-emitting device for a communications system, an illumination system, or a sensor system may provide infrared light that is guided through the fiber bundle.