Single‐Mode, 700%‐Stretchable, Elastic Optical Fibers Made of Thermoplastic Elastomers

Optical fibers made of thermoset elastomeric materials can offer extremely high stretchability not possible with conventional glass and plastic optical fibers. However, such elastomer fibers have so far been made with large mm‐scale diameters, which limit their potential utilities. Here, fabrication of small‐diameter (< 200 µm), core‐clad optical fibers using a thermal drawing of transparent thermoplastic elastomers is demonstrated. The single‐mode optical fibers fabricated by this method are highly elastic and durable against strain up to 700%. Furthermore, a composite thermoplastic‐thermoset elastic optical fiber is also presented, in which the advantageous properties of both families of elastomers are combined. These optical fibers may be useful for short‐distance, mechanically flexible, optical interconnections in biomedical, wearable, or implantable photonic devices. Small‐core super‐elastic optical fibers are realized by thermal drawing of core‐clad fiber preforms made from transparent thermoplastic elastomers. Such fibers can guide single‐mode light and their optical properties depend on the fiber strain. Furthermore, a new composite fiber by combining the favorable properties of thermoset and thermoplastic stretchy polymers is presented.