Optical birefringence in strain tuneable silk fibroin whispering gallery mode cavities

Silk fibroin is a promising host biomaterial for the development of the forthcoming generation of wearable opto-electronic devices [1] ; also exhibiting interesting sensing functionalities [2]. Silk fibroin undergoes a unique structural transformation from the Silk I (amorphous) to the Silk II (semi-crystalline) structure; this transformation is accompanied by a number of distinct changes in the physical (i.e., wettability) and optical (birefringence) properties of this biomaterial, while being underlined by the augmentation of nano-crystalline β-sheet structures occurring in the Silk II structure.