Protein-Based Multi-Mode Interference Optical Micro-Splitters

Protein-based multi-mode interference optical micro-splitters (P-MMIs) were customized from bovine serum albumin aqueous ink by maskless and noncontact femtosecond laser direct writing. Good bio-/eco-compatibility could be achieved using protein-based biopolymers. As a premise of protein waveguide-based devices like P-MMIs, protein-based optical micro-waveguides were tested with
$\sim 0.059$
-dB/
$\mu \text{m}$
transmission loss for more bio-transparent 633-nm light. With satisfactory implementation of micro/nano-scale structure details, prototyping P-MMIs (two device geometries designed for 532 nm and 633 nm respectively) were fabricated and operated well as fundamental integrated optical devices for light splitting for the first time to our knowledge.