A Mechanophotonic Approach toward an Organic, Flexible Crystal Optical Interferometer

Abstract Organic crystals are poised to be a potential alternative to conventional silicon and its derivatives due to their utilization as microscale photonic components like active and passive waveguides, ring‐resonators, modulators, directional couplers, add‐on filters, interferometers (IMs), and reconfigurable circuits. Among these, IMs are important for flexible organic photonic integrated circuits. Here, the design and synthesis of extremely flexible ( E )‐1‐(((5‐bromopyridin‐2‐yl)imino)methyl)naphthalen‐2‐ol (BPyIN) crystals are demonstrated. The interactions stabilizing the crystal packing and crystal‐substrate adhesion dictate the elasticity and pseudo‐plasticity, respectively. The extremely flexible BPyIN crystals disclose bending geometry‐dependent optical modes in the fluorescence spectra. This understanding is extended for fabricating a fiber loop mirror (FLM)‐like geometry using a BPyIN single crystal. Mechanophotonics approach facilitates the integration of FLM‐like crystal with a doubly bent waveguide to construct a first‐of‐its‐kind IM. The light propagating path‐length‐dependent optical interference within the IM is established. These proof‐of‐principle experiments illustrate the usefulness of mechanophotonics to fabricate miniature photonic devices beyond the traditional fabrication approach.