Hybrid Bioinspired Strongly Coupled Waveguides Using Optically Manipulated Micro-Robots

Bioinspired organic waveguides of mesoscopic length scales have established a new paradigm in photonics with possible applications in precision bioimaging, sensing, and diagnostics. However, the waveguides typically have low-quality factors (Q), which limits their applications significantly. We use optical tweezers to trap and configure spherical micro-robots so that they are attached to a single stationary organic waveguide. Fascinatingly, we observe that a microtube which was erstwhile supporting longitudinal cavity modes now supports transverse modes that propagate along its surface, and have a quality factor higher by a factor
$\sim$
7. Attachment of more micro-robots does not increase the Q due to disruptions in the momentum matching conditions that tend to inhibit nearfield evanescent coupling-based excitation of the transverse modes into the robots, and consequently, damping losses tend to dominate the final output. The experimental results were verified with FDTD-based simulations and achieved good agreement, thus establishing the robustness of the coupling mechanism. To the best of our knowledge, such enhancement of the performance of bio-inspired optical resonators using optical engineering is unprecedented, and may improve their capabilities and application space significantly.