Towards the integration of nanoemitters by direct laser writing on optical glass waveguides

A major challenge towards nanophotonics is the integration of nanoemitters on optical chips. Combining the optical properties of nanoemitters with the benefits of integration and scalability of integrated optics is still a major issue to overcome. In this work, we demonstrate the integration of nanoemitters positioned in a controlled manner onto a substrate and onto an optical ion-exchanged glass waveguide via direct laser writing based on twophoton polymerization. Our nanoemitters are colloidal CdSe/ZnS quantum dots (QDs) embedded in polymeric nanostructures. By varying the laser parameters during the patterning process, we make size-controlled QDpolymer nanostructures that were systematically characterized using optical and structural methods. Structures as small as 17 nm in height were fabricated. The well-controlled QD-polymer nanostructure systems were then successfully integrated onto a new photonic platform for nanophotonics made of an ion-exchanged waveguide. We show that our QDs maintain their light emitting quality after integration as verified by photoluminescence (PL) measurements. Ultimately, QD emission coupled to our waveguides is detected through a home-built fiber-edge coupling PL measurement setup. Our results show the potential for future integration of nanoemitters onto complex photonic chips.