Experimental demonstration of nanophotonic devices and circuits with colloidal quantum dot waveguides

Colloidal quantum dots (CQDs) have been widely used as absorption or emission materials due to their large-absorption and high-gain properties. However, they are seldom used as low-loss materials in passive nanophotonic devices. Moreover, combinations of two or more properties of CQDs are difficult owing to miscibility of different CQDs. Here, low-loss CQD waveguides are experimentally achieved at wavelengths longer than their fluorescence wavelengths. By using the low-loss and uniform CQD waveguides, various passive nanophotonic devices and a nanophotonic circuit are successfully demonstrated. Furthermore, by employing both of a pattern-assisted stacking and a transfer-printing approach, the miscible problem of different CQDs is addressed, and a low-loss CQD waveguide and a high-gain CQD laser are experimentally integrated on a single chip.