Waveguide-integrated microdisk lasers via ink-jet printing

Photonic integrated circuits provide a wide range of capabilities for customizable datacom as well as sensory systems in chemical and biological applications. However, the circuit integration of light sources, particularly lasers, remains challenging and costly. Here, we show how the emission from ink-jet-printed microdisk laser resonators can be coupled to a vertically stacked photonic integrated circuit. We print dye-doped microdisks with a lasing threshold below 100 µJ/mm² and realize vertical coupling of whispering gallery modes in wedge-shaped resonator geometries to silicon nitride waveguides employing accurate alignment in height and lateral dimensions. The ink-jet-printed disks can be doped with a wide variety of functional materials and allow for circuit reconfiguration, thus providing novel functionalities, including low-cost lasers, on a compact and stable chip platform for a wide range of applications.