Printing photonic devices from nanocrystals with light
Miniaturization of waveguides for confining and transporting light could usher in a new era of information technologies—photonics—based on light instead of electrons. Most photonic devices rely on very expensive fabrication processes adopted from the semiconductor industry. Talapin and Park have now demonstrated a way to produce on-chip waveguides with high resolution using inexpensive nanocrystal “inks” and direct optical lithography techniques.
Nanocrystals are deposited with crosslinking molecules from solution into smooth films a few hundred nanometers thick that are illuminated with ultraviolet light using a photomask to form photonic microstructures. Complex device geometries are already achievable with micron-level resolution, such as ring resonators, optical filters, and beam splitters; additionally, different materials, including high-refractive-index materials such as GaP, can easily be patterned and coupled to each other. Nanocrystal layers are also intrinsically porous, and their waveguides can be co-patterned with guest molecules such as dyes. ZrO2 ring resonators incorporating Rhodamine B made by this process, when illuminated with high-intensity yellow light pulses, demonstrate laser action.
Wu, H. Hong, Y.-C. Liu, Z. Zhou, T. Chen, Y. Zhang, S. Marder, J. Park, and D. V. Talapin, “Direct optical lithography of colloidal nanoparticles for on-chip photonics”, manuscript in preparation.