Paul W. K. Rothemund

Paul W. K. Rothemund

Departments of Computer Science, Bioengineering, and Computation & Neural Systems, California Institute of Technology
Paul W. K.  Rothemund

Plenary Talk 3: Integrating DNA Origami with Microfabricated Photonic Crystal Cavities 

A wide class of classical and quantum optical devices are based on the coupling of the electromagnetic field to individual atoms, molecules, quantum dots, or other emitters within nanofabricated optical cavities. The coupling efficiency, which can be precisely simulated using numerical codes, is primarily governed by the position of the emitter within the optical modes of the device. For example, the enhancement of an emitter's fluorescence is proportional to the mode-dependent local density of optical states (LDOS) via the Purcell effect. A number of existing experimental techniques variously combine AFM, SEM, and sophisticated lithography to position single emitters within single devices but currently there is no scalable technique to deterministically position emitters within nanooptical environments. This limits our ability to make and study devices based on cavity-emitter interactions---entire papers are often based around the performance of a single, heroically-fabricated device.

Here we experimentally demonstrate the deterministic coupling of fluorescent molecules to photonic crystal nanocavities (PCC) at a large scale. Individual DNA origami molecules carrying discrete numbers of fluorescent molecules are positioned with the resolution of e- beam lithography, in thousands of microfabricated devices. We first validated our approach by taking spectra of 21 different cavities in which each cavity featured an origami placed at a different position along the midline of the cavity. Periodic variation in the peak intensity of the emission demonstrated our ability to control emitter-cavity coupling by "walking" the origami in 50~nanometer steps through the modal pattern of the cavity. Next we used the the same technique to create a complete two-dimensional map of one mode of our PCCs with 25 nanometer resolution. For each of 600 precise x-y locations within the mode, a separate device was constructed having a DNA origami at location xy. The devices are arranged to recapitulate the xy position of the devices at a large scale, so that simple epifluorescence microscopy creates an "image" of the LDOS. Lastly, we demonstrate the programmability and scalability of our approach by building a 3-bit 65,536 nanocavity array in which the intensity of each pixel is independently programmed by controlling the location and number of molecules within a specific nanocavity.