Conventional top-down nanofabrication, over the last six decades, has enabled almost all the complex electronic, optical and micro-fluidic devices that form the foundation of our society. Parallel efforts, exploring bottom-up self-assembly processes, have also enabled design and synthesis of structures like quantum dots, carbon nanotubes and unique bio-molecules that possess technologically relevant proper- ties unachievable top-down. While both these approaches have independently matured, ongoing efforts to create “hybrid nanostructures” combining both strategies, has been fraught with technical challenges. The main roadblock is the absence of a scalable method to deterministically organize components built bottom-up within top-down nanofabricated structures.
In this talk, I will first introduce a directed self-assembly technique that utilizes DNA origami as a molecular adaptor to modularly position, and orient, bottom-up nano-components (like quantum dots, light emitters and proteins) within top-down nanofabricated devices. I will then present experimental results demonstrating the utility of the technique to achieved absolute, arbitrarily scalable, control over the integration of discrete emitters inside optical devices. Finally, I conclude by presenting my vision of how a DNA origami based bridge between top-down and bottom-up nanofabrication can enable a range of highly transformative, and functional, devices. Specifically, I will present data demonstrating arrays of single-photon sources, method for extremely economical nanotexturing as well as a modular molecular interface between biology and solid-state.
Interfacing of single photon emitters, such as quantum dots, with photonic nanocavities enables study of fundamental quantum electrodynamic phenomena. In such experiments, the inability to precisely position quantum emitters at the nanoscale usually limits the ability to control spontaneous emission, despite sophisticated control of optical density of states by cavity design. Thus, effective light-matter interactions in photonic nanostructures strongly depend on deterministic positioning of quantum emitters.
In this work by using directed self-assembly of DNA origami we demonstrate deterministic coupling of quantum dots with gallium phosphide (GaP) dielectric whispering gallery mode resonators design to enhance CdSe quantum dot emission at 600nm-650nm. GaP microdisk and microring resonators are dry-etched through 200nm layer of gallium phosphide on silicon dioxide/silicon substrates. Our simulations show that such GaP resonators may have quality factors up to 10^5, which ensures strong light-matter interaction. On the top surface of microresonators, we write binding sites in the shape of DNA origami using electron beam lithography, and use oxygen plasma exposure to chemically activate these binding sites. DNA origami self-assembly is accomplished by placing DNA origami – quantum dot complexes into these binding sites. This approach allows us to achieve deterministic placement of the quantum dots with a few nm precision in position relative to the resonator. We will report photoluminescence spectroscopy and lifetime measurements of quantum dot – resonator deterministic coupling to probe the cavity-enhanced spontaneous emission rate. Overall, this approach offers precise control of emitter positioning in nanophotonic structures, which is a critical step for scalable quantum information processing.
The ability to reproducibly and accurately control light matter interaction on the nanoscale is at the core of the field of
optical biosensing enabled by the engineering of nanophotonic and nanoplasmonic structures. Efficient schemes for
electromagnetic field localization and enhancement over precisely defined sub-wavelength spatial regions is essential to
truly benefit from these emerging technologies. In particular, the engineering of deterministic media without translational
invariance offers an almost unexplored potential for the manipulation of optical states with vastly tunable transport and
localization properties over broadband frequency spectra. In this paper, we discuss deterministic aperiodic plasmonic and
photonic nanostructures for optical biosensing applications based on fingerprinting Surface Enhanced Raman Scattering
(SERS) in metal nanoparticle arrays and engineered light scattering from nanostructured dielectric surfaces with low
refractive index (quartz).