Cristian L. Cortes

Quantum nanophotonics using hyperbolic metamaterials

Engineering optical properties using artificial nanostructured media known as metamaterials has led to breakthrough devices with capabilities from super-resolution imaging to invisibility. In this paper, we review metamaterials for quantum nanophotonic applications, a recent development in the field. This seeks to address many challenges in the field of quantum optics using advances in nanophotonics and nanofabrication. We focus on the class of nanostructured media with hyperbolic dispersion that have emerged as one of the most promising metamaterials with a multitude of practical applications from subwavelength imaging, nanoscale waveguiding, biosensing to nonlinear switching. We present the various design and characterization principles of hyperbolic metamaterials and explain the most important property of such media: a broadband enhancement in the electromagnetic density of states. We review several recent experiments that have explored this phenomenon using spontaneous emission from dye molecules and quantum dots. We finally point to future applications of hyperbolic metamaterials, using the broadband enhancement in the spontaneous emission to construct single-photon sources.

Broadband super-Planckian thermal emission from hyperbolic metamaterials

We develop fluctuational electrodynamics of hyperbolic metamaterials (HMMs) and establish broadband near-field thermal emission beyond the black-body limit. We predict thermal topological transitions in phonon-polaritonic HMMs paving the way for near-field thermal engineering using metamaterials.

Applications of Hyperbolic Metamaterial Substrates

We review the properties of hyperbolic metamaterials and show that they are promising candidates as substrates for nanoimaging, nanosensing, fluorescence engineering, and controlling thermal emission. Hyperbolic metamaterials can support unique bulk modes, tunable surface plasmon polaritons, and surface hyperbolic states (Dyakonov plasmons) that can be used for a variety of applications. We compare the effective medium predictions with practical realizations of hyperbolic metamaterials to show their potential for radiative decay engineering, bioimaging, subsurface sensing, metaplasmonics, and super-Planckian thermal emission.

Enhanced and directional single-photon emission in hyperbolic metamaterials

We propose an approach to enhance and direct the spontaneous emission from isolated emitters embedded inside hyperbolic metamaterials (HMMs) into single-photon beams. The approach rests on collective plasmonic Bloch modes of HMMs, which propagate in highly directional beams called quantum resonance cones. We propose a pumping scheme using the transparency window of the HMM that occurs near the topological transition. Finally, we address the challenge of outcoupling these broadband resonance cones into vacuum using a dielectric bullseye grating. We give a detailed analysis of quenching and design the metamaterial to have a huge Purcell factor in a broad bandwidth in spite of the losses in the metal. Our work should help motivate experiments in the development of single-photon sources for broadband emitters such as nitrogen vacancy centers in diamond.

Photonic analog of a van Hove singularity in metamaterials

We introduce the photonic analogue of electronic Van Hove singularities (VHS) in artificial media (metamaterials) with hyperbolic dispersion. Unlike photonic and electronic crystals, the VHS in metamaterials is unrelated to the underlying periodicity and occurs due to slow light modes in the structure. We show that the VHS characteristics are manifested in the near-field local density of optical states inspite of the losses, dispersion and finite unit cell size of the hyperbolic metamaterial. Finally we show that this work should lead to quantum, thermal, nano-lasing and biosensing applications of van hove singularities in hyperbolic metamaterials achievable by current fabrication technology.

Thermal excitation of plasmons for near-field thermophotovoltaics

The traditional approaches of exciting plasmons consist of using electrons (eg: electron energy loss spectroscopy) or light (Kretchman and Otto geometry) while more recently plasmons have been excited even by single photons. A different approach: thermal excitation of a plasmon resonance at high temperatures using alternate plasmonic media was proposed by S. Molesky et.al., Opt. Exp. 21.101, A96-A110, (2013). Here, we show how the long-standing search for a high temperature narrow band near-field emitter for thermophotovoltaics can be fulfilled by high temperature plasmonics. We also describe how to control Weins displacement law in the near-field using high temperature epsilon-near-zero metamaterials. Finally, we show that our work opens up an interesting direction of research for the field of slow light: thermal emission control.

Corrigendum: Quantum nanophotonics using hyperbolic metamaterials (2012 J. Opt. 14 063001)

Engineering optical properties using artificial nanostructured media known as metamaterials has led to breakthrough devices with capabilities from super-resolution imaging to invisibility. In this paper, we review metamaterials for quantum nanophotonic applications, a recent development in the field. This seeks to address many challenges in the field of quantum optics using advances in nanophotonics and nanofabrication. We focus on the class of nanostructured media with hyperbolic dispersion that have emerged as one of the most promising metamaterials with a multitude of practical applications from subwavelength imaging, nanoscale waveguiding, biosensing to nonlinear switching. We present the various design and characterization principles of hyperbolic metamaterials and explain the most important property of such media: a broadband enhancement in the electromagnetic density of states. We review several recent experiments that have explored this phenomenon using spontaneous emission from dye molecules and quantum dots. We finally point to future applications of hyperbolic metamaterials, using the broadband enhancement in the spontaneous emission to construct single-photon sources.

Super-Coulombic atom–atom interactions in hyperbolic media

Dipole–dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole–dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom–atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon–polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.

Super-coulombic energy transfer: Engineering dipole-dipole interactions with metamaterials

We demonstrate experimentally that hyperbolic metamaterials fundamentally alter dipole-dipole interactions conventionally limited to the near-field. The effect is captured in long-range energy transfer and lifetime reduction of donor emitters due to acceptors placed 100 nm away.

Super-coulombic Van der Waals interactions in metamaterials (Presentation Recording)

We use Rytovs fluctuational electrodynamics to show that Van Der Waals interactions are fundamentally modified by metamaterials. We verify the conditions under which the effect is strongest and also show initial experimental results to prove the same. En route to developing the van der waals theory in metamaterials we have also adopted a unique approach to quantization in lossy dispersive media.