News

Selected news from NanoPhoton

 

Paper in Light: Science & Applications

Most theoretical derivations of fundamental radiative processes rely on energetic considerations and detailed balance equations, but not on momentum considerations. In this article we bring momentum exchange processes into consideration. It becomes very tricky in near-zero index (NZI) materials, i.e., materials having a phase refractive index close to zero. We theoretically demonstrate that momentum recoil, transfer momentum from the field to the atom and Doppler shift are inhibited in NZI materials. Fundamental radiative processes inhibition is also explained due to those momentum considerations inside three-dimensional NZI materials. We also discuss implication of NZI properties on consequence on the Heisenberg inequality, microscopy applications and diffraction pattern. Our findings give better understanding of fundamental light-matter interactions at the nanoscale as well as possibility of new lasing applications.

Momentum considerations inside near-zero index materials

 


 

Paper published in ACS Photonics

The team of Elizaveta Semenova demonstrated a novel InAs/InP Quantum Dot-based single photon emitter operating at the telecom C-band. A simple vertical emitting device possesses a photon extraction efficiency of ∼10% and high-purity single-photon generation ( g(2)(τ = 0) < 0.02 ) at the liquid helium temperature and preserved up to 50 K.

Bright Quantum Dot Single-Photon Emitters at Telecom Bands Heterogeneously Integrated on Si


 

Conference on "Fundamentals and applications of semiconductor nanocavities"

Last week NanoPhoton hosted a conference on “Fundamentals and applications of semiconductor nanocavities” with 24 international leading researchers joining for three days of very good and interesting talks and vivid and fruitful discussions. Thank you to all for making it a success.


 

Three PhD Students join NanoPhoton

 

 Kristian Seegert joined NanoPhoton on 1 March 2022. On 1 April 2022 Alexandra Palici and Frederik Schröder joined the centre. We look forward to the collaboration.


 

NanoPhoton Lecture: First-principles description of light-matter interactions in 2D materials by Kristian Sommer Thygesen

Kristian Thygesen develops and applies first-principles methods based on density functional theory and many-body perturbation theory to describe the electronic structure of materials with a particular focus on nanostructured and low-dimensional materials. He is also interested in the application of AI and data-driven approaches to materials design.

Two-dimensional (2D) materials, like graphene, hexagonal boron-nitride and the semiconducting transition metal dichalcogenides (TMDs), present exciting opportunities for creating new types of quantum states that can be manipulated with unprecedented accuracy and efficiency. In this talk I will demonstrate how excitons in TMD monolayers may be tuned via dielectric engineering [1] and how (mixed) interlayer excitons in TMD bilayers [2] may be controlled by application of a perpendicular electrical field. The spontaneous radiative emission from electronic transitions in 2D materials can be manipulated by engineering the electromagnetic vacuum field. I will show that record high Purcell enhancements of up to 10^7 can be achieved by coupling intersubband transitions in van der Waals quantum wells to the acoustic plasmons in a graphene sheet [3]. Finally, I will discuss how first-principles calculations can aid the discovery of crystal point defects in wide band gap semiconductors with potential application as single-photon sources, spin qubits or magnetic field sensing [4].


 

Paper on "Quantum theory of two-dimensional materials coupled to electromagnetic resonators"

Recently published in Physical Review B, NanoPhoton research headed by Emil Denning shows how a series of recent spectacular experiments of strong coupling in systems of two-dimensional materials and nanoscale electromagnetic resonators can be explained by the symmetry-breaking light-matter interaction, which leads to the formation of a localized exciton state. In a companion letter in Physical Review Research, the team analyses the quantum optical properties of the strongly-coupled system, and predicts that polariton blockade due to nonlinear exciton-exciton interactions is well within reach by use of nanoscale resonators, such as the optical cavities designed and fabricated within the NanoPhoton research center.

Phys. Rev. B 105, 085306 (2022) - Quantum theory of two-dimensional materials coupled to electromagnetic resonators (aps.org)

Phys. Rev. Research 4, L012020 (2022) - Cavity-induced exciton localization and polariton blockade in two-dimensional semiconductors coupled to an electromagnetic resonator (aps.org)


 

NanoPhoton Lecture: III-V semiconductors on silicon hybrid nanophotonics by Fabrice Raineri

Raineri’s research activity is focused on the exploration of the interactions in III-V semiconductor/silicon hybrid photonic crystal (PhC) structures and their exploitation for the achievement of smaller, smarter, faster energy-efficient optoelectronic components which will revolutionize our world, governed by information and communication technology.

His aim is to build a new panel of optoelectronic devices, ultimate in terms of power consumption as well as in speed. His goal too is to trace new paths in nonlinear and quantum optics through the use of unprecedented optical configurations enabled by the hybrid approach. More in detail, he leads his work along three research directions namely, nanolasers, nonlinear nanophotonic devices and parametric nonlinear nanophotonics. 


 

Proof of Concept Grant from the European Research Council (ERC) to demonstrate a new optical receiver for application in integrated photonics

The project, “Fano Detector”, is based on a novel idea of using a photonic Fano resonance to demodulate high-speed coherent signals in an energy-efficient way. The project builds on research results obtained in the ERC Advanced Grant “Fano Photonics”.


Measurement set-up (left) and chip (right) with coherent detector based on Fano interference.

Contacts: 
Dr. Dagmawi Alemayehu Bekele
Prof. Jesper Mørk

ERC Press Release

@european-research-council


 

NanoPhoton paper published in NanoPhotonics

Elizaveta Semenova and Shima Kadkhodazadeh had their paper published in Nanophotonincs: Droplet epitaxy symmetric InAs/InP quantum dots for quantum emission in the third telecom window: morphology, optical and electronic properties.

We provide an analytical model to explain the kinetics of pit formation and QD base shape modification. Our theoretical calculations of electronic states reveal the properties of neutral and charged excitons and biexcitons confined in such QDs, which agree with the optical investigations of individual QDs. The optical response of QDs' ensemble suggests that FSS may indeed be negligible, as reflected in the vanishing degree of linear polarization.


 

NanoPhoton members to receive grants from the Velux Foundations

We are very proud to announce that two NanoPhoton members have received generous grants from the Velux Foundations. Senior Researcher  receives DKK 6 million for his project ‘Nanolaser based on extremely confined nonradiative state (EXTREME)’. Thomas Christensen, who is currently a research scientist at Massachusetts Institute of Technology (MIT), receives DKK 8 million for his project 'Symmetry-guided discovery of topological photonics'.


 

PhD Student joins NanoPhoton

Alisha Nanwani

We are very happy that Alisha Nanwani, PhD Student, joined NanoPhoton on 15 January 2022. 

Alisha's project deals with selective epitaxy of III-V/Si nanostructures for extreme dielectric confinement of light.


 

Postdoc joins NanoPhoton

We are very glad to welcome Yury Berdnikov, Postdoc, who joined NanoPhoton on 15 January 2022.

Yury's work is in between the nanofabrication in WP 4 and optoelectronic devices in WP 2. I investigate the ways for surface states passivation aiming to improve the optical performance of the structures with EDC cavities.   


 

Postdoc joins NanoPhoton

We are very pleased to announce that Mohammad Abutoama, postdoc, joined NanoPhoton on 15 December 2021.

Mohammad's research is focused on the interaction between colloidal Nanocrystal Quantum Dots (NQDs) and EDC cavities, including theoretical modeling, design and experimental realization of the light-matter interaction in NQDs-EDC nanostructures for proposing efficient single photon sources.


 

Yi Yu's paper published in Optica

Yi had his paper "Remote excitation between quantum emitters mediated by an optical Fano resonance" published in Optica.

We demonstrate remote coupling between two site-controlled semiconductor quantum dot emitters mediated by an optical Fano resonance induced by coupling cavity modes via a continuum waveguide state. Unlike ordinary coupled modes, the Fano mode offers both a spatially extended field and a high local density of optical states at the emitters, enhancing light–matter interaction.


 

NanoPhoton at MNE 2021 in Turin, Italy

NanoPhoton was represented at the "Micro and Nano Engineering Conference” (mne2021.org) in Turin, Italy by members Søren Stobbe, Ali Nawaz Babar, Marcus Albrechtsen and Søren Engelberth Hansen, seen here with DTU colleague Christian Anker Rosiek. The team presented recent work on Casimir forces in nanostructures, photonic topological insulators, and cavities with extreme dielectric confinement.


 

Paper on "Ultra-coherent Fano laser based on a bound state in the continuum" in Nature Photonics

Graphics: DTU Fotonik. The figure shows a schematic of light generation in a Fano laser.

In a recent paper in Nature Photonics, "Ultra-coherent Fano laser based on a bound state in the continuum", we show how a bound state in the continuum can be used to reduce the spectral linewidth of microlasers significantly. The microscopic laser developed at DTU Fotonik and NanoPhoton - Center for Nanophotonics prove to have fundamental advantages compared to other lasers. Please, find the paper here.


 

NanoPhoton Lecture: Mesoscopic electrodynamics at metal surfaces: quantum and nonlocal effects by N. Asger Mortensen

Plasmonic phenomena in metals are commonly explored within the framework of classical electrodynamics and semiclassical models for the interactions of light with free-electron matter. The more detailed understanding of mesoscopic electrodynamics at metal surfaces is, however, becoming increasingly important for both fundamental developments in quantum plasmonics [1] and potential applications in emerging light-based quantum technologies [2]. While this intuitively calls for a full quantum description of plasmon-enhanced light-matter interactions, recent discoveries suggest how classical electrodynamics may still suffice if appropriately dressed by quantum-corrected mesoscopic boundary conditions – surface-response formalism. The colloquium will address three cases, where mesoscopic electrodynamic effects matter: 1) plasmon-emitter interactions [3], electronic surface states in crystalline materials [4], and plasmon-polariton interactions in graphene-on-metal structures [5]. Finally, prospects for probing electrodynamics of correlated electron materials are discussed [6]. 

References
[1] N.A. Mortensen, “Mesoscopic electrodynamics at metal surfaces – From quantum-corrected hydrodynamics to microscopic surface-response formalism”, Nanophotonics 10, 2563 (2021). [2] A.I. Fernández-Domínguez, S.I. Bozhevolnyi & N.A. Mortensen, “Plasmon-enhanced generation of non-classical light”, ACS Photonics 5, 3447 (2018). [3] P.A.D. Gonçalves et al., ”Plasmon-Emitter Interactions at the Nanoscale”, Nat. Commun. 11, 366 (2020).  [4] A.R. Echarri et al., "Optical response of noble metal nanostructures: Quantum surface effects in crystallographic facets", Optica 8, 710 (2021). [5] P.A.D. Gonçalves et al., Quantum Surface-Response of Metals Revealed by Acoustic Graphene Plasmons", Nat. Commun. 12, 3271 (2021). 
[6] A.T. Costa et al., "Harnessing Ultra-confined Graphene Plasmons to Probe the Electrodynamics of Superconductors", PNAS 118, e2012847118 (2021).


 

Tutorial papers in Top Downloads list for JOSA B

Topology optimization

We are proud to see that our tutorial papers on inverse design in photonics by topology optimization jumped to the top of the Top Downloads list for JOSA B upon publication and remain on the list ten months later.

Utilize topology optimization to design an optical metalens, a demultiplexer or a plasmonic reflector, either by the click of a button in COMSOL Multiphysics https://doi.org/10.1364/JOSAB.406048 or via a compact 200 line MATLAB code https://doi.org/10.1364/JOSAB.405955.


 

Modal Properties of Photonic Crystal Cavities and Applications to Lasers

We have reviewed the properties of the resonant modes of photonic crystal cavities with a special focus on line-defect cavities and applications to ultra-small and energy-efficient semiconductor lasers including slow-light photonic crystal lasers and Fano lasers. We have also covered emerging cavities for extreme dielectric confinement, which promise extremely strong light–matter interactions with deep sub-wavelength mode size and a high quality factor. 

You will find the paper here.


 

Official opening of NanoPhoton

We are very pleased to share some photos from the official opening ceremony of NanoPhoton - Center for Nanophotonics led by Prof. Jesper Mørk. It was a long-awaited and festive event. We extend our thanks to the Chairman of the Board of the Danmarks Grundforskningsfond/The Danish National Research Foundation, Prof. Jens Kehlet Nørskov, and the President of DTU, Prof. Anders Overgaard Bjarklev, for inspiring and supportive opening speeches. We also thank our collaborators and all of you who took the time to celebrate this wonderful occasion with us.

Rektor Anders Bjarklev og centerleder Jesper Mørk
President of DTU, Prof. Anders Overgaard Bjarklev and
  Center Leader of NanoPhoton, Prof. Jesper Mørk 

Tilhørere ved åbningen af NanoPhoton
Participants in the official opening of NanoPhoton

Jesper Mørk, Palle Jeppesen og Bjarne Tromborg
Jesper Mørk, Palle Jeppesen and Bjarne Tromborg

Maria Vittoria, Evangelos, Marco and Lotte
Members of NanoPhoton

 


 

Postdoc joins NanoPhoton

Ayman Nassar Kamel

We are pleased to announce that Ayman Nassar Kamel, Postdoc, joined NanoPhoton on 1 October.

Ayman works on the integration of EDC cavities with nano-electronic devices with a vision of providing a platform for sub-femto-joule-per-bit interconnects. He has experience in non-linear integrated optics and interface physics, both of which are useful for such nano-optoelectronic devices we hope to realize.  


 

PhD Student joins NanoPhoton

Maria Vittoria Gurrieri

We are pleased to announce that Maria Vittoria Gurrieri,
PhD Student, joined NanoPhoton on 1 October.

Maria Vittoria works on the development of theoretical
models for light-matter interaction in EDC-structures.
Her research is focused on the investigation of such
interaction in optical nanocavities coupled with 2D
materials. 


 

NanoPhoton Lecture: Single-photon quantum hardware: towards scalable photonic quantum technology with a quantum advantage by Peter Lodahl

Quantum dots embedded in photonic nanostructures offer a highly efficient and coherent deterministic photon-emitter interface [1]. It constitutes an on-demand single-photon source for quantum-information applications, enables single-photon nonlinear, optics and the constructing of deterministic quantum gates for photons [2]. We review recent experimental progress, and demonstrate that the current technology can be scaled up to reach quantum advantage [3] with the demonstration of near-transform-limited emitters in high-cooperativity planar nanophotonic waveguides [4]. The coherent control of a single spin in the quantum dot [5, 6] offers additional opportunities of generating advanced multi-photon entangled states [7]. We discuss potential applications of these novel deterministic photonic hardware in quantum computing and quantum communication [8], e.g., for constructing a resource efficient one-way quantum repeater [9].

References
[1] Lodahl et al., Rev. Mod. Phys. 87, 347 (2015). [2] Lodahl, Quantum Science and Technology 3, 013001 (2018). [3] Uppu et al., Science Advances 6, eabc8268 (2020). [4] Pedersen et al., ACS Photonics (2020). [5] Javadi et al., Nature Nanotechnology 13, 398 (2018). [6] Appel et al., Phys. Rev. Lett. 126, 013602 (2021). [7] Tiurev et al., Arxiv: 2007.09295. [8] Uppu et al., Arxiv: 2103.01110. [9] Borregaard et al., Phys. Rev. X 10, 021071 (2020).

 


 

NanoPhoton Lecture: From Photonic Crystals to Topological Nanophotonics by Masaya Notomi

 


 

NanoPhoton Lecture: Prospects and limitations of atomically thin semiconductors as laser gain material by Christopher Gies

 


 

NanoPhoton Lecture:Non-Radiating Electromagnetic Sources by Sergey I. Bozhevolnyi