Imperial College London

ProfessorRupertOulton

Faculty of Natural SciencesDepartment of Physics

Professor of Nanophotonics
 
 
 
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Contact

 

+44 (0)20 7594 7576r.oulton

 
 
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Location

 

914Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

164 results found

Besteiro LV, Cortes E, Ishii S, Narang P, Oulton RFet al., 2021, Hot electron physics and applications, JOURNAL OF APPLIED PHYSICS, Vol: 129, ISSN: 0021-8979

Journal article

Rodrigues JD, Dhar HS, Walker BT, Smith JM, Oulton RF, Mintert F, Nyman RAet al., 2021, Learning the Fuzzy Phases of Small Photonic Condensates, PHYSICAL REVIEW LETTERS, Vol: 126, ISSN: 0031-9007

Journal article

Clark AS, Chekhova M, Matthews JCF, Rarity JG, Oulton RFet al., 2021, Special Topic: Quantum sensing with correlated light sources, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951

Journal article

Dhar HS, Rodrigues JD, Walker BT, Oulton RF, Nyman RA, Mintert Fet al., 2020, Transport and localization of light inside a dye-filled microcavity, Physical Review A: Atomic, Molecular and Optical Physics, Vol: 102, Pages: 1-9, ISSN: 1050-2947

The driven-dissipative nature of light-matter interaction inside a multimode, dye-filled microcavity makes it an ideal system to study nonequilibrium phenomena, such as transport. In this work, we investigate how light is efficiently transported inside such a microcavity, mediated by incoherent absorption and emission processes. In particular, we show that there exist two distinct regimes of transport, viz. conductive and localized, arising from the complex interplay between the thermalizing effect of the dye molecules and the nonequilibrium influence of driving and loss. The propagation of light in the conductive regime occurs when several localized cavity modes undergo dynamical phase transitions to a condensed, or lasing, state. Furthermore, we observe that, while such transport is robust for weak disorder in the cavity potential, strong disorder can lead to localization of light even under good thermalizing conditions. Importantly, the exhibited transport and localization of light is a manifestation of the nonequilibrium dynamics rather than any coherent interference in the system.

Journal article

Pearce E, Phillips CC, Oulton RF, Clark ASet al., 2020, Heralded spectroscopy with a fiber photon-pair source, Applied Physics Letters, Vol: 117, Pages: 1-6, ISSN: 0003-6951

The correlations between photons generated by nonlinear optical processes offer advantages for many quantum technology applications, including spectroscopy, imaging, and metrology. Here, we use spontaneous four-wave mixing in a birefringent single-mode fiber pumped by a tunable pulsed laser as a broadly tunable source of phase-matched non-degenerate photon pairs for spectroscopy. The pairs are tunable such that the idler beam measures the transmittance spectrum of a sample in the near infrared, while the visible signal beam independently reports correlation information. By the time-resolved counting of both signal and idler photons, we use photon-number correlations to remove uncorrelated noise from the probe beam. Here, we have used heralded spectroscopy to measure the absorption spectrum of gallium arsenide near its band edge, despite the idler photon spectrum being dominated by a large background from spontaneous Raman scattering.

Journal article

Grinblat G, Zhang H, Nielsen MP, Krivitsky L, Berte R, Li Y, Tilmann B, Cortes E, Oulton RF, Kuznetsov A, Maier SAet al., 2020, Efficient ultrafast all-optical modulation in a nonlinear crystalline gallium phosphide nanodisk at the anapole excitation, SCIENCE ADVANCES, Vol: 6, ISSN: 2375-2548

Journal article

Sistani M, Bartmann MG, Gusken NA, Oulton RF, Keshmiri H, Minh AL, Momtaz ZS, Den Hertog M, Lugstein Aet al., 2020, Plasmon-Driven Hot Electron Transfer at Atomically Sharp Metal-Semiconductor Nanojunctions, ACS PHOTONICS, Vol: 7, Pages: 1642-1648, ISSN: 2330-4022

Journal article

Sistani M, Bartmann MG, Gusken NA, Oulton RF, Keshmiri H, Minh AL, Robin E, den Hertog M, Lugstein Aet al., 2020, Stimulated Raman Scattering in Ge Nanowires, JOURNAL OF PHYSICAL CHEMISTRY C, Vol: 124, Pages: 13872-13877, ISSN: 1932-7447

Journal article

Azzam SI, Kildishev AV, Ma R-M, Ning C-Z, Oulton R, Shalaev VM, Stockman MI, Xu J-L, Zhang Xet al., 2020, Ten years of spasers and plasmonic nanolasers., Light Sci Appl, Vol: 9

Ten years ago, three teams experimentally demonstrated the first spasers, or plasmonic nanolasers, after the spaser concept was first proposed theoretically in 2003. An overview of the significant progress achieved over the last 10 years is presented here, together with the original context of and motivations for this research. After a general introduction, we first summarize the fundamental properties of spasers and discuss the major motivations that led to the first demonstrations of spasers and nanolasers. This is followed by an overview of crucial technological progress, including lasing threshold reduction, dynamic modulation, room-temperature operation, electrical injection, the control and improvement of spasers, the array operation of spasers, and selected applications of single-particle spasers. Research prospects are presented in relation to several directions of development, including further miniaturization, the relationship with Bose-Einstein condensation, novel spaser-based interconnects, and other features of spasers and plasmonic lasers that have yet to be realized or challenges that are still to be overcome.

Journal article

Azzam S, Kildishev A, Ma R-M, Ning C-Z, Oulton R, Shalaev VM, Stockman M, Xu J-L, Zhang Xet al., 2020, Ten years of spasers and plasmonic nanolasers, LIGHT-SCIENCE & APPLICATIONS, Vol: 9, ISSN: 2047-7538

Journal article

Gusken NA, Nielsen MP, Nguyen NB, Shi X, DIchtl P, Oulton RFet al., 2020, Efficient Four Wave Mixing and Low-Loss Adiabatic In-Coupling in Hybrid Gap Plasmonic Waveguides, ISSN: 1092-8081

We show four-wave-mixing over 2 μm with 1% signal-to-idler conversion efficiency enabled by strong non-linearities and highly confined fields. We also demonstrate low-loss in-coupling into nanometer gaps with an efficiency of 80%.

Conference paper

Doiron B, Gusken NA, Lauri A, Li Y, Mihai A, Matsui T, Bower R, Huettenhoffer L, Regoutz A, Forno SD, Fearn S, Petrov PK, Cortes E, Cohen LF, Alford NM, Lischner J, Petrov P, Maier SA, Oulton RFet al., 2020, Hot Carrier Optoelectronics with Titanium Nitride, Lasers and Electro-Optics Society Annual Meeting-LEOS, ISSN: 1092-8081

© 2020 OSA. Titanium oxynitride enables a range of plasmonic and optoelectronic functionality using long-lived photo-generated hot carriers. We explore the time scale of hot carriers in TiN and their use in photochemical reduction and Schottky detectors.

Conference paper

Marques Rodrigues J, Walker BT, Dhar HS, Oulton R, Mintert F, Nyman RAet al., 2020, Non-stationary statistics and formation jitter in transient photon condensation, Nature Communications, Vol: 11, ISSN: 2041-1723

While equilibrium phase transitions are easily described by order parameters and free-energylandscapes, for their non-stationary counterparts these quantities are usually ill-defined. Here,we probe transient non-equilibrium dynamics of an optically pumped, dye-filled microcavity. Wequench the system to a far-from-equilibrium state and find delayed condensation close to a criticalexcitation energy, a transient equivalent of critical slowing down. Besides number fluctuations nearthe critical excitation energy, we show that transient phase transitions exhibit timing jitter in thecondensate formation. This jitter is a manifestation of the randomness associated with spontaneousemission, showing that condensation is a stochastic, rather than deterministic process. Despite thenon-equilibrium character of this phase transition, we construct an effective free-energy landscapethat describes the formation jitter and allows, in principle, its generalization to a wider class ofprocesses.

Journal article

Walker BT, Rodrigues JD, Dhar HS, Oulton RF, Mintert F, Nyman RAet al., 2020, Non-stationary statistics and formation jitter in transient photon condensation, Publisher: NATURE PUBLISHING GROUP

Working paper

Gusken NA, Nielsen MP, Nguyen NB, Shi X, Dichtl P, Oulton RFet al., 2020, Efficient four wave mixing and low-loss adiabatic in-coupling in hybrid gap plasmonic waveguides, Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020

Conference paper

Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2020, Mixed order nonlinear processes from metasurfaces of multi-resonant gold antennas, Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020

Conference paper

Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2020, Nonlinear Geometric Phase Gradient Metasurface beyond the Dipole Approximation, Conference on Lasers and Electro-Optics (CLEO), Publisher: IEEE, ISSN: 2160-9020

Conference paper

Güsken NA, Nielsen MP, Nguyen NB, Shi X, Dichtl P, Oulton RFet al., 2020, Efficient four wave mixing and low-loss adiabatic in-coupling in hybrid gap plasmonic waveguides

We show four-wave-mixing over 2 µm with 1% signal-to-idler conversion efficiency enabled by strong non-linearities and highly confined fields. We also demonstrate low-loss in-coupling into nanometer gaps with an efficiency of 80%.

Conference paper

Doiron B, Güsken NA, Lauri A, Li Y, Mihai A, Matsui T, Bower R, Huettenhoffer L, Regoutz A, Forno SD, Fearn S, Petrov PK, Cortés E, Cohen LF, Alford NM, Lischner J, Petrov P, Maier SA, Oulton RFet al., 2020, Hot carrier optoelectronics with titanium nitride

Titanium oxynitride enables a range of plasmonic and optoelectronic functionality using long-lived photo-generated hot carriers. We explore the time scale of hot carriers in TiN and their use in photochemical reduction and Schottky detectors.

Conference paper

Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2020, Mixed order nonlinear processes from metasurfaces of multi-resonant gold antennas

We demonstrate mixed-order nonlinear frequency mixing in Au antennas and reveal the role of high order antenna modes in Pancharatnam-Berry Phase metasurfaces. The application of ultrafast pulse characterization is explored.

Conference paper

Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2020, Nonlinear geometric phase gradient metasurfaces beyond the dipole approximation

In this work, we identify the role of higher order antenna’s modes on a metasurface’s Pancharatnam – Berry phase by investigating second harmonic light scattering from two metasurfaces exhibiting dipolar and quadrupolar radiation.

Conference paper

Gusken NA, Lauri A, Li Y, Jacassi A, Matsui T, Doiron B, Bower R, Regoutz A, Mihai A, Petrov PK, Oulton RF, Cohen LF, Maier SAet al., 2020, IR hot carrier based photodetection in titanium nitride oxide thin film-Si junctions, MRS Advances, Vol: 5, Pages: 1843-1850, ISSN: 2059-8521

Hot carrier based methods constitute a valuable approach for efficient and silicon compatible sub-bandgap photodetection. Although, hot electron excitation and transfer have been studied extensively on traditional materials such as Au and Ti, reports on alternative materials such as titanium nitride (TiN) are rare. Here, we perform hot hole photodetection measurements on a p-Si/metal thin film junction using Ti, Au and TiN. This material is of interest as it constitutes a refractory alternative to Au which is an important property for plasmonic applications where high field intensities can occur. In contrast to Au, a TiN/Si junction does not suffer from metal diffusion into the Si, which eases the integration with current Si-fabrication techniques. This work shows that a backside illuminated p-Si/TiN system can be used for efficient hot hole extraction in the IR, allowing for a responsivity of 1 mA/W at an excitation wavelength of 1250 nm and at zero bias. Via a comparison between TiN and other commonly used materials such as Au, the origin of this comparably high photoresponse can be traced back to be directly linked to a thin TiO2-x interfacial layer allowing for a distinct hot-hole transfer mechanism. Moreover, the fabrication of TiN nanodisk arrays is demonstrated which bears great promise to further boost the device efficiency.

Journal article

Sistani M, Bartmann MG, Gusken NA, Oulton RF, Keshmiri H, Seifner MS, Barth S, Fukata N, Luong MA, den Hertog MI, Lugstein Aet al., 2019, Nanoscale aluminum plasmonic waveguide with monolithically integrated germanium detector, Applied Physics Letters, Vol: 115, Pages: 161107-1-161107-4, ISSN: 0003-6951

Surface plasmon polaritons have rapidly established themselves as a promising concept for molecular sensing, near-field nanoimaging, andtransmission lines for emerging integrated ultracompact photonic circuits. In this letter, we demonstrate a highly compact surface plasmonpolariton detector based on an axial metal-semiconductor-metal nanowire heterostructure device. Here, an in-coupled surface plasmonpolariton propagates along an aluminum nanowire waveguide joined to a high index germanium segment, which effectively acts as a photoconductor at low bias. Based on this system, we experimentally verify surface plasmon propagation along monocrystalline Al nanowires asthin as 40 nm in diameters. Furthermore, the monolithic integration of plasmon generation, guiding, and detection enables us to examine thebending losses of kinked waveguides. These systematic investigations of ultrathin monocrystalline Al nanowires represent a general platformfor the evaluation of nanoscale metal based waveguides for transmission lines of next generation high-speed ultracompact on-chip photoniccircuits.

Journal article

Dichtl P, Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2019, Exploiting the nonlinear optical response of gold nanoantennas for ultrafast pulse characterisation

Two femtosecond laser pulses in the near-infrared and near the edge of the visible waveband are characterized simultaneously by a time-resolved analysis of nonlinear scattering from gold nanoparticles.

Conference paper

Dichtl P, Abdelwahab I, Grinblat G, Leng K, Chi X, Park IH, Nielsen MP, Oulton RF, Loh KP, Maier SAet al., 2019, Giant and tunable optical nonlinearity in single-crystalline 2D perovskites due to excitonic and plasma effects

2D Ruddlesden-Popper-type lead halide perovskites exhibit a strong third-order nonlinear response around excitonic resonance, which is characterized with Z-scan measurements. We find large absolute values and a sign change of both nonlinear refraction and absorption.

Conference paper

Gennaro SD, Li Y, Maier SA, Oulton RFet al., 2019, Nonlinear Pancharatnam-Berry Phase Metasurfaces beyond the Dipole Approximation, ACS PHOTONICS, Vol: 6, Pages: 2335-2341, ISSN: 2330-4022

Journal article

Grandi S, Nielsen MP, Cambiasso J, Boissier S, Major K, Reardon C, Krauss TF, Oulton R, Hinds E, Clark Aet al., 2019, Hybrid plasmonic waveguide coupling of photons from a single molecule, APL Photonics, Vol: 4, Pages: 086101-1-086101-6, ISSN: 2378-0967

We demonstrate the emission of photons from a single molecule into a hybrid gap plasmon waveguide (HGPW). Crystals of anthracene, doped with dibenzoterrylene (DBT), are grown on top of the waveguides. We investigate a single DBT molecule coupled to the plasmonic region of one of the guides, and determine its in-plane orientation, excited state lifetime and saturation intensity. The molecule emits light into the guide, which is remotely out-coupled by a grating. The second-order autocorrelation and cross-correlation functions show that the emitter is a single molecule and that the light emerging from the grating comes from that molecule. The couplinge fficiency is found to be βWG = 11.6(1:5)%. This type of structure is promising for building new functionality into quantum-photonic circuits, where localised regions of strong emitter-guide coupling can be interconnected by low-loss dielectric guides.

Journal article

Doiron B, Li Y, Mihai A, Bower R, Alford NM, Petrov PK, Maier SA, Oulton RFet al., 2019, Plasmon-enhanced electron harvesting in robust titanium nitride nanostructures, The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces, Vol: 123, Pages: 18521-18527, ISSN: 1932-7447

Titanium nitride (TiN) continues to prove itself as an inexpensive, robust, and efficient alternative to gold in plasmonic applications. Notably, TiN has improved hot electron-harvesting and photocatalytic abilities compared to gold systems, which we recently attributed to the role of oxygen in TiN and its native semiconducting TiO2–x surface layer. Here, we explore the role of localized surface plasmon resonances (LSPRs) on electron harvesting across the TiN/TiO2–x interface and probe the resilience of TiN nanostructures under high-power laser illumination. To investigate this, we fabricate TiN strips, in which the lateral confinement allows for the polarization-selective excitation of the LSPR. Using ultrafast pump–probe spectroscopy, optical characterization, and Raman vibrational spectroscopy, we relate the differences and changes observed in the electron behavior to specific material properties. We observe plasmon-enhanced electron harvesting beyond what is expected resulting from the enhanced absorption of the plasmonic mode. We accredit this to the surface oxide damping the plasmon resonance, providing additional nonradiative loss channels. Subsequently, we show that low-power annealing of the surface oxide layer reduces the trap density at the interface and increases the initial harvested electron concentration. The unique properties of TiN make it important in the future development of plasmonic electron-harvesting applications.

Journal article

Grinblat G, Abdelwahab I, Nielsen MP, Dichtl P, Leng K, Oulton RF, Loh KP, Maier SAet al., 2019, Ultrafast All-Optical Modulation in 2D Hybrid Perovskites, ACS NANO, Vol: 13, Pages: 9504-9510, ISSN: 1936-0851

Journal article

Abdelwahab I, Dichtl P, Grinblat G, Leng K, Chi X, Park I-H, Nielsen MP, Oulton RF, Loh KP, Maier SAet al., 2019, Giant and Tunable Optical Nonlinearity in Single-Crystalline 2D Perovskites due to Excitonic and Plasma Effects, ADVANCED MATERIALS, Vol: 31, ISSN: 0935-9648

Journal article

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