Max Planck-uOttawa Centre for Extreme and Quantum Photonics: Projects

Development of nonlinear optical materials and structures

Nonlinear optical interactions form the underlying mechanism for much current work in practical photonics and for most implementations of photon-based quantum information science.  These applications will perform only as well as permitted by the photonic materials being used.  Thus it is crucial to develop the best possible nonlinear optical materials and structures.  We will approach this problem from several different perspectives.  (a) We will develop nanocomposite materials for use in photonics.  The early work by Boyd showed that nanocomposite materials can possess nonlinear coefficients larger than those of the materials from which they are formed.  We will pursue this line of work.  (b) We will study materials (such as ITO) and structures (even as simple as that of a layered composite) for which the dielectric constant is very small; such materials are often referred to as epsilon-near-zero (ENZ) materials.  The importance of ENZ materials is that the relation between n(2) and chi(3) depends on the value of epsilon, and from this point of view one expects n(2) to be very large in an ENZ material.  (c) We will also work on the development of materials with a large nonlinearity as the result of surface structuring. Structuring of a surface leads to the strong local concentration of electric field strength of any incident light beam, leading to a large nonlinear optical response. (Boyd, Leuchs, Berini, Russell) (d) We will exploit the intrinsic nonlinearity of quantum emitters such as atoms and molecules to explore nonlinear optics with few photons. Here, a key advantage will be the recent demonstration by the groups of Sandoghdar and Leuchs that high-efficiency coupling between atoms and photons can be achieved using tight focusing or optical antennas.

Maybe drop Lead Researchers from all topics. But I will let Gerd decide Lead researchers: Sandoghdar, Leuchs, and Boyd

Fabrication of photonic crystals (PhCs) possessing almost limitless uses in photonics applications

A PhC is a structure in which the refractive index is modulated on a distance scale of the order of half the effective optical wavelength. The index modulation is often achieved by etching a periodic array of holes in the host material.  Because of the index modulation, PhCs possess a stop band, that is, a range of frequencies for which light cannot propagate.  However, defects in a PhC can lead to dramatic optical effects.  If one or several adjacent holes are omitted from the structure, this region can serve as an optical resonator with a Q as large as 106.  If a line of holes is removed, this region can serve as an optical waveguide, with the crucial property that the bend radius can be very small, on the order of one micron, very much unlike the properties of an optical fibre. While Yablonovich pioneered using PhCs to confine light, Russell is the pioneer in using PhCs to guide light. PhCs can be used to fabricate many types of photonic structures, as is described in our other projects.

Lead researchers: Russell and Boyd

Slow light for photonics

Many of the materials and structures we describe in these projects possess strong dispersion (that is, a variation of refractive index with wavelength). Highly dispersive materials display a “slow light” effect, that is, the group velocity of light can be much smaller that the velocity of light in vacuum. This property can be used to create novel photonic devices, such as chip-scale switchable optical delay lines, which could have important implications in telecommunications. While early work on slow light was focused on the response of free atoms, the development of slow light methods in room temperature solids was pioneered by Boyd. One specific aspect of this research is to construct miniaturized chip-scale spectrometers in which the spectral resolution is enhanced by the use of slow-light methods.  

Lead researchers: Boyd, Russell, and Dolgaleva

Development of PhC fibres

These are optical fibres in which the transverse cross section consists of longitudinal holes in the optical fibre, which serve to guide light in the central region, which is often hollow. Russell invented the PhC fibre.  Part of our research will entail filling the holes of such a fibre with various nonlinear optical materials.  Such a system is expected to show extremely strong nonlinear optical effects, both because of the long propagation distances permitted by an optical fibre and because of the strong confinement of the electric field within the fibre.

Lead researchers: Russell, Leuchs, Marquardt, and Boyd

Applications of photonic nanostructures

Certain photonic nanostructures have important implications for the field of photonics.  Broadly speaking, these nanostructures will be optimized to enhance light-matter interactions for applications such as optical switching, biosensing, quantum information science, and efficient solar energy conversion. For instance, Berini investigated and demonstrated amplifiers, oscillators (lasers) and photodetectors operating with surface plasmons. The goal is to exploit the unique features of photonic nanostructures so as to improve the performance.  We will target applications in low-noise amplifiers, low-cost broadly tuneable lasers, nano-particle lasers, and sub-bandgap photodetectors. We are also working on nano-structures for the optical generation of THz waves through difference-frequency generation, targeting sensing and secure short-range communications.

Lead researchers: Boyd, Leuchs, and Berini

Imaging with a single photon

This work seeks to answer: “How much information can be encoded onto a single photon.”  One prototypical experiment performed by Boyd involves encoding one of a predetermined collection of images onto a single photon.  This photon then falls onto multiplexed hologram and is diffracted into different directions depending on which image is encoded on the photon.  Our work will entail making such protocols more robust and decreasing the amount of crosstalk among the images.  Applications include surveillance at minimum illumination levels and the secure transfer of image information. This topic is intimately related to that of Quantum Key Distribution in which many bits of information are encoded on each photon.

Lead researchers: Boyd and Leuchs

Extreme UV laser physics

The field of attoscience was pioneered by Krausz and Corkum. We will continue our development of new methods in high-intensity physics and the generation of attosecond pulses. We will also explore the use of these attosecond methods for the ultrafast characterization of materials.

Lead researchers: Russell, Krausz, Corkum, and Boyd

Gas-filled hollow-core PhC fibres

Gas-filled hollow-core photonic-crystal fibre for extreme pulse compression, generation of deep and vacuum UV light, and ionization-driven dynamics including high harmonic generation and mass spectrometry ­ all at low (few-µJ) infrared pulse energies. One of Russell's specialities, which he pioneered, is the control of light propagation by spatially modulating parameters of the fibre through which it propagates. This provides a novel technique for confining a desired medium such as an inert gas inside the hollow core of a glass fibre using photonic crystal guiding with custom engineered mode structures. The goal is combining this with high-harmonic generation, which can be used to produce ultra-short light pulses in the attosecond regime, an area led by Corkum and Krausz. High- harmonic generation in noble gases confined in a single mode of a hollow photonic crystal fibre would be a major and most promising step in striving for improved performance regarding higher efficiency and shorter pulses.

Lead researchers: Russell, Corkum, and Krausz

Ultrafast optics and high-harmonic generation (HHG) excited by structured laser beams

We want to study HHG with structured laser beams, for instance, beams that carry orbital angular momentum (OAM). Studies of this sort will allow for a more detailed analysis of the dynamics of the HHG process and may open new pathways for imaging with nano-scale spatial resolution. This task is an extension of point our project on Extreme UV Laser Physics, but concentrates on studying the interaction with high-order modes of the pump field. Boyd will provide his know-how on orbital angular momentum (OAM) modes and Leuchs will contribute regarding the generation and handling of more general cylindrical vector modes. Together with Corkum, Krausz and Russell, all four will team up to investigate HHG, using these higher order modes in the bulk and in photonic crystal fibres.

Lead researchers: Corkum, Russell, Boyd, and Leuchs

Development of a free-space quantum key distribution (QKD) that can transmit many bits of information per photon

Such a system could increase dramatically the transmission rates of QKD systems. Our implementation based on earlier work by Boyd will encode information using light beams that carry orbital angular momentum (OAM), such as the Laguerre-Gauss modes.  There are an infinite number of Laguerre-Gauss modes, and thus in principle there is no limit to how many bits of information can be carried by a single photon.  The Leuchs group is operating a free-space QKD transmission line at Erlangen, and Boyd has developed a laboratory system that can carry more than one bit of information per photon. These two groups will work jointly to study the utility of using, OAM states for QKD.

Lead researchers: Leuchs, Boyd, and Marquardt

Nonlinear optics with intense quantum states of light

The Leuchs group has developed techniques that allow them to generate intense beam of light that display strong quantum features such as squeezing.  Theoretical work has shown that beams of this sort exhibit unusual statistical properties that can lead to extremely strong nonlinear optical interactions and which have not been previously observed experimentally.  Moreover, light beams of this sort hold great promise for applications such as high-precision metrology. More broadly, this work will allow us to study fundamental properties of light-matter interactions and could lead to new applications of quantum nonlinear optics.

Lead researchers: Boyd, Leuchs, and Chekhova

Development of whispering gallery mode (WGM) resonators for quantum photonics

The Leuchs group has been working on the development of WGM resonators for use in photonics. This work is closely related to earlier work by Boyd on nonlinear WGM resonators and by Leuchs on nonlinear monolithic resonators. The large build-up of intensity within such a resonator leads to a large enhancement of its nonlinear optical characteristics. As part of this task, we will make use of the properties of WGM resonators to produce THz radiation and to produce entangled photon pairs for use in experiments in quantum optics and quantum information science.

Lead researchers: Leuchs and Boyd

Development of plasmonic nano-antennas, arrays of nano-antennas, and other structured surfaces

Plasmonic nano-antennas hold great promise for increasing the electric field strength locally as demonstrated by earlier work of Berini.  We will extend this earlier work by constructing single-photon sources. Arrays of nano-antennas are of importance both for fundamental studies and for applications. At the fundamental level, we are interested in studying the properties of superradiance in an array of nano-antennas.  At the practical level, Boyd has recently shown that a properly constructed array of nano-antennas can convert a beam carrying circular polarization to a beam carrying orbital angular momentum (OAM).  This ability is crucial in the design of quantum information systems in which part of the logic is performed using the polarization state and part is performed using the OAM state.  We are also interested in the study of structured surfaces, especially those with a chiral structure. Applications of such structures include the development of chemical species- and chirality-selective chemical detectors, and nonlinear devices enhanced by the process of surface structuring.

Lead researchers: Russell, Leuchs, Boyd, and Berini

Development of optical interactions and methods based on the use of “structured light”

The further development of electron Bessel beams and their use in the construction of improved electron microscopes.  Boyd along with Italian collaborators has recently shown that it is possible to create a hologram for electrons that can render a collimated electron beam into a beam with a Bessel function cross section.  Such a beam has a central lobe that is more tightly confined than a Gaussian beam and moreover has a larger longitudinal extent of the focal region.  The next step in this project is to place such a hologram into an electron microscope and demonstrate that this procedure can produce enhanced resolution. 

Lead researchers: Boyd, Corkum, and Leuchs

Advanced development of electron Bessel beams and their use in the construction of improved electron microscopes

The further development of electron Bessel beams and their use in the construction of improved electron microscopes.  Boyd along with Italian collaborators has recently shown that it is possible to create a hologram for electrons that can render a collimated electron beam into a beam with a Bessel function cross section.  Such a beam has a central lobe that is more tightly confined than a Gaussian beam and moreover has a larger longitudinal extent of the focal region.  The next step in this project is to place such a hologram into an electron microscope and demonstrate that this procedure can produce enhanced resolution. 

Lead researchers: Boyd, Corkum, and Leuchs

Quantum nonlinear optics of atomic vapours, trapped ions, and isolated molecules

Atoms and molecules play a special role in optical physics.  Historically, it was the study of atomic systems and the realization that they possess discrete resonances that helped create the discipline of quantum mechanics.  From a different point of view, atomic and molecular systems are useful for fundamental and practical studies because they possess sharp resonance lines that can enhance their nonlinear optical response.  Our work in this area includes the following topics:  (a) How are the properties of a beam carrying orbital angular momentum modified when it propagates through an atomic vapour?  (b) How is the process of photon drag modified when a laser is tuned close to a resonance line, thereby inducing a large amount of linear dispersion into the system? (c) How are optical levitation and optical trapping modified when the background medium is a highly dispersive atomic vapour?  (d) How efficiently can a single molecule reflect laser light? (e) Can one demonstrate the time reversal of the exponential decay in spontaneous emission of a single trapped ion?

Lead researchers: Leuchs, Sandoghdar, and Boyd

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