[NAP Poster 1] Plasmonic and Photonic Nanostructures for Single Photon Source Application
Oscar Ta and Svetlana G Lukishova
Secure quantum communication requires fluorescent single-emitter sources. Current research efforts seek to fabricate single-emitters for single-photon generation at room temperature. The primary sample studied was an array of silver nanorods atop a photoalignment polymer layer and gold layer. A confocal microscope, coupled with a spectrometer and Hanbury Brown-Twiss correlator, was used to characterize samples for single-emitter fluorescence, photon statistics, and spectral intensity. Results show photon antibunching and fluorescence enhancement in the primary sample. By using a finite-difference time domain (FDTD) method, an optical simulation package developed by Lumerical was used to analyze the optical cross-section of each layer, as well as the entire sample. As understood through simulations, aggregations of nanorods tend to shift the resonant wavelength towards the UV region while increasing the scattering cross-section.
Additionally, index variation in the photoalignment polymer was shown to change linearly with the resonant wavelength.
[NAP Poster 2] (Withdrawn) Design and analysis of NAND gate in photonic crystals
Brahm Raj Singh, Ishan Joshi, Kuvam Uppal and Swati Rawal
[NAP Poster 3] (Withdrawn) Strong Coupling Between Plasmonic and Molecular Vibrational Resonances in the Mid Infrared Range
K. Menghrajani, G. Nash and W.L. Barnes
[QUT Poster 1] Photon pairs from spontaneous four-wave mixing with group-velocity dispersion
Jacob G. Koefoed, Jesper B. Christensen, Colin J. McKinstrie, and Karsten Rottwitt
We model photon-pair generation under the influence of group-velocity dispersion and show that it imposes an upper limit on the heralded single-photon purity.
[QUT Poster 2] Contrast Enhanced Imaging Using Quantum Correlations
T. Gregory, P.-A. Moreau, E. Toninelli, and M.J. Padgett
Using quantum states of light as opposed to classical states allows entanglement to be exploited, thereby enabling enhancements in a number of image properties to be achieved. A contrast enhancement is achieved using spatially separated signal and idler beams, one of which interacts with an object in the far-field of the entangled photon pair source and then performing a simple AND operation on the regions containing the beams. By this method an enhancement in the contrast of an image constructed using correlated light compared to that constructed from a simple average an enhancement of 1.28(6) is observed.
[NLO Poster 1] Towards Efficient Mid-Infrared Nonlinear Signal Processing Using Amorphous Silicon
Alvin Tak Lok Hui, Peter David Girouard, Abebe Tilahun Tarekegne, Yunhong Ding, Hao Hu, Lars Hagedorn Frandsen and Michael Galili
We present the fundamental studies of the dependence of mobility gap energy on deuterium passivation of amorphous silicon films. We demonstrate that the mobility gap increases with increased deuterium incorporation and that a large mobility gap of 1.57 eV is attainable while keeping the surface roughness below 1 nm rms. The finding reveals two-photon absorption is extinguished at a shorter wavelength leading to efficient on-chip nonlinear optical signal processing at mid- infrared wavelengths.
[NLO Poster 2] Mid-Infrared Upconversion imaging and spectroscopy using short pulse light sources
Ashik A S , Peter-Tidemand Lichtenberg and Christian Pedersen
The mid-infrared (mid-IR) wavelength range is an emerging and important new topic for frontier research. Its general importance relates to a multitude of mid-IR industrial and biomedical sensor applications. Chemical finger prints of most complex molecules such as those found in food, tissue or catalytic compounds all have their vibrational spectra in the mid-IR, thus identifiable through mid-IR spectroscopy. The main idea is not to develop a new IR camera, but toconvert IR signals into the near infrared, subsequently detected using existing NIR CCD or InGaAs cameras. Various upconversion methods will be explored for the detection of short (femto- picosecond) pulses. Using a tunable short pulse (ps / fs) mid-IR light source for excitation or probing of the sample and synchronizing with the residual pump light will allow the demonstration of ultra-fast upconversion imaging in the fs / ps regime as an enabling mid-IR technology. Considerable attention will be paid to increase the spatial and spectral resolution of the up-conversion process, which will lead us in the research of new non-linear crystals. Furthermore, a theoretical study of the upconversion process of very short pulses is needed in order to optimize performance.
[NLO Poster 3] A femtosecond optical synthesizer for attosecond science
B. M. R. Weaver, E. W. Larsen, D. J. Walke, D. Greening, J. P. Marangos and J. W. G. Tisch
We present work towards a femtosecond optical synthesizer for producing isolated attosecond pulses in the extreme ultraviolet. Simulations have shown that the sub-cycle shaping of waveforms for driving high harmonic generation can optimize the photon flux and maximise the photon energy of isolated attosecond pulses. We aim to achieve this by coherently combining infrared, ultraviolet and broadband visible pulses. The individual phases and amplitudes of each of the pulses are controlled to allow the sub-cycle shaping of the waveform.
[NLO Poster 4] EFFICIENT MID-IR SUPERCONTINUUM GENERATION IN QUADRATIC NONLINEAR WAVEGUIDES
G.Li, B.Zhou and M. Bache
Efficient middle infrared supercontinuum generation has been realized by cascaded nonlinearities in quadratic nonlinear crystals. By counterbalancing the cascaded nonlinear phase shift with normal dispersion, self-defocusing solitons can be generated in many standard crystals in near infrared or middle infrared. According to previous numerical simulations and experimental results, those de-focusing solitons, which can counterbalance catastrophic Kerr self/focusing effects, break the soliton limit of pump power in few μJ, supporting higher order solitons, providing a potential solution to achieve robust supercontinuum generation. The resonance radiation induced by defocusing solitons naturally goes to longer wavelength, providing the potential for a very broad (few octaves) coherent supercontinuum . In waveguides, the pump power requirements are reduced to the nJ level [3,4]. Waveguide dispersion and phase mismatch control can be used to tailor the supercontinuum content, which can also find their applications in ultra wideband telecommunications .
[NLO Poster 5] Ultra‐low Noise Supercontinuum Generation with Flat‐near Zero All Normal Dispersion Pure Silica Fiber at GHz Repetition Rate
Shreesha Rao. D. S, Rasmus D. Engelsholm, Ivan B. Gonzalo, Binbin Zhou, Patrick Bowen, Peter M. Moselund, Ole Bang and Morten Bache
A pure silica holey fiber with β2 of 0.44 ps2/ km at 1.55 μm and less than 1 ps2/ km from 1.3 to 1.75 μm was engineered and drawn. It is numerically shown to generate a flat coherent spectrum, pumped by a 2 kW peak power, 250 fs pulse propagating 20 m.
Fiber Optics and Optical Communication
[FOC Poster 1] (Withdrawn) Resilience And Reliability Analysises Of A 5 Km Free Space Optical Link Under Sand Storm And Heavy Rain
Cheikh A. B. Dath, , Aliou Niane, Modou Mbaye, and Ndèye Arame Boye Faye
[FOC Poster 2] Light Emitting Diodes and Lasers for High-Speed Underwater Optical Communications
Georgios N. Arvanitakis, Jonathan J. D. McKendry, Henry T. Bookey, Erdan Gu, and Martin D. Dawson
Underwater Optical Wireless Communications (UWOC) are of great interest for military, industrial, and scientific applications . The employment of lasers and GaN-based LEDs, enable transmission of data up to Gb/s for mid-ranged distances (<100m). We report here the employment of Corning® Fibrance® Light Diffusing Fiber  as an omnidirectional beacon- transmitter in a water tank of dimensions 1.5m×0.35m×0.35m. The beacon was coupled with an off-the-shelf Osram Green Laser Diode operated at 520nm. The transmittance of 5Mb/s was achieved through different types of sea water over a distance of 1.66m (1.55m through water). Further computational calculations showed that the distance between transmitter-receiver could be extended up to 10m for clear ocean waters.
[FOC Poster 3] All-fiber Gas-filled Hollow-Core Photonic Crystal Fibers for Gas sensing and nonlinear optics
Abubakar I. Adamu, Ole Bang and Christos Markos
Hollow-Core Photonic Crystal Fibers (HC-PCF) are being extensively studied recently, especially in the field of gas sensing and nonlinear optics . Like other optical fibers, HC-PCF confines and propagates -electromagnetic waves. Optical Fibers propagates light using the mechanism of total internal reflection; where two materials of contrasting refractive index reflect lights of specific wavelengths whose angle of incident falls below the critical angle. In HC-PCF, optical fibers (PBG-MOFs), where the refractive index of the core (air) is lower than the effective index of the cladding; guiding is achieved by the formation of a Photonic Band Gap (PBG), which prevents light from propagating in the periodic cladding, within a certain range of frequencies. In the latter case the fiber core could be hollow (air-core) – which is a necessary configuration for this project. In a HC-PCF, light propagates through the hollow-air by the photonic band gap effects, which occurs due to the periodic distribution of air holes in the cladding. The presence of little holes around the core provides a refractive index contrast in two dimensions along the fiber length. The propagation of light in air gives the possibilities for spectroscopic and gas sensing applications. We present here, the schematic for detection of Ammonia gas with a HC-PCF (HC19-1550, NKT Photonics).
[FOC Poster 4] Chip – to – chip mode-division multiplexing
Jan M. Baumann, Edson Porto da Silva, Yunhong Ding, Valerija Kamchevska, Michael Galili, Kjeld Dalgaard, Lars H. Frandsen, Leif Katsuo Oxenløwe, Toshio Morioka
A chip-to-chip mode-division multiplexing connection is demonstrated using a pair of multiplexers/demultiplexers fabricated on the silicon-on-insulator platform. Successful mode multiplexing and demultiplexing is experimentally demonstrated, using the LP01, LP11a and LP11b modes transmitting 3 x 32 Gbit/s.
[BOM Poster 1] Spectrally resolved Multiphoton Microscopy for the classification of Bladder Cancer
Björn-Ole Meyer, Dominik Marti and Peter E. Andersen
Bladder Cancer has a high impact on the society and healthcare systems. Due to its high reoccurrence and elaborate treatment methods, it has a strong financial footprint and comes with a high mortality rate as well as significant patient suffering. Although most cancerous lesions in the human bladder originate from easily accessible superficial layers, no non-invasive Technology has been presented that can match the sensitivity and specificity of stained biopsies in Histopathology. In an effort to evaluate the requirements for in-vivo diagnosis, we are seeking to define biomarkers on biopsies using a multimodal microscope. In this microscope, we will combine Multiphoton Microscopy with Optical Coherence Microscopy. Here we present a spectrally resolved Multiphoton Microscope and discuss its advantages and disadvantages for the diagnosis of Bladder Cancer. The ability to investigate spectral components of the obtained signal separately allows for differentiation between different biological structural and functional findings. With a decreased sensitivity, the imaging speed reduced, thus limiting the use of the setup only to ex-vivo investigations. This technology is the first step to a system with the abilities to investigate the prerequisites needed the development of non-invasive endoscopes for early stage cancer screening.
[BOM Poster 2] Lightguiding in III-V nanowires for biosensing applications
Damiano Verardo, Frida W. Lindberg, Nicklas Anttu, Cassandra S. Niman, Mercy Lard, Aleksandra P. Dabkovska, Tommy Nylander, Christelle Prinz and Heiner Linke
Semiconductor nanowires have shown potential in different applications, from solar cells to LEDs. In addition, their high surface area and aspect ratio makes them a good platform for studying interaction with biological molecules. Wave-guiding properties of NWs 1 might further enhance their potential for biosensing: in recent studies, we observed that light emitted by fluorophores located close to the NW surface can be coupled to the wire and emitted from the tip. 2 This has the potential to enhance the S/N ratio as the wire effectively acts as a signal integrator. In addition, individual NWs can be easily resolved optically, making each wire an extremely small sensor. 3 Here, we explore for which parameters this effect is present and its dependence on partially confined waveguide modes using confocal microscopy and FDTD modelling.
[BOM Poster 3] Optimization of Motion Correction in Dynamic PET Molecular Imaging Studies
Imaiyan Chitra Ragupathy and Sidra Rafique
The current study deals with various motion correction (MC) techniques, on dynamic PET data consisting of 3D image acquisitions over time (frames) of the serotonin reuptake system. Three dynamic PET datasets were analyzed, with 1) no movement, 2) minor movements, and 3) major movements were observed, particularly in the late frames of the PET data acquisition. Here, we optimize the threshold and filter value to minimize the cost function by using average reference frame.
[BOM Poster 4] Towards Screening of Brain Malformations with Circularly Polarized Light
Mariia Borovkova, Alexander Bykov, Alexey Popov, Jens Pahnke, and Igor Meglinski
Circularly polarized light can be utilized for the non-invasive screening of brain malformations. We demonstrate that the presence of amyloid plaques associated with the Alzheimer’s disease could be detected inside brain tissue using circularly polarized light.
[BOM Poster 5] Two-Photon Selective Plane Illumination Microscopy through Fibres (T-SPIF) – Objectives and Plans
Madhu Veettikazhy, Anders Kragh Hansen, Dominik Marti, Peter E. Andersen
For many human diseases, early diagnosis is crucial for a positive therapy outcome, but would require techniques for fast microscopic imaging of tissues inside the body at a resolution level of individual cells. One promising idea on how to accomplish this is to combine three existing techniques: (1) Two-photon microscopy provides a high imaging resolution at large depths, allowing individual cells to be imaged, (2) Selective Plane Illumination allows fast 3D image formation because an entire plane of tissue can be imaged at a time, and (3) delivering the light through fibres enables integration into endoscopes, which in turn enables access to many hollow organs inside the human body. This ambitious PhD project, (T-SPIF), aims to accomplish this challenging combination of techniques.
[BOM Poster 6] Quantum Control and Multi-Dimensional Laser-Induced Mass Spectrometry of Biomolecules
Ruth Ayers, Taran Driver, Vitali Averbukh, Jon P Marangos, Leszek J Frasinski, and Marina Edelson-Averbukh
The recently developed new two-dimensional mass spectrometry (2DMS) was applied to the analysis of short chain nucleic acids for the first time, and achieved a higher rate of fragment identification – with collision induced dissociation (CID) as the activation method – than conventional one-dimensional mass spectrometry (MS). We discuss the still higher potential of 2DMS to maximise the amount of structural information derived from MS experiments where the molecules are fragmented using ultra-short laser pulses; which typically produce spectra that are difficult to interpret. We aim to use shaped pulses to initiate laser-induced dissociation, along with 2DMS and a learning algorithm, to achieve closed loop quantum control over the dissociation of specific bonds in the biomolecules under investigation.
Attosecond Science and Optical Techniques
[OIM Poster 1] Numerical Validation of Optically Probed Species and Properties in Combustion Environments
The increasing demand of combustion related applications, e.g. transportation, heating and energy production, has led to a series of environmental issues. Understanding the chemical reactions can facilitate the design process in order to create sustainable development. Using laser diagnostics methods such as Laser Induced Fluorescence (LIF), Coherent Anti-stokes Raman Spectroscopy (CARS) and Particle Image Velocimetry (PIV), several key features of flames can be identified. LIF is a species specific detection method that is used to measure concentration in a gas either in one. The method can be converted into two dimensions, called Planar Laser Induced Fluorescence (PLIF), using cylindrical lenses. CARS is a commonly used, non-intrusive temperature measurement that can easily be applied to gases that are above 1000 K, without the heat loss associated with traditional probes. Turbulence in the gas flows is measured using PIV, where particles are seeded into the inlet flow and then a laser is used to visualise the movement of the particles.
Numerical simulations are needed to bridge the gap between understanding the fundamental chemistry in combustion and measuring combustion properties optically. The basis of combustion simulation is the kinetic mechanism, where chemical reactions and their corresponding rates are listed to be used in the simulation. By changing which reactions and tweaking the rates until the simulation match the experimental results, indirect measurements of the chemistry is converted into fundamental knowledge.
Methanol (CH3OH) is a popular renewable fuel that show high potential for both heavy duty vehicles as well as personal transportation and is created from wood and waste material. Burning methanol in engines has been shown to increase the amount of formaldehyde (CH2O) and carbon monoxide (CO) in the exhaust compared to traditional fuels. In addition, trace amount of formic acid (CH2OH) is formed during combustion and corrodes engine and outlet pipes. Understanding the combustion process thoroughly is the key to eliminate unwanted by-product formation.
AramcoMech2.0 is a comprehensive kinetic mechanism for methanol and consists of 2716 reversible reactions and 493 species. The matching of numerical and experimental results thus becomes an optimisation problem in a 2716 dimensional room, with up to 500 optimisation targets (including non-species targets, e.g. temperature and laminar burning velocity). There are both limits in what can actually be measured optically and how much computational power that is available, but it is obvious that a smart way of changing the rate parameters are needed. In this poster, results of a small Genetic Algorithm optimised kinetic mechanism for methanol combustion is presented.
[OIM Poster 2] Electron acceleration and X-ray radiation emission from interacting wakefields
I. Gallardo González, H. Ekerfelt, J. Björklund Svensson, G. Gatti, A. Gonoskov, D. Guenot, M. Hansson, M. Marklund, J. A. Pérez-Hernández, C. Salgado, E. Wallin, G. Zeraouli and O. Lundh
The small-angle interaction of two plasma waves, generated by laser wakefield acceleration , is experimentally studied. A 150 TW laser, with a pulse duration of 27 fs FWHM, is split in two halves and focused in a gas mixture of helium and nitrogen. Each individual laser pulse forms a plasma and generates a plasma wave, which traps and accelerates electrons to relativistic energies by laser wakefield acceleration. The transverse oscillations of the accelerated electrons, induced by the acceleration process, also produces X-ray radiation . The interaction of the two plasma waves is modified by either delaying one of the laser pulses with respect to the other or by shifting the collision point of the wakefields. The properties of the emitted electron beams and the X-ray radiation are studied for different interaction conditions.
[OIM Poster 3] A Snapshot Multispectral Imaging Scheme Using Structured Illumination
Karolina D. Dorozynska and Elias Kristensson.
We present the development of a snapshot multispectral (MS) imaging technique exploiting spatially modulated light. Each encoded excitation source produces an image with a predefined position in the Fourier domain, allowing them to be separated computationally.
[OIM Poster 4] Soft X-ray phase-contrast tomography using laser wakefield acceleration
K. Svendsen, I. Gallardo Gonzalez, M. Hansson, J. Björklund Svensson, H. Ekerfelt, A. Persson and O. Lundh
X-ray phase-contrast imaging allows for non-invasive analysis in low-absorbing materials, such as soft tissue. This implies a vigorous medical or material science application which has yet to be realized on a larger scale due to the requirement on the X-ray source, demanding high flux and small source size. Laser wakefield accelerators generate betatron X-rays fulfilling these criteria and has in recent years proven to be a suitable source for phase-contrast imaging. Using soft X-rays improves the contrast compared to hard X-rays, but trades for lower signal-to-noise ratio as absorption increases. By optimizing the geometrical parameters of the experimental setup with respect to the signal-to-noise ratio, this can be countered to some extent. Laser wakefield acceleration can generate a very small and bright X-ray
source, an important feature for phase-contrast imaging as the resolution is determined by the source size, which in this paper was shown to be on the order of 3 μm. As such, features of this size could be observed in the raw phase-contrast images. These images were further used to do a tomographic reconstruction and and a volume rendering which resolved features on the order of 10 μm.
[OIM Poster 5] Reduction of angular divergence of high intensity laser accelerated proton beams using micro-structured targets
M. Dalui, A. Permogorov, H. Pahl, A. Persson and C.-G. Wahlström
High intensity laser-driven proton acceleration under target normal sheath acceleration scheme is investigated using micro-structured targets. Micron sized conical pits are created on the front side of a flat Al foil (3 µm thick) using laser micromachining. The spatial profiles of the accelerated proton beams from the micro-structured targets are compared with unstructured targetsunder the same experimental conditions. We found that shallow pits (~ 0.1 µm deep) are efficient in reducing the proton beam divergence by a factor of up to three compared to flat foils.
[OIM Poster 6] Why Do We Need Laser Lighting?
With the growing demand for electricity consumption and in particular for lighting there is a need for development of energy effective light sources that can deliver high lumen output. Investigation of laser diode lighting is one of the ways to face this problem.
[OIM Poster 7] HIGH PULSE ENERGY SUPERCONTINUUM FOR COMBINED FLUORESCENCE AND MULTISPECTRAL OPTO-ACOUSTIC TOMOGRAPHY
O.B. Efunbajo , P. Bowen, P.M. Moselund, P.E. Anderson
Organic tissues, exhibit weak acoustic scattering that can be exploited to allow optoacoustic imaging beyond the optical diffusion limit (1 mm in soft tissue) resulting in high resolution images [1, 2]. The fact that constituents of soft tissues, such as water, fat, and blood, have relatively high absorption coefficients at optical frequencies indicates the importance of multispectral probing to provide even better imaging in applications such as biomedicine. For functional imaging based on absorption, windows of interest lie from 400 to 2200 nm .
[OIM Poster 8] BLIPS Lens: add on in Smartphones for Portable Optical Microscopy
Sparsha P, Niranjana Roy, Yuthika Shetty, K C Anish Aithal, Syeda Inaas and Nirmal Mazumder
Optical microscope is an important component in our day to day life from educational laboratories to hospitals for viewing very small objects. One of its major applications is to examine biological specimens for scientific research. It provides clear and magnified images with high resolution which enables us to visualize the micro world. However, commercially available light microscopes are expensive, difficult to maintain, not highly portable and an additional camera is required to capture the images. Since these microscopes are not very feasible in remote areas, there is a need for an alternative. Around the world, mainly in developing countries, a new optical microscope with high sensitivity and low cost is essential, particularly in remote areas with low resources and less facilities. The main aim of this research is to compare the feasibility of smartphone add on BLIPS lens with a standard light microscope. The smartphone based microscope is a self-assembled device, which consists of two stages; one for sample and another for smartphone. The sample can be moved in axial directions using two knobs. In this experiment, digital optical microscope camera is used to capture the images of specimens which are then compared to the images acquired by smartphone based BLIPS add on lenses. Add on lenses (BLIPS) are user-friendly, portable, flexible, cost-effective and are available in a variety of magnifications (ultra ->150x, micro – >100x, macro – 10x, macro plus – 5x). By examining the magnification, resolution, illumination and other optical parameters, we have observed that the images captured in the two instances (light microscope and BLIPS add on lenses using a smartphone), are comparable. Even though, BLIPS lenses do not provide a perfect replacement for the present standard optical microscope, it can be used as a replacement to some extent.
[OIM Poster 9] Investigation of O(1D) chemistry dynamics in premixed methane/air combustion by ozone photolysis
Yupan Bao, Wubin Weng, Kajsa Larsson, Chengdong Kong, Marcus Aldén and Andreas Ehn
The O(1D) chemistry is known to occur on rather rapid timescales. And the investigation of the temporal dynamics of O(1D) chemistry is important for both atmospheric- and plasma-assisted combustion chemistry as the reactions of O(1D) with H2O and CH4 result in production of hydroxyl radicals (OH), which plays a crucial role in eliminating the natural and anthropogenic gaseous pollutants in atmosphere as the most important oxidant[1, 2]. Similarly, as O(1D) is one of the most unstable and active molecules that are formed in plasmas and plasma-assisted combustion [3, 4, 5], the investment of its effect on OH-radical formation can not be ignored.
[OIM Poster 10] Spatially-resolved hydrogen atom detection in flames using backward lasing
Maria Ruchkina, Pengji Ding, Andreas Ehn, Marcus Alden and Joakim Bood
We report on an experimental demonstration of spatially-resolved detection of atomic hydrogen in flames using a single-ended configuration. The lasing signal in a backward direction is obtained by two-photon pumping with 205-nm femtosecond laser pulses.