Publications
See a list of publications below or visit the Photonics academic staff page and click on a particular member of staff to access their personal web page, which includes a list of their own publications.
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Conference paperHong Y, Bottrill KRH, Wang Y, et al., 2021,
O+E-band transmission over 50-km SMF using a broadband bismuth doped fibre amplifier
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Conference paperThipparapu NK, Alam S, Wang Y, et al., 2021,
Tunable actively mode-locked bi-doped O-band fibre laser
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Conference paperDeepak MD, Karthik P, Kumar SS, et al., 2021,
Comparative Study of Feature Extraction Using Different Transform Techniques in Frequency Domain
, Pages: 2835-2846, ISSN: 1876-1100The compressed sensing is a mathematical approach of reconstructing a signal that is acquired from the dimensionally reduced data coefficients/less number of samples, i.e., less than the Niquist rate. The data coefficients are high-frequency components and low-frequency components. The high-frequency components are due to the rapid changes in the images (edges) and low-frequency correspond are due to slow varying information (continuous surface). The idea is to retain only low-frequency components, i.e., the significant components that constitute the compressed signal. This compressed signal is the sparse signal which is so helpful during medical scenario. During the Medical Resonance Imaging (MRI) scans, the patient undergoes many kinds difficulties like uncomfortness, patients are afraid of the scanning devices, he/she cannot be stable or changing his body positions slightly. Due to all these reasons, there can be a chance of acquiring only the less number of samples during the process of MRI scan. Even though the numbers of samples is less than the Nyquist rate, the reconstruction is possible by using the compressed sensing technique. The work has been carried out in the frequency domain to achieve the sparsity. The comparative study is done on percentage of different levels of sparsity of the signal. This can be verified by using peak signal-to-noise ratio (PSNR), root mean square error (RMSE), and structural similarity (SSIM) methods which are calculated between the reference image and the reconstructed image.
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Conference paperSparks H, Almagro J, Behrens A, et al., 2021,
Dual-view oblique plane microscopy
Dual-view Oblique Plane Microscopy (dOPM) enables single-objective multi-view light-sheet fluorescence microscopy. This talk introduces the dOPM concept and demonstrates optical resolution performance with exemplar 3D datasets of fluorescence bead samples and fixed multicellular spheroids.
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Conference paperMurray RT, Chandran AM, Battle RA, et al., 2021,
CdSiP<inf>2</inf> based mid-infrared optical parametric sources pumped with Raman fiber amplifiers
CdSiP2 (CSP) is a nonlinear optical semiconductor which can phasematch pump wavelengths throughout the near-infrared (NIR) to generate mid-infrared (MIR) light through parametric three-wave mixing. In this work, we investigate the unique combination of NIR Raman fiber amplifiers around 1.24 µm and non-critical phasematching in CSP, to demonstrate tunable sources in the 4-5 µm MIR region.
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Journal articleHimabindu DD, Kumar SP, 2021,
A Survey on Computer Vision Architectures for Large Scale Image Classification using Deep Learning
, International Journal of Advanced Computer Science and Applications, Vol: 12, Pages: 105-120, ISSN: 2158-107XThe advancement in deep learning is increasing day-by-day from image classification to language understanding tasks. In particular, the convolution neural networks are revived and shown their performance in multiple fields such as natural language understanding, signal processing, and computer vision. The property of translational invariance for convolutions has made a huge advantage in the field of computer vision to extract feature invariances appropriately. When these convolutions trained using back-propagation tend to prove their results ability to outperform existing machine vision techniques by overcoming the various hand-engineered machine vision models. Hence, a clear understanding of current deep learning methods is crucial. These convolution neural networks have proven to show their performance by attaining state-of-the-art performance in computer vision over years when applied on humongous data. Hence in this survey, we detail a set of state-of-the-art models in image classification evolved from the birth of convolutions to present ongoing research. Each state-of-the-art model evolved in the successive year is illustrated with architecture schema, implementation details, parametric tuning and their performance. It is observed that the neural architecture construction i.e. a supervised approach for an image classification problem is evolved as data construction with cautious augmentations i.e., a self-supervised approach. A detailed evolution from neural architecture construction to augmentation construction is illustrated by provided appropriate suggestions to improve the performance. Additionally, the implementation details and the appropriate source for the execution and reproducibility of results are tabulated.
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Conference paperGeberbauer JWT, Kerridge-Johns WR, Damzen MJ, 2021,
>30 W vortex laser using vortex output coupler
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Conference paperHong Y, Deligiannidis S, Taengnoi N, et al., 2021,
Performance-enhanced amplified o-band WDM transmission using machine learning based equalization
We investigate the performance of a machine learning-based equalization in an amplified 4×50-Gb/s O-band WDM system. The results show that the scheme offers significant receiver sensitivity improvements over decision-feedback equalization, especially at more dispersive wavelengths.
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Conference paperBerk J, Paterson C, Foreman MR, 2021,
Tracking using surface plasmon leakage radiation speckle
An approach capable of label-free sensing and tracking of single nanoscale particles using interference between light scattered from the particle and a plasmon leakage radiation speckle field is introduced. Simulations show nanometre level tracking accuracy.
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Conference paperDarling C, Davis SPX, Kumar S, et al., 2021,
Single-Shot Volumetric Imaging Using Optical Projection Tomography
, ISSN: 1605-7422We present a single-shot volumetric imaging method, utilising optical projection tomography. We record projections simultaneously, implementing compressive sensing and machine learning to record up to 70 (camera limited) 1x1x1.9mm volumes/second.
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Conference paperLightley J, Görlitz F, Kumar S, et al., 2021,
ROBUST OPTICAL AUTOFOCUS SYSTEM UTILIZING NEURAL NETWORKS APPLIED TO AUTOMATED MULTIWELL PLATE STORM MICROSCOPY
, ISSN: 1605-7422We present a robust, low-cost neural network-based optical autofocus system that can operate over a range of ±100µm with submicron precision, enabling automated high-content super-resolved imaging with a 1.3 NA objective lens.
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Conference paperKalita R, Lightley J, Kumar S, et al., 2021,
Single-shot quantitative phase contrast using polarisation-resolved differential phase microscopy
, ISSN: 1605-7422We present a robust, low-cost single-shot implementation of differential phase microscopy utilising a polarisation-sensitive camera to simultaneously acquire 4 images from which the phase gradients and quantitative phase image can be calculated.
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Conference paperChandran AM, Battle RA, Murray RT, et al., 2021,
743 nm Source by SHG of a Cascaded Phosphosilicate Raman Fiber Amplifier
We demonstrate a nanosecond-pulsed 743 nm source by second harmonic generation of a cascaded phosphosilicate Raman fiber amplifier operating at 1485 nm. The source emits >1 W of 743 nm average power at a 5 MHz repetition rate.
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Conference paperGeberbauer JWT, Kerridge-Johns WR, Damzen MJ, 2021,
>30 W vortex laser using vortex output coupler
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Conference paperTawy G, Minassian A, Damzen MJ, 2021,
8.5W linear and 3.6W Ring TEM<inf>00</inf> diode-pumped alexandrite lasers
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Conference paperDarling C, Davis SPX, Kumar S, et al., 2021,
Single-Shot Volumetric Imaging Using Optical Projection Tomography
, European Conferences on Biomedical Optics - Advances in Microscopic Imaging III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X -
Conference paperKalita R, Lightley J, Kumar S, et al., 2021,
Single-shot quantitative phase contrast using polarisation-resolved differential phase microscopy
, European Conferences on Biomedical Optics - Advances in Microscopic Imaging III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X -
Conference paperTawy G, Minassian A, Damzen MJ, 2021,
8.5W Linear and 3.6W Ring TEM<sub>00</sub> Diode-Pumped Alexandrite Lasers
, Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), Publisher: IEEE -
Conference paperGeberbauer JWT, Kerridge-Johns WR, Damzen MJ, 2021,
>30 W Vortex Laser Using Vortex Output Coupler
, Conference on Lasers and Electro-Optics Europe / European Quantum Electronics Conference (CLEO/Europe-EQEC), Publisher: IEEE -
Conference paperLightley J, Gorlitz F, Kumar S, et al., 2021,
ROBUST OPTICAL AUTOFOCUS SYSTEM UTILIZING NEURAL NETWORKS APPLIED TO AUTOMATED MULTIWELL PLATE STORM MICROSCOPY
, European Conferences on Biomedical Optics - Advances in Microscopic Imaging III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X -
Journal articleJones B, McGlone ER, Fang Z, et al., 2021,
Genetic and biased agonist-mediated reductions in β-arrestin recruitment prolong cAMP signalling at glucagon family receptors
, Journal of Biological Chemistry, Vol: 296, Pages: 1-15, ISSN: 0021-9258Receptors for the peptide hormones glucagon-like peptide-1 (GLP-1R), glucose-dependent insulinotropic polypeptide (GIPR) and glucagon (GCGR) are important regulators of insulin secretion and energy metabolism. GLP-1R agonists have been successfully deployed for the treatment of type 2 diabetes, but it has been suggested that their efficacy is limited by target receptor desensitisation and downregulation due to recruitment of β-arrestins. Indeed, recently described GLP-1R agonists with reduced β-arrestin-2 recruitment have delivered promising results in preclinical and clinical studies. We therefore aimed to determine if the same phenomenon could apply to the closely related GIPR and GCGR. In HEK293 cells depleted of both β-arrestin isoforms the duration of G protein-dependent cAMP/PKA signalling was increased in response to the endogenous ligand for each receptor. Moreover, in wild-type cells, “biased” GLP-1, GCG and GIP analogues with selective reductions in β-arrestin-2 recruitment led to reduced receptor endocytosis and increased insulin secretion over a prolonged stimulation period, although the latter effect was only seen at high agonist concentrations. Biased GCG analogues increased the duration of cAMP signalling, but this did not lead to increased glucose output from hepatocytes. Our study provides a rationale for development of GLP-1R, GIPR and GCGR agonists with reduced β-arrestin recruitment, but further work is needed to maximally exploit this strategy for therapeutic purposes.
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Journal articleConey A, Damzen M, 2021,
High-energy diode-pumped alexandrite amplifier development with applications in satellite-based lidar
, Journal of the Optical Society of America B: Optical Physics, Vol: 38, Pages: 209-219, ISSN: 0740-3224Efficient, wavelength-tunable diode-pumped alexandrite laser systems offer the potential for a more versatile, satellite-based lidar source compared to fixed wavelength Nd:YAG systems and non-space compliant lamp-pumped alexandrite. In this paper, we develop a strategy to enable the high-energy operation required for atmospheric lidar based on an efficient diode-pumped Master-Oscillator Power-Amplifier (MOPA) system design. A novel multi-pass ‘diamond’ slab amplifier geometry is introduced alongside the experimental results of the world’s first diode-pumped alexandrite amplifier producing a gain of 2.13 in a demonstration system. A diode-pumped Q-switched alexandrite oscillator is presented with a record-highest pulse energy of 3.80 mJ. Detailed optimisation of a two-stage amplifier design is studied numerically and maximised with temperature, wavelength and pump pulse duration to produce 50 mJ pulse energy. This forms part of an optimised alexandrite MOPA design capable of high pulse energy, showing the future potential of diode pumped alexandrite for satellite-based atmospheric lidar.
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Journal articleAhmad H, Samion MZ, Kamely AA, et al., 2020,
Multiwavelength Brillouin Generation in Bismuth-Doped Fiber Laser with Single- And Double-Frequency Spacing
, Journal of Lightwave Technology, Vol: 38, Pages: 6886-6896, ISSN: 0733-8724Multiwavelength fiber lasers operating in the 1.3 μm wavelength region are of great interest as they complement existing systems in the conventional optical communication band of 1.55 μm. In this work, a multiwavelength Brillouin fiber laser with single- and double-Brillouin frequency spacings operating in 1.3 μm is proposed and demonstrated using a dispersion compensating fiber (DCF) as the Brillouin gain medium. A bismuth-doped fiber serves as the laser gain medium. At the maximum pump power of 1021 mW and with the Brillouin pump set at 11 dBm, up to 7 Brillouin Stokes lines with a wavelength spacing of 0.074 nm are obtained in the single-spaced configuration. In the case of the double-spaced configuration, 14 Stokes lines are generated with a wavelength spacing of 0.15 nm between the even Stokes lines. By tuning the central wavelength of the Brillouin pump, both laser configurations are wavelength-tunable with a range of 93 nm and 19 nm for the single-spaced and double-spaced Brillouin lasers respectively. This is, to the best of the author's knowledge, the first demonstration of a multiwavelength/Brillouin laser using a bismuth-doped fiber as the laser gain medium.
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SoftwareGong H, Wenjun G, Neil M, 2020,
HexSimProcessor
This repository is for the publication: "GPU-accelerated real-time reconstruction in Python of three-dimensional datasets from structured illumination microscopy with hexagonal patterns". It includes: raw data from experiments and simulations, the code for generating the simulated data, and the code for post-processing the raw data.
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Conference paperTewari S, Agrawal U, Verma S, et al., 2020,
Ensemble model for COVID-19 detection from chest X-ray scans using image segmentation, fuzzy color and stacking approaches
Coronavirus is a virus of RNA-type that can infect both humans and animal and causes a wide variety of respiratory infections. In humans, it also causes pneumonia. Since coronavirus has been declared a pandemic, Reverse Transcription Polymerase Chain Reaction (RT-PCR) has been the standard method for detection but is a time consuming operation and due to sudden surge in demand it has a high cost. In this study, coronavirus was detected from X-ray scans of chest using a deep learning model consisting of fuzzy image enhancement, offline data augmentation, image segmentation and classification through Convolutional Neural Network. For training and classification, an ensembeled model consisting of the features of VGG-16, ResNet-50 and MobileNetV2 was built and optimized with bayesian optimization. The proposed model achieved an overall accuracy of 96.34%. The precision, recall and F1-Score for COVID-19 class was 100%, 96% and 98% respectively.
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Journal articleSparks H, Dent L, Bakal C, et al., 2020,
Dual-view oblique plane microscopy (dOPM)
, Biomedical Optics Express, Vol: 11, Pages: 7204-7220, ISSN: 2156-7085We present a new folded dual-view oblique plane microscopy (OPM) techniquetermed dOPM that enables two orthogonal views of the sample to be obtained by translating apair of tilted mirrors in refocussing space. Using a water immersion 40× 1.15 NA primaryobjective, deconvolved image volumes of 200 nm beads were measured to have full width athalf maxima (FWHM) of 0.35±0.04 μm and 0.39±0.02 μm laterally and 0.81±0.07 μm axially.The measured z-sectioning value was 1.33±0.45 μm using light-sheet FWHM in the frames ofthe two views of 4.99±0.58 μm and 4.89±0.63 μm. To qualitatively demonstrate that the systemcan reduce shadow artefacts while providing a more isotropic resolution, a multi-cellularspheroid approximately 100 μm in diameter was imaged.
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Journal articleWang S, Wang Y, Thipparapu NK, et al., 2020,
Tunable CW Bi-Doped Fiber Laser System from 1320 to 1370 nm Using a Fiber Bragg Grating
, IEEE Photonics Technology Letters, Vol: 32, Pages: 1443-1446, ISSN: 1041-1135Here we present a fully fiberized Bi-doped ring laser incorporating a fiber Bragg grating (FBG) operating at a wavelength of 1340nm, which provides 172mW of continuous-wave output power with a slope efficiency of 35%. In addition, we demonstrate a wavelength-tunable version of the laser, which can be tuned from 1320nm to 1370nm by employing a home-made mechanically tunable FBG. Within the whole 50nm tuning band the laser maintains the output power of more than 100mW and the slope efficiency of more than 25%. A maximum output power of 165mW is achieved over the wavelength range of 1330-1340nm. The linewidth of tunable laser is 0.04nm.
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Conference paperGouveia RM, Lepert G, Gupta S, et al., 2020,
Biomechanical Modulation Therapy: Stem Cell Therapy Without the Stem Cells for the Treatment of Severe Ocular Burns
, Trans-Agency Scientific Meeting on Developing Medical Countermeasures to Treat the Acute and Chronic Effects of Ocular Chemical Toxicity, Publisher: ELSEVIER IRELAND LTD, Pages: S8-S8, ISSN: 0378-4274 -
Conference paperKerridge-Johns WR, Jaillot J-B, Damzen MJ, 2020,
Shear plate Interferometer for complex angular momentum field generation
, Frontiers in Optics, Publisher: OSA, Pages: 1-1We show that a shear plate interferometer can generate high purity complex angular momentum states and is simple, cheap, compact, and could operate in wavelength regions where optics for conventional techniques are not available.
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Conference paperWysoczanski R, Baker JR, Fenwick P, et al., 2020,
Analysis of defective phagocytosis in COPD using super-resolution microscopy and automated bacterial quantification
, Publisher: EUROPEAN RESPIRATORY SOC JOURNALS LTD, ISSN: 0903-1936
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