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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Journal articleAhmad H, Azri MFM, Aidit SN, et al., 2021,
1.3 μm passively Q-Switched bismuth doped fiber laser using Nb<inf>2</inf>C saturable absorber
, Optical Materials, Vol: 116, ISSN: 0925-3467A tunable passively Q-switched fiber laser operating at 1.3 μm was demonstrated using bismuth-doped fiber (BDF) as the gain medium and using niobium carbide (Nb2C) as the saturable absorber (SA). The Nb2C was prepared using the solution casting method, and then fabricated into a film form for ease of integration into the laser cavity. Stable Q-switched pulses were observed as the pump power was increased from 820 to 1037 mW, generating pulses with increasing repetition rates from 10.1 kHz to 13.8 kHz and decreasing pulse widths from 17.54 to 7.58 μs. The all-fiber laser had a center wavelength at 1314 nm with a broad 3-dB bandwidth of 8.35 nm. The maximum output power and pulse energy of the Q-switched laser were 0.74 mW and 53.7 nJ, respectively. The laser was stable when tested for its long-term stability, where the peak frequency remained consistent at 13.8 kHz and the SNRs were maintained to be more than 60 dB throughout the entire test period. To the best of our knowledge, this is the first demonstration for a passively Q-switched fiber laser operating at 1.3 μm wavelength region using BDF as the gain medium.
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Journal articleParmar V, Singh S, Kumar S, et al., 2021,
Thermo-physical modeling and experimental validation of core-shell nanoparticle fabrication of nickel-titanium (nitinol) alloy
, Optics and Laser Technology, Vol: 138, ISSN: 0030-3992Nickel-titanium (nitinol) is a biocompatible shape memory alloy with hyperelasticity and biocompatibility property. A three-dimensional heat diffusion model was used in conjunction with phase explosion theory to explain the formation of core-shell nanoparticles of nitinol. The diffusion model was used to evaluate the melt-pool temperature in the ablation region, while the phase explosion theory was used to estimate the thermophysical expansion and subsequent fragmentation of molten and vaporized nitinol. The mathematical parameters were formulated in conjunction with the experimental results of pulsed laser ablation of core-shell nitinol nanoparticles of various sizes. The model was further employed to predict the sizes of the nanoparticles produced at other higher fluences and the results were experimentally validated.
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Conference paperThipparapu NK, Alam S, Wang Y, et al., 2021,
Tunable Actively Mode-locked Bi-doped O-band Fibre Laser
Widely tunable pulsed fibre laser sources in the O-band (1260-1360nm) are of interest in a variety of fields including spectroscopy, optical communication, time-resolved measurements, and optical system diagnostics [1]. Furthermore, major constituents of biological tissues such as water, oxyhemoglobin, and melanin exhibit minimum optical loss windows in the 1300nm band pointing to applications in medicine [2]. Bi-doped phoshosilicate fibres (BPSFs) have recently been investigated as a promising medium to develop new wavelength lasers and amplifiers in the O-band [3]. They exhibit broad emission spectra which is an important characteristic for developing widely tunable pulsed laser sources [4]. However, to the best of our knowledge, there are no reports of tunable pulsed Bi-doped fibre lasers around 1300nm. Here, we demonstrate an actively tunable mode-locked Bi-doped fibre laser (ML-BDFL) operating in the wavelength region from 1300-1370nm.
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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
Ultra-wideband (UWB) transmission over single-mode fibres (SMFs) is an attractive route in optical transmission, since it allows the available low-loss bandwidth offered in conventional silica SMFs to be utilised more efficiently [1] - [3]. However, data transmission beyond a single span over wavelengths outside the erbium gain band remains challenging, primarily because of the lack of suitable optical amplifiers. Recently, the emergence of bismuth-doped fibre amplifiers (BDFAs) has shown considerable potential for amplified high-speed data communications outside the C+L-bands [4] - [8]. An exciting recent work has reported the development of a BDFA exhibiting a 115nm gain bandwidth, covering the range 1345-1460nm [8]. In this paper, we demonstrate the first data transmission experiment utilising this BDFA as a booster amplifier, and we study its performance across this entire gain band.
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Conference paperWang Y, Thipparapu NK, Richardson DJ, et al., 2021,
High Gain Bi-Doped Fiber Amplifier Operating in the E-band with a 3-dB Bandwidth of 40nm
We report a double-pass bismuth-doped fiber amplifier operating in the E-band providing 38dB gain with 6dB NF for -23dBm input signal at 1430nm. The amplifier 3-dB bandwidth and temperature-dependent-gain coefficient are 40nm and -0.006dB/, respectively.
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Journal articleGratus J, Kinsler P, McCall MW, 2021,
Temporary Singularities and Axions: An Analytic Solution that Challenges Charge Conservation
, ANNALEN DER PHYSIK, Vol: 533, ISSN: 0003-3804- Author Web Link
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- Citations: 2
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Journal articleHong Y, Bottrill KRH, Taengnoi N, et al., 2021,
Numerical and experimental study on the impact of chromatic dispersion on O-band direct-detection transmission.
, Appl Opt, Vol: 60, Pages: 4383-4390The recent emergence of efficient O-band amplification technologies has enabled the consideration of O-band transmission beyond short reach. Despite the O-band being a low chromatic dispersion (CD) window, the impact of CD will become increasingly significant when extending the reach of direct-detection (DD) systems. In this work, we first numerically investigate the 3-dB bandwidth of single-mode fibers (SMF) and the CD-restricted transmission reach in intensity-modulation DD systems, confirming the significant difference between low- and high-dispersion O-band wavelengths. We then carry out experimental transmission studies over SMF for distances of up to 70 km at two different wavelengths, the low-dispersion 1320 nm and the more dispersive 1360 nm, enabled by the use of an O-band bismuth-doped fiber amplifier as a preamplifier at the receiver. We compare three 50-Gb/s optical DD formats, namely, Nyquist on-off keying (OOK), Nyquist 4-ary pulse amplitude modulation (PAM4) and Kramers-Kronig detection-assisted single-sideband quadrature phase shift keying (KK-QPSK) half-cycle subcarrier modulation. Our results show that at both wavelengths, OOK and QPSK exhibit better bit error rate performance than PAM4. When transmitting over 70-km of SMF at the less dispersive wavelength of 1320 nm, 50-Gb/s OOK modulation offers more than 1.5-dB optical power sensitivity improvement at the photodiode (PD) compared to 50-Gb/s QPSK. Conversely, at 1360 nm, the required optical power to the PD can be reduced by more than 3 dB by using QPSK instead of OOK.
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Journal articleCannon T, Lagarto J, Dyer B, et al., 2021,
Characterisation of NADH fluorescence properties under one-photon excitation with respect to temperature, pH and binding to lactate dehydrogenase
, Optical Society of America Continuum, Vol: 4, Pages: 1610-1625Reduced nicotinamide adenine dinucleotide (NADH) is the principal electron donor in glycolysis and oxidative metabolism and is thus recognized as a key biomarker for probing metabolic state. While the fluorescence characteristics of NADH have been investigated extensively, there are discrepancies in the published data due to diverse experimental conditions, instrumentation and microenvironmental parameters that can affect NADH fluorescence. Using a cuvette-based time-resolved spectrofluorimeter employing one-photon excitation at 375 nm, we characterized the fluorescence intensity, lifetime, spectral response, anisotropy and time-resolved anisotropy of NADH in aqueous solution under varying microenvironmental conditions, namely temperature, pH, and binding to lactate dehydrogenase (LDH). Our results demonstrate how temperature, pH, and binding partners each impact the fluorescence signature of NADH and highlight the complexity of the fluorescence data when different parameters produce competing effects. We hope that the data presented in this study will provide a reference for potential sources of variation in experiments measuring NADH fluorescence.
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Journal articleTaengnoi N, Bottrill KRH, Hong Y, et al., 2021,
Experimental characterization of an o-band bismuth-doped fiber amplifier.
, Opt Express, Vol: 29, Pages: 15345-15355The recent emergence of bismuth-doped fiber amplifiers (BDFAs) offers the potential to transmit high-speed WDM signals over long distances in the O-band spectral region, thereby greatly enhancing the scope of systems utilizing these wavelengths. In this paper, we present a comprehensive experimental study on several basic characteristics of an O-band BDFA based on a phosphosilicate optical fiber, including the frequency-dependent noise figure, gain tilt (static and dynamic), transient response, and polarization dependent gain. We discuss our findings and their implications on the use of BDFA technology in high bit-rate multichannel systems.
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Journal articleMurray RT, Chandran AM, Battle RA, et al., 2021,
Seeded optical parametric generation in CdSiP2 pumped by a Raman fiber amplifier at 124 µm
, Optics Letters, Vol: 46, Pages: 2039-2039, ISSN: 0146-9592We report a seeded optical parametric generator (OPG) producing tunable radiation from 4.2–4.6 µm. The seeded OPG employs a 13 mm long CdSiP2 (CSP) crystal cut for non-critical phase-matching, pumped by a nanosecond-pulsed, MHz repetition rate Raman fiber amplifier system at 1.24 µm. A filtered, continuous-wave fiber supercontinuum source at 1.72 µm is used as the seed. The source generates up to 0.25 W of mid-infrared (MIR) idler power with a total pump conversion of 42% (combined signal and idler).
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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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Journal articleKerridge-Johns WR, Jaillot J-B, Damzen MJ, 2021,
Sampling a vortex from a Gaussian beam using a wedge-plate shearing interferometer
, Applied Optics, Vol: 60, Pages: 3510-3510, ISSN: 1559-128XMany vortex-generation techniques have been developed to address a range of potential applications, exploiting their unique amplitude and phase profiles and their possession of orbital angular momentum. In this work, we present what may be the simplest method of vortex beam generation, requiring only a wedged optic: the wedge-plate shearing interferometer (WPSI). We show that the WPSI can reflect a first order Laguerre–Gaussian vortex beam (LG01) with a theoretical purity of >99% from an input fundamental Gaussian beam, with 98% LG01 purity experimentally demonstrated. We demonstrate 1% power conversion with a route to 14%. The monolithic WPSI is a simple, compact, and highly stable device, which can operate at any wavelength that the material is transparent to. We anticipate that it will be useful where sampling a robust, high-purity vortex beam from a Gaussian laser beam is required, including low-cost vortex generation for metrology or education.
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Conference paperDvinskikh L, Harding S, Sparks H, et al., 2021,
High speed imaging of calcium dynamics in cardiomyocytes with a flexible light-sheet fluorescence microscope
, Biophotonics Congress 2021 -
Journal articleCollart C, Ciccarelli A, Ivanovitch K, et al., 2021,
The migratory pathways of the cells that form the endocardium, dorsal aortae, and head vasculature in the mouse embryo
, BMC DEVELOPMENTAL BIOLOGY, Vol: 21, ISSN: 1471-213X- Author Web Link
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- Citations: 4
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Journal articleAhmad H, Aidit SN, Ooi SI, et al., 2021,
1.3 µm dissipative soliton resonance generation in Bismuth doped fiber laser.
, Sci Rep, Vol: 11In this work, a Figure-9 (F9) bismuth-doped fiber laser (BiDFL) operating in the dissipative soliton resonance (DSR) regime is presented. The 1338 nm laser used a BiDF as the active gain medium, while a nonlinear amplifying loop mirror (NALM) in an F9 configuration was employed to obtain high energy mode-locked pulses. The wave breaking-free rectangular pulse widened significantly in the time domain with the increase of the pump power while maintaining an almost constant peak power of 0.6 W. At the maximum pump power, the mode-locked laser delivered a rectangular-shaped pulse with a duration of 48 ns, repetition rate of 362 kHz and a radio-frequency signal-to-noise ratio of more than 60 dB. The maximum output power was recorded at around 11 mW with a corresponding pulse energy of 30 nJ. This is, to the best of the author's knowledge, the highest mode-locked pulse energy obtained at 1.3 μm as well as the demonstration of an NALM BiDFL in a F9 configuration.
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Conference paperMurray RT, Chandran AM, Battle RA, et al., 2021,
Seeded optical parametric generation in CdSiP2 pumped by a nanosecond pulsed, MHz repetition rate Raman fiber amplifier at 1.24 µm
, Nonlinear Frequency Generation and Conversion: Materials and Devices XX, Publisher: SPIE, Pages: 1-10We report a CdSiP2 (CSP) based seeded optical parametric generator (OPG), emitting sub-nanosecond duration, 3 MHz repetition rate, wavelength tunable mid-infrared (MIR) light at 4.2-4.6 μm. We generate up to 0.25 W at 4.2 μm with a total pump conversion efficiency of 42%. The OPG is pumped by a 1.24 μm Raman fiber amplifier system. This is the first demonstration of pumping CSP with a Raman fiber source in this region, and we show that Raman fiber sources in the near-infrared (NIR) are ideal pump sources for non-critically phasematched (NCPM) CSP devices. Pumping CSP at 1.24 μm permits the use of NCPM whilst decreasing the negative effects of both two-photon absorption and linear absorption losses, when compared to conventional 1 μm pumping. This offers a potential advantage for MIR power scaling of CSP parametric devices due to a reduced thermal load in the crystal from residual pump absorption. The OPG is seeded with a continuous-wave fiber supercontinuum source emitting radiation in the 1.7 μm region, to lower the threshold pump intensity required for efficient conversion. NCPM and temperature tuning of the crystal allow for simple wavelength tuning of the idler radiation. We report on laser damage induced by elevated crystal temperatures, which we propose is linked to the decrease in CSP bandgap energy with increasing temperature.
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Journal articleKondo H, Ratcliffe CDH, Hooper S, et al., 2021,
Single-cell resolved imaging reveals intra-tumor heterogeneity in glycolysis, transitions between metabolic states, and their regulatory mechanisms
, CELL REPORTS, Vol: 34, ISSN: 2211-1247- Author Web Link
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- Citations: 54
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Journal articleWang Y, Thipparapu NK, Richardson DJ, et al., 2021,
Ultra-Broadband Bismuth-Doped Fiber Amplifier Covering a 115-nm Bandwidth in the O and e Bands
, Journal of Lightwave Technology, Vol: 39, Pages: 795-800, ISSN: 0733-8724In this article, we experimentally demonstrate an all-fiber optical amplifier using Bi-doped phosphosilicate fiber (BPSF) operating in both the O-band and the E-band, providing >20 dB gain from 1345 to 1460 nm for an input signal power of -23 dBm. A maximum gain of 31 dB with a noise figure (NF) of 4.8 dB was achieved at 1420 nm for -23 dBm input signal, whereas for an input signal power of -10 dBm it was 26 dB with a NF of 5.3 dB. The in-band OSNR of the proposed Bi-doped fiber amplifier (BDFA) was >22 dB from 1345 to 1460 nm for a -23 dBm input signal. The gain coefficient was found to be 0.04 dB/mW for a -23 dBm input signal. Also, the temperature dependent gain and NF performance of the BDFA within -40 to +60 °C were characterized. The temperature-dependent-gain (TDG) coefficient for a -23 dBm input signal was found to be -0.015 dB/°C at a signal wavelength of 1420 nm where the BDFA gain is maximum, while for an input signal power of -10 dBm it was -0.01 dB/°C at 1420 nm. The TDG coefficient of the proposed BDFA from 1350-1460 nm was in the range from -0.079 to -0.008 dB/°C. The BDFA gain and NF performance were also measured and compared using BPSFs with different unsaturable loss (UL) characteristics.
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Journal articleJones DC, Alexandrov Y, Curry N, et al., 2021,
Multidimensional spectroscopy and imaging of defects in synthetic diamond: excitation-emission-lifetime luminescence measurements with multiexponential fitting and phasor analysis
, Journal of Physics D: Applied Physics, Vol: 54, Pages: 1-13, ISSN: 0022-3727We report the application of phasor analysis and nonlinear iterative fitting to complex spatial and spectroscopic luminescence decay data obtained from multidimensional microscopy of a CVD diamond grown on a HPHT substrate. This spectral and lifetime-resolved analysis enabled spatial mapping of variations in concentrations of nitrogen vacancy (NV) defects in both charge states and the quenching of NV− defects, as well as the identification of SiV− luminescence. These imaging and spectroscopic modalities may be important for reliable fabrication of quantum devices based on such defects in diamond, which will require well-defined and characterised quantum electronic properties.
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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 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 paperThipparapu NK, Alam S, Wang Y, et al., 2021,
Tunable actively mode-locked bi-doped O-band fibre laser
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Conference paperWang Y, Thipparapu NK, Richardson DJ, et al., 2021,
High gain Bi-doped fiber amplifier operating in the E-band with a 3-dB bandwidth of 40nm
We report a double-pass bismuth-doped fiber amplifier operating in the E-band providing 38dB gain with 6dB NF for -23dBm input signal at 1430nm. The amplifier 3-dB bandwidth and temperature-dependent-gain coefficient are 40nm and -0.006dB/?, respectively.
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Conference paperHong Y, Taengnoi N, Bottrill KRH, et al., 2021,
Experimental Demonstration of 50-Gb/s/λ O-band CWDM Direct-Detection Transmission over 100-km SMF
, ISSN: 2162-108XWe demonstrate the first single-sideband 50-Gb/s/λ coarse WDM direct-detection transmission in the O-band. It is shown that the Kramers-Kronig-detection assisted single-sideband transmission exhibits significant OSNR sensitivity improvements over double-sideband transmission, enabling up to 100-km reach.
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