Dr. Shaif-ul U. Alam Profile

Dr. Shaif-ul U. Alam

Principal Research Fellow at Optoelectronic Research Ctr

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Author

Publications (20)

SPIE Journal Paper | 6 December 2018 Open Access

Ultrafast laser-scanning optical resolution photoacoustic microscopy at up to 2 million A-lines per second

Thomas John Allen, Josh Spurrell, Martin Berendt, Olumide Ogunlade, Shaif Alam, Edward Zhang, David Richardson, Paul Beard

JBO, Vol. 23, Issue 12, 126502, (December 2018) https://doi.org/10.1117/12.10.1117/1.JBO.23.12.126502

KEYWORDS: Video, Fiber lasers, Ear, Optical resolution, Photoacoustic microscopy, Imaging systems, Photoacoustic spectroscopy, Fiber optics sensors, Sensors, Laser optics

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Proceedings Article | 15 March 2018 Presentation

Compact fibre laser system with 15mJ pulse energy for photoacoustic tomography (Conference Presentation)

Thomas Allen, Martin Berendt, Shaif-ul Alam, Nam Huynh, David Richardson, Paul Beard

Proceedings Volume 10494, 104941Z (2018) https://doi.org/10.1117/12.2288820

KEYWORDS: Fiber lasers, Photoacoustic tomography, Tomography, Photoacoustic spectroscopy, Acquisition tracking and pointing, Acoustics, Laser scanners, 3D scanning, Laser tissue interaction, Pulsed laser operation

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Photoacoustic signals are typically generated using Q-switched Nd:YAG pumped OPO systems, as they can provide the necessary nanosecond pulse durations with mJ pulse energies required for photoacoustic tomography. However, these sources are often bulky, require external water cooling and regular maintenance and provide low pulse repetition frequencies (PRF<100Hz) thus limiting image frame rate. Fibre lasers can overcome these limitations and additionally offer much greater flexibility in their temporal output characteristics (e.g. pulse shaping and duration). Although fibre lasers have been used in optical-resolution photoacoustic microscopy, they have found limited application in widefield photoacoustic tomography (PAT) due to the relatively low pulse energy (<1mJ) provided by commercial systems. These low pulse energies are a consequence of small core diameter (<25m) fibres required to achieve a high beam quality. However, for widefield PAT, high beam quality is not a requirement and therefore fibre lasers with larger core diameters (>100m) can be used, enabling significantly higher pulse energies (>10mJ) to be achieved. A novel compact fibre laser which uses a custom drawn large core diameter fibre (100m) to provide high pulse energies (15mJ) and variable PRFs (100Hz-1kHz) and pulse durations (10-400ns) has been developed and evaluated. The fibre laser was combined with a fast Fabry Perot (FP) scanner in order to evaluate its suitability for PAT of biological tissue. The high PRF (>400Hz) of the laser has allowed tomographic images of the microvasculature of the palm of a hand to be obtained in less than one second, significantly quicker than previously achieved with a FP scanner. In addition, the ability to arbitrarily vary the temporal shape of the laser pulse offers new opportunities for controlling the acoustic frequency content of the photoacoustic signal in order to optimise penetration depth and image resolution. For example, the laser pulse duration can be increased in order to shift the acoustic frequency components to lower frequencies which are less attenuated by tissue acoustic absorption and thus improve SNR. To investigate these concepts, a tissue mimicking phantom was imaged for a range of tailored excitation pulses (e.g. different pulse durations, trains of pulses) and their effect on the contrast to noise ratio (CNR) and image resolution observed. A novel compact fibre laser, able to provide higher pulse energies (>10mJ) than previously reported and with enhanced functionality is presented. It is demonstrated that fibre lasers are a viable alternative to standard Q-switched lasers for photoacoustic tomographic applications in medicine and biology.

Proceedings Article | 20 February 2017 Presentation + Paper

Exploring nonlinear pulse propagation, Raman frequency conversion and near octave spanning supercontinuum generation in atmospheric air-filled hollow-core Kagomé fiber

Seyedmohammad Abokhamis Mousavi, Hans Christian Hansen Mulvad, Natalie Wheeler, Peter Horak, Thomas Bradley, Shaif-ul Alam, John Hayes, Seyed Reza Sandoghchi, David Richardson, Francesco Poletti

Proceedings Volume 10088, 100880G (2017) https://doi.org/10.1117/12.2253706

KEYWORDS: Raman spectroscopy, Atmospheric propagation, Frequency conversion, Supercontinuum generation, Atmospheric optics, Nonlinear optics, Atmospheric modeling, Nonlinear dynamics, Wave propagation, Nitrogen, Glasses, Data modeling, Laser damage threshold

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Proceedings Article | 28 January 2017 Paper

Recent progress in SDM amplifiers

Yongmin Jung, Qiongyue Kang, Saurabh Jain, Shaif-ul Alam, David Richardson

Proceedings Volume 10130, 1013004 (2017) https://doi.org/10.1117/12.2252014

KEYWORDS: Fiber amplifiers, Optical amplifiers, Space division multiplexing, Multiplexing, Optical fibers, Optical properties, Optical isolators, Optical components, Optical communications, Telecommunications, Collimators, Optical filters, Diodes, Free space optics

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Proceedings Article | 17 March 2016 Presentation + Paper

Novel fibre lasers as excitation sources for photoacoustic tomography and microscopy

T. Allen, M. Berendt, J. Spurrell, S. Alam, E. Zhang, D. Richardson, P. Beard

Proceedings Volume 9708, 97080W (2016) https://doi.org/10.1117/12.2211733

KEYWORDS: Fiber lasers, Photoacoustic tomography, Photoacoustic spectroscopy, Imaging systems, Laser development, Acquisition tracking and pointing, Image acquisition, Photoacoustic imaging, Microscopy, Optical resolution

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Proceedings Article | 11 March 2016 Paper

Highly efficient Yb-free Er-La-Al doped ultra-low Na large mode area single-trench fiber laser

Deepak Jain, Shaiful Alam, Yongmin Jung, Pranabesh Barua, Martin Velazquez, Jayanta Sahu

Proceedings Volume 9728, 97280W (2016) https://doi.org/10.1117/12.2211336

KEYWORDS: Fiber lasers, Laser development, Erbium, Fiber amplifiers, Doping, Numerical simulations, Refractive index, Cladding, Laser resonators, Absorption

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Proceedings Article | 18 February 2013 Paper

Supercontinuum generation with femtosecond pulse fiber amplified VECSELs

C. Robin Head, Ho-Yin Chan, James Feehan, David Shepherd, Shaif-ul Alam, Anne Tropper, Jonathan H. Price, Keith Wilcox

Proceedings Volume 8606, 860608 (2013) https://doi.org/10.1117/12.2004240

KEYWORDS: Supercontinuum generation, Mirrors, Femtosecond phenomena, Ytterbium, Dispersion, Picosecond phenomena, Mode locking, Fiber amplifiers, Second-harmonic generation, Semiconductor lasers

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Proceedings Article | 9 May 2012 Paper

High power high repetition rate picosecond optical parametric oscillator pumped by frequency doubled all-fiber Yb-doped MOPA

Florian Kienle, Shaif-ul Alam, Peh Siong Teh, Dejiao Lin, Jonathan H. Price, David Hanna, David Richardson, David Shepherd

Proceedings Volume 8433, 843302 (2012) https://doi.org/10.1117/12.922852

KEYWORDS: Optical parametric oscillators, Crystals, Mirrors, Semiconductor lasers, Picosecond phenomena, Fiber amplifiers, Microscopy, Lithium, Optical amplifiers, Resonators

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Proceedings Article | 16 February 2012 Paper

An all-fiber PM MOPA pumped high-power OPO at 3.82 µm based on large aperture PPMgLN

Dejiao Lin, Shaif-ul Alam, Yonghang Shen, Tao Chen, David Richardson

Proceedings Volume 8237, 82371K (2012) https://doi.org/10.1117/12.906364

KEYWORDS: Optical parametric oscillators, Crystals, Phase modulation, Fiber amplifiers, Polarization, Optical amplifiers, Fiber lasers, Absorption, Diodes, Ytterbium

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Proceedings Article | 16 February 2012 Paper

High energy in-band pumped erbium doped pulse fibre laser

E. Lim, S. Alam, D. Richardson

Proceedings Volume 8237, 82371V (2012) https://doi.org/10.1117/12.908429

KEYWORDS: Fiber lasers, Wavelength division multiplexing, Erbium, Optical amplifiers, Q switched lasers, Pulsed laser operation, Cladding, Bragg cells, Fiber amplifiers, Absorption

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Proceedings Article | 17 May 2011 Paper

500km remote interrogation of optical sensor arrays

Ed Austin, Qian Zhang, Shaif-ul Alam, Michalis Zervas, Radan Slavik, Periklis Petropoulos, Phil Nash, David Richardson

Proceedings Volume 7753, 77532M (2011) https://doi.org/10.1117/12.886078

KEYWORDS: Sensors, Interferometry, Optical amplifiers, Seismic sensors, Fiber amplifiers, Optical sensors, Acoustics, Fiber optics sensors, Optical arrays, Optical fibers

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Proceedings Article | 1 March 2011 Paper

Use of a pulsed fibre laser as an excitation source for photoacoustic tomography

Thomas Allen, Shaiful Alam, Edward Zhang, Jan Laufer, David Richardson, Paul Beard

Proceedings Volume 7899, 78991V (2011) https://doi.org/10.1117/12.875291

KEYWORDS: Fiber lasers, Photoacoustic spectroscopy, Photoacoustic tomography, Signal detection, Pulsed fiber lasers, Tissue optics, Laser tissue interaction, Photoacoustic imaging, Imaging systems, Tissues

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Proceedings Article | 11 February 2011 Paper

Simultaneous excitation of selective multiple Raman Stokes wavelengths (green-yellow-red) using shaped multi-step pulses from an all-fiber MOPA system

Dejiao Lin, Shaif-ul Alam, Peh Siong Teh, Kang Kang Chen, David Richardson

Proceedings Volume 7914, 79140O (2011) https://doi.org/10.1117/12.874520

KEYWORDS: Raman spectroscopy, Phase modulation, Second-harmonic generation, Optical amplifiers, Fiber amplifiers, Fiber lasers, Polarization, Cladding, Pulse shaping, Optical fibers

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Proceedings Article | 3 March 2010 Paper

Recent advances in microstructured fibers for laser delivery and generation

J. Hayes, M. Petrovich, F. Poletti, P. Horak, N. G. Broderick, Xian Feng, S. Dasgupta, Wei Loh, Debashri Ghosh, Mrinmay Pal, Shyamal Bhadra, K. Chen, J. H. Price, S. Alam, D. Richardson

Proceedings Volume 7580, 758010 (2010) https://doi.org/10.1117/12.847923

KEYWORDS: Optical fibers, Glasses, Solids, Supercontinuum generation, Mid-IR, Visible radiation, Fiber lasers, Scattering, Laser development, Micro optical fluidics

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Proceedings Article | 18 February 2010 Paper

Excitation of individual Raman Stokes lines of up-to ninth order using rectangular shaped optical pulses at 530 nm

Kang Kang Chen, Shaif-ul Alam, Christophe Codemard, Andrew Malinowski, David Richardson

Proceedings Volume 7582, 75820I (2010) https://doi.org/10.1117/12.845933

KEYWORDS: Raman spectroscopy, Optical amplifiers, Fiber amplifiers, Second-harmonic generation, Fiber lasers, Polarization, Optical isolators, Crystals, Frequency conversion, Wave propagation

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Proceedings Article | 17 February 2010 Paper

Over 55W of frequency doubled light at 530 nm pumped by an all-fiber diffraction limited picosecond fibre MOPA

Shaif-ul Alam, Kangkang Chen, John Hayes, Dejiao Lin, Andrew Malinowski, Howard Baker, Natalia Trela, Roy McBride, David Richardson

Proceedings Volume 7580, 758007 (2010) https://doi.org/10.1117/12.845929

KEYWORDS: Picosecond phenomena, Polarization, Crystals, Second-harmonic generation, Amplifiers, Diodes, Optical amplifiers, Scanning probe microscopy, Fiber amplifiers, Fiber lasers

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Proceedings Article | 26 September 2009 Paper

Visible and mid-IR output using a fibre laser pump source

James Beedell, Ian Elder, Kang Kang Chen, Shaif-ul Alam, David Richardson, Duncan Hand

Proceedings Volume 7483, 748307 (2009) https://doi.org/10.1117/12.835443

KEYWORDS: Optical parametric oscillators, Second-harmonic generation, Mirrors, Mid-IR, Crystals, Optical amplifiers, Fiber lasers, Fiber amplifiers, Picosecond phenomena, Ytterbium

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Proceedings Article | 24 February 2009 Paper

Externally modulated diode-seeded Yb3+-doped fiber MOPA pumped high power optical parametric oscillator

S. U. Alam, Kangkang Chen, Dejiao Lin, Yonghang Shen, Shuangshuang Cai, Bo Wu, Peipei Jiang, Andrew Malinowski, David Richardson

Proceedings Volume 7197, 71970H (2009) https://doi.org/10.1117/12.813658

KEYWORDS: Optical parametric oscillators, Optical amplifiers, Fiber amplifiers, Crystals, Fiber lasers, Polarization, Pulse shaping, Pulsed laser operation, Optical isolators, Signal attenuation

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Proceedings Article | 22 April 2005 Paper

High pulse energy Q-switched laser in MOPA configuration

K. Vysniauskas, L. Hickey, S. Alam, F. Ghiringhelli, M. Zervas, A. Piper, B. Thomsen, A. Malinowski, D. Richardson

Proceedings Volume 5709, (2005) https://doi.org/10.1117/12.601573

KEYWORDS: Amplifiers, Q switched lasers, Pulsed laser operation, Fiber lasers, Bragg cells, Semiconductor lasers, Ytterbium, Laser systems engineering, Q switching, Laser applications

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Proceedings Article | 3 July 2003 Paper

High-power fiber lasers: new developments

Johan Nilsson, Jayanta Sahu, Yoochan Jeong, W. Clarkson, R. Selvas, Anatoly Grudinin, Shaiful Alam

Proceedings Volume 4974, (2003) https://doi.org/10.1117/12.478310

KEYWORDS: Fiber lasers, Cladding, Ytterbium, Glasses, Diodes, Absorption, Laser damage threshold, Optical amplifiers, High power fiber lasers, Laser crystals

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