Mr. Derek J. Cassidy Profile

Derek J. Cassidy

Senior Optical Specialist

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Author

Publications (15)

Proceedings Article | 11 July 2023 Presentation

Analysing beam coherence through self-written waveguides

Derek Cassidy, John Sheridan

Proceedings Volume 12574, 125740P (2023) https://doi.org/10.1117/12.2661703

KEYWORDS: Waveguides, Beam analyzers, Photopolymers, Coherence (optics), Signal attenuation, Optical testing, Speckle, Reflectivity, Polymers, Photosensitive materials

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Proceedings Article | 30 May 2022 Presentation

Measuring the optical response self-written waveguides within polymer sensors

Derek Cassidy, John Sheridan

Proceedings Volume PC12151, PC121510B (2022) https://doi.org/10.1117/12.2619798

KEYWORDS: Waveguides, Sensors, Polymers, Polymeric sensors, Polymer multimode waveguides, Wave propagation, Photopolymers, Optical sensors, Environmental sensing, Analytical research

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Proceedings Article | 30 May 2022 Presentation

Image processing and coherence using SWW as a transmission medium

Derek Cassidy, John Sheridan

Proceedings Volume PC12151, PC121510D (2022) https://doi.org/10.1117/12.2622040

KEYWORDS: Coherence (optics), Image processing, Photopolymers, Waveguides, Signal attenuation, Optical testing, Speckle, Reflectivity, Polymers, Photosensitive materials

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Proceedings Article | 13 April 2020 Presentation + Paper

Optical analysis and characterization of self-written and coupled waveguides

Derek Cassidy, Ra'ed Mullalah, Min Wan, John Healy, John Sheridan

Proceedings Volume 11367, 113670X (2020) https://doi.org/10.1117/12.2555970

KEYWORDS: Waveguides, Refractive index, Photopolymers, Light wave propagation, Polymers, Beam propagation method, Geometrical optics, Integrated optics, Optical fibers, Connectors

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Proceedings Article | 1 April 2020 Open Access

Testing the coherence of light waves within self-written waveguides

Derek Cassidy, Min Wan, Ra'ed Malallah, John Healy, John Sheridan

Proceedings Volume 11367, 113671H (2020) https://doi.org/10.1117/12.2556013

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Proceedings Article | 2 March 2020 Paper

Sub-pixel motion estimation for terahertz imaging

Min Wan, Christopher Duignan, Derek Cassidy, John Healy, John Sheridan

Proceedings Volume 11279, 112792E (2020) https://doi.org/10.1117/12.2547340

KEYWORDS: Terahertz radiation, Motion estimation, Cameras, Imaging systems, Image fusion, Millimeter wave imaging, Sensors, Image resolution, Diffraction, Spatial resolution

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Proceedings Article | 14 May 2019 Presentation

Characterization of self-written waveguide within PVA/AA (Conference Presentation)

Derek Cassidy, Ra'ed Malallah, John Healy, Min Wan, John Sheridan

Proceedings Volume 11030, 1103008 (2019) https://doi.org/10.1117/12.2520968

KEYWORDS: Waveguides, Signal attenuation, Birefringence, Optical fibers, Light sources, Coherence (optics), Analytical research, Optical fabrication, Optical power meters, Light wave propagation

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The fabrication of Polyvinyl Alcohol/Acrylamide (PVA/AA) and the addition of a photo-sensitizer have been fully investigated. The creation of self-written waveguides (SWW) has also received much attention and their results have been very promising. In this paper we look at the optical loss across the SWW and also subject the SWW to coherence testing to analyze the wave form and measure any degradation in the optical signal. With the fabrication of the PVA/AA we use a photo-sensitizer or dye which is Erythrosine B (EB), which is sensitive to wavelength of λ = 532nm. We characterize a multi-mode (MM) fiber across various aspects such as attenuation profile and birefringence. We then cut the optical fiber and prepare it for cleaving. The fiber ends are then cleaved and then set into a V-Groove. The fiber ends are 7mm apart and in direct line or optical trajectory. This is then covered with a soluble form of photo-sensitized PVA/AA. When the PVA/AA is cured an optical light source (OLS) is connected to one end of the fiber. This OLS has a broadband light source capability from 400nm to 1700nm. An optical power meter (OPM) is connected to the other end of the fiber, this OLP also has the capability to receive and analyze wavelengths within the spectrum 400nm to 1700nm. The OPM is turned on the wavelength λ = 532nm propagates along the fiber until it enters the PVA/AA. The self-writing process begins and with the change in refractive index and the introduction of polymer chains a SWW is created. The SWW is now situated between the two fiber ends with an length matching the fiber distance of 7mmThe wavelength then enters the open optical fiber and the propagates along the fiber to the OPM. At this stage the analyses of the 532nm wavelength gets underway and the optical fiber link is re-characterized. At this stage a wavelength is characterized and measure against the original attenuation profile (AP) and birefringence measurements. The wavelength is also examined under spectral analyses using a spectrum analyzer and compared to the original wave form to measure interference and coherence. This will allow us to understand the characteristics of a SWW with fibers interconnecting and exposing the wavelength directly to the PVA/AA within its structure. The tests carried out investigate attenuation profile (AP), birefringence, polarization effects and interference. The SWW is characterized so that future use as a directional splitter/coupler created within a SWW can be used effectively within an integrated devise and within communication networks.

Proceedings Article | 30 April 2019 Presentation + Paper

Self-written net waveguides using photopolymer media

Ra'ed Malallah, Derek Cassidy, Inbarasan Muniraj, Min Wan, Harsha Vardhan Maraka, John Sheridan

Proceedings Volume 11026, 110260U (2019) https://doi.org/10.1117/12.2521183

KEYWORDS: Waveguides, Photopolymers, Polymers, Photopolymerization, Refractive index, Light wave propagation, Photopolymer media, Holography

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Proceedings Article | 23 April 2019 Presentation + Paper

Terahertz quantitative metrology using 300 GHz in-line digital holography

Min Wan, Hui Yuan, Dovilė Čibiraitė, Derek Cassidy, Alvydas Lisauskas, John Healy, Hartmut Roskos, Viktor Krozer, John Sheridan

Proceedings Volume 11030, 110300R (2019) https://doi.org/10.1117/12.2520787

KEYWORDS: Terahertz radiation, Holograms, Digital holography, Sensors, Holography, Metrology, 3D image processing, CMOS sensors, Imaging systems, Signal detection

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Proceedings Article | 16 April 2019 Paper

Coupling of self-written waveguides (SWW) in photopolymer and reverse manipulation

Derek Cassidy, Ra'ed Mulallah, Min Wan, John Healy, John Sheridan

Proceedings Volume 11029, 110290Y (2019) https://doi.org/10.1117/12.2520933

KEYWORDS: Refractive index, Waveguides, Geometrical optics, Photopolymers, Light wave propagation, Polymers, Beam propagation method, Connectors, Optical fibers, Visible radiation

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Proceedings Article | 24 May 2018 Paper

Photon-counted integral holography using orthographic projection images

Min Wan, Inbarasan Muniraj, Ni Chen, Derek Cassidy, John Healy, James Ryle, John Sheridan

Proceedings Volume 10677, 106773G (2018) https://doi.org/10.1117/12.2307581

KEYWORDS: Holograms, Holography, 3D image processing, Photon counting, Digital holography, Image acquisition, Imaging systems, Neptunium, Computer generated holography, Visualization

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Proceedings Article | 17 May 2018 Paper

Optical characterization of photopolymer material SWW at 532nm and for use at 850nm and 1300nm

Derek Cassidy, Ra'ed Malallah, Min Wan, John Healy, John Sheridan

Proceedings Volume 10683, 106832J (2018) https://doi.org/10.1117/12.2306163

KEYWORDS: Mirrors, Connectors, Waveguides, Optical fibers, Light wave propagation, Calibration, Optical power meters, Optical testing, Light sources, Wave propagation

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Proceedings Article | 8 March 2018 Paper

Self-bending of optical waveguides in a dry photosensitive medium

Ra'ed Malallah, Min Wan, Inbarasan Muniraj, Derek Cassidy, John Sheridan

Proceedings Volume 10528, 105281L (2018) https://doi.org/10.1117/12.2287215

KEYWORDS: Waveguides, Optical fibers, Photopolymers, Refractive index, Light wave propagation, Photosensitive materials, Optical fiber cables, Radio propagation, Nonlinear optics, Diffusion

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SPIE Journal Paper | 14 June 2017

Choice of optical system is critical for the security of double random phase encryption systems

Inbarasan Muniraj, Changliang Guo, Ra’ed Malallah, Derek Cassidy, Liang Zhao, James Ryle, John Healy, John Sheridan

OE, Vol. 56, Issue 06, 063103, (June 2017) https://doi.org/10.1117/12.10.1117/1.OE.56.6.063103

KEYWORDS: Computer security, Optical authentication, Systems modeling, Computer programming, Optical image encryption, Image encryption

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Proceedings Article | 16 May 2017 Presentation + Paper

Investigating nonlinear distortion in the photopolymer materials

Ra'ed Malallah, Derek Cassidy, Inbarasan Muniraj, Liang Zhao, James Ryle, John Sheridan

Proceedings Volume 10228, 1022805 (2017) https://doi.org/10.1117/12.2263749

KEYWORDS: Photopolymers, Waveguides, Light wave propagation, Laser beam propagation, Refractive index, Distortion, Diffraction, Polymer multimode waveguides, Photorefractive polymers, Polymers, 3D modeling, Photopolymer media

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Showing 5 of 15 publications

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