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Analysis of the Imaging Characteristics of Holographic Waveguides Recorded in Photopolymers. Polymers (Basel) 2020; 12:polym12071485. [PMID: 32635228 PMCID: PMC7408443 DOI: 10.3390/polym12071485] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 11/17/2022] Open
Abstract
In this work, we study the imaging characteristics of an optical see-through display based on a holographic waveguide. To fabricate this device, two transmission holograms are recorded on a photopolymer material attached to a glass substrate. The role of the holograms is to couple the incident light between air and the glass substrate, accomplishing total internal reflection. The role of noise reflection gratings and shrinkage on the imaging characteristics of the device will be also explored. The holograms (slanted transmission gratings with a spatial frequency of 1690 lines/mm) were recorded on a polyvinyl alcohol acrylamide holographic polymer dispersed liquid crystal (HPDLC) material. We will show that sufficient refractive index modulation is achieved in the material, in order to obtain high diffraction efficiencies. We will demonstrate that the final device acts as an image formation system.
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Malallah R, Cassidy D, Wan M, Muniraj I, Healy JJ, Sheridan JT. Optical Trajectory Manipulations Using the Self-Written Waveguide Technique. Polymers (Basel) 2020; 12:polym12071438. [PMID: 32605110 PMCID: PMC7408574 DOI: 10.3390/polym12071438] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 06/07/2020] [Accepted: 06/24/2020] [Indexed: 10/25/2022] Open
Abstract
This study is novel for several reasons: We used a thin drop cast layer of dry photosensitive materials to study the behaviors of wet photopolymer media using microscopic distances during the Self-Written Waveguide (SWW) process; then, we examined the self-trajectories formed inside the solid material. The results provide a framework for theoretical and experimental examinations by handling the effects of manipulating the alignment of fibers. The other main advantage of these techniques is their lightweight, easy to process, highly flexible, and ultimately low-cost nature. First, the SWW process in wet photopolymer media (liquid solutions) was examined under three cases: single-, counter-, and co-fiber exposure. Then, the SWWs formed inside the solid material were examined along with the effects of manipulating the alignment of the fibers. In all cases, high precision measurements were used to position the fiber optic cables (FOCs) before exposure using a microscope. The self-writing process was indirectly monitored by observing (imaging) the light emerging from the side of the material sample during SWW formation. In this way, we examined the optical waveguide trajectories formed in Acrylamide/Polyvinyl Alcohol (AA/PVA), a photopolymer material (sensitized at 532 nm). First, the transmission of light by this material is characterized. Then, the bending and merging of the waveguides that occur are investigated. The predictions of our model are shown to qualitatively agree with the observed trajectories. The largest index changes taking place at any time during exposure, i.e., during SWW formation, are shown to take place at the positions where the largest exposure light intensity is present. Typically, such maxima exist close to the input face. The first maximum is referred to as the location of the Primary Eye. Other local maxima also appear further along the SWW and are referred to as Secondary Eyes, i.e., eyes deeper within the material.
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Affiliation(s)
- Ra’ed Malallah
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
- Physics Department, Faculty of Science, University of Basrah, Garmat Ali, Basrah 61004, Iraq
- Correspondence: (R.M.); (J.T.S.); Tel.: +353-1-716-1927 (J.T.S.); Fax: +353-1-283-0921 (J.T.S.)
| | - Derek Cassidy
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
| | - Min Wan
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
| | - Inbarasan Muniraj
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
| | - John J. Healy
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
| | - John T. Sheridan
- School of Electrical and Electronic Engineering, College of Engineering and Architecture, University College Dublin, D 4 Dublin, Ireland; (D.C.); (M.W.); (I.M.); (J.J.H.)
- Correspondence: (R.M.); (J.T.S.); Tel.: +353-1-716-1927 (J.T.S.); Fax: +353-1-283-0921 (J.T.S.)
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Suar M, Melchert O, Rahlves M, Roth B. Experimental and theoretical study of the formation process of photopolymer based self-written waveguides. OPTICS EXPRESS 2019; 27:38326-38336. [PMID: 31878601 DOI: 10.1364/oe.27.038326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/03/2019] [Indexed: 06/10/2023]
Abstract
The realization of optical interconnects between multimode (MM) optical fibers and waveguides based on a self-writing process in photopolymer media represents an efficient approach for fast and easy-to-implement connection of light-guiding elements. When light propagates through photopolymer media, it modulates the material properties of the media and confines the spreading of the light beam to create a waveguide along the beam propagation direction. This self-writing process can be realized with a single photopolymer medium and is also suited to connect optical fibers or waveguides with active elements such as light sources and detectors. Numerical simulations of the underlying light-induced polymerization process is carried out by using a diffusion based material model which takes account both monomer diffusion and its conversion to polymer chains in regions exposed to light fields. In this work experimental results obtained from a one-polymer approach are validated with theoretical predictions from the diffusion model. The study involved the demonstration of temporal dynamics and transmittance from self-written waveguide (SWW) couplers during the self-writing process. The measured attenuation coefficient from experiment αexperiment = (8.43 ± 0.3) × 10-5 dB/µm showed good agreement with the theoretically predicted attenuation coefficient αsimulation = 7.93 × 10-5 dB/µm, thus demonstrating a successful application of the diffusion model to epoxy based acrylate SWWs. For comparison, attenuation measurements between optical fibers with SWWs as interconnects and one without SWW, i.e. with an air gap in between, were performed. The obtained results reveal that the theoretical approach correctly describes the waveguide formation process so that in the next step the studies can be extended towards including further relevant parameters such as temperature.
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Fernández R, Bleda S, Gallego S, Neipp C, Márquez A, Tomita Y, Pascual I, Beléndez A. Holographic waveguides in photopolymers. OPTICS EXPRESS 2019; 27:827-840. [PMID: 30696163 DOI: 10.1364/oe.27.000827] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/13/2018] [Indexed: 06/09/2023]
Abstract
The possibilities that offer the holographic optical elements for photovoltaic and "see through display" applications open new windows for holographic recording materials. In this sense, some specific characteristics are required for each particular application. Waveguides are one of the key elements for these applications. Photopolymers are one of the most competitive candidates for waveguide fabrication. In this work, we evaluate the performance of one example from each of three families of photopolymer material in fabrication of a 633nm waveguide. Firstly, polyvinyl alcohol acrylamide, PVA/AA, the second one, a nanoparticle-thiol-ene, NPC, and on the last place a penta/hexa-acrylate based polymer with dispersed nematic liquid crystal molecules, PDLC. We study the critical role of the material and in particular, spatial resolution for this application.
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Malallah R, Cassidy D, Muniraj I, Ryle JP, Healy JJ, Sheridan JT. Self-written waveguides in photopolymer. APPLIED OPTICS 2018; 57:E80-E88. [PMID: 30117925 DOI: 10.1364/ao.57.000e80] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/28/2018] [Indexed: 06/08/2023]
Abstract
Self-written waveguide (SWW) trajectories fabricated inside a dry photopolymer bulk material, acrylamide/polyvinyl alcohol (AA/PVA), are studied. Their production using both Gaussian and Laguerre-Gauss exposing (writing) light beams, output from optical fibers, is explored. The formation of the primary and secondary eyes is also discussed. Furthermore, the interactions that take place when two counterpropagating beams pass through the photopolymer material (both Gaussian and Laguerre-Gauss) are examined. In all cases experimental and theoretical results are presented. Good agreement between the predictions of the proposed model and experimental observations are demonstrated.
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Li H, Qi Y, Guo C, Malallah R, Sheridan JT. Holographic characterization of diffraction grating modulation in photopolymers. APPLIED OPTICS 2018; 57:E107-E117. [PMID: 30117910 DOI: 10.1364/ao.57.00e107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 05/22/2018] [Indexed: 06/08/2023]
Abstract
In general, the holographic grating refractive index profiles in photopolymer materials are not identical to the exposing pattern. During exposure, high harmonics of the fundamental refractive index period are generated within the layer volume. A set of equations to calculate the amplitudes of the higher harmonics of refractive index induced in the grating is introduced. Then, an algorithm involving the use of the 3D nonlocal photopolymerization-driven diffusion model is presented and applied to calculate the resulting grating diffraction efficiencies. The experimental observation that the grating diffraction efficiency cannot reach the theoretical maximum value (ηmax=100%) and that, in the case of over-modulation, the minimum value (ηmin=0%) is also never achieved, are explained theoretically. The predictions of the simulations are also fit to experimental data for an acrylamide/polyvinyl alcohol photopolymer material with good agreement being achieved.
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Biria S, Morim DR, An Tsao F, Saravanamuttu K, Hosein ID. Coupling nonlinear optical waves to photoreactive and phase-separating soft matter: Current status and perspectives. CHAOS (WOODBURY, N.Y.) 2017; 27:104611. [PMID: 29092420 DOI: 10.1063/1.5001821] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Nonlinear optics and polymer systems are distinct fields that have been studied for decades. These two fields intersect with the observation of nonlinear wave propagation in photoreactive polymer systems. This has led to studies on the nonlinear dynamics of transmitted light in polymer media, particularly for optical self-trapping and optical modulation instability. The irreversibility of polymerization leads to permanent capture of nonlinear optical patterns in the polymer structure, which is a new synthetic route to complex structured soft materials. Over time more intricate polymer systems are employed, whereby nonlinear optical dynamics can couple to nonlinear chemical dynamics, opening opportunities for self-organization. This paper discusses the work to date on nonlinear optical pattern formation processes in polymers. A brief overview of nonlinear optical phenomenon is provided to set the stage for understanding their effects. We review the accomplishments of the field on studying nonlinear waveform propagation in photopolymerizable systems, then discuss our most recent progress in coupling nonlinear optical pattern formation to polymer blends and phase separation. To this end, perspectives on future directions and areas of sustained inquiry are provided. This review highlights the significant opportunity in exploiting nonlinear optical pattern formation in soft matter for the discovery of new light-directed and light-stimulated materials phenomenon, and in turn, soft matter provides a platform by which new nonlinear optical phenomenon may be discovered.
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Affiliation(s)
- Saeid Biria
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, USA
| | - Derek R Morim
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Fu An Tsao
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Kalaichelvi Saravanamuttu
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - Ian D Hosein
- Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, New York 13244, USA
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Malallah R, Li H, Kelly DP, Healy JJ, Sheridan JT. A Review of Hologram Storage and Self-Written Waveguides Formation in Photopolymer Media. Polymers (Basel) 2017; 9:E337. [PMID: 30971014 PMCID: PMC6418820 DOI: 10.3390/polym9080337] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 07/28/2017] [Accepted: 08/01/2017] [Indexed: 11/16/2022] Open
Abstract
Photopolymer materials have received a great deal of attention because they are inexpensive, self-processing materials that are extremely versatile, offering many advantages over more traditional materials. To achieve their full potential, there is significant value in understanding the photophysical and photochemical processes taking place within such materials. This paper includes a brief review of recent attempts to more fully understand what is needed to optimize the performance of photopolymer materials for Holographic Data Storage (HDS) and Self-Written Waveguides (SWWs) applications. Specifically, we aim to discuss the evolution of our understanding of what takes place inside these materials and what happens during photopolymerization process, with the objective of further improving the performance of such materials. Starting with a review of the photosensitizer absorptivity, a dye model combining the associated electromagnetics and photochemical kinetics is presented. Thereafter, the optimization of photopolymer materials for HDS and SWWs applications is reviewed. It is clear that many promising materials are being developed for the next generation optical applications media.
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Affiliation(s)
- Ra'ed Malallah
- School of Electrical and Electronic Engineering, UCD Communications and Optoelectronic Research Centre, University College Dublin, Belfield, Dublin 4, Ireland.
- Physics Department, Faculty of Science, University of Basrah, Garmat Ali, Basrah, Iraq.
| | - Haoyu Li
- Department of Biomedical Engineering, Stony Brook University, State University of New York, Stony Brook, NY 11794, USA.
| | - Damien P Kelly
- School of Electrical and Electronic Engineering, UCD Communications and Optoelectronic Research Centre, University College Dublin, Belfield, Dublin 4, Ireland.
| | - John J Healy
- School of Electrical and Electronic Engineering, UCD Communications and Optoelectronic Research Centre, University College Dublin, Belfield, Dublin 4, Ireland.
| | - John T Sheridan
- School of Electrical and Electronic Engineering, UCD Communications and Optoelectronic Research Centre, University College Dublin, Belfield, Dublin 4, Ireland.
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Lu C, Park S, Richner TJ, Derry A, Brown I, Hou C, Rao S, Kang J, Moritz CT, Fink Y, Anikeeva P. Flexible and stretchable nanowire-coated fibers for optoelectronic probing of spinal cord circuits. SCIENCE ADVANCES 2017; 3:e1600955. [PMID: 28435858 PMCID: PMC5371423 DOI: 10.1126/sciadv.1600955] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Accepted: 02/10/2017] [Indexed: 05/24/2023]
Abstract
Studies of neural pathways that contribute to loss and recovery of function following paralyzing spinal cord injury require devices for modulating and recording electrophysiological activity in specific neurons. These devices must be sufficiently flexible to match the low elastic modulus of neural tissue and to withstand repeated strains experienced by the spinal cord during normal movement. We report flexible, stretchable probes consisting of thermally drawn polymer fibers coated with micrometer-thick conductive meshes of silver nanowires. These hybrid probes maintain low optical transmission losses in the visible range and impedance suitable for extracellular recording under strains exceeding those occurring in mammalian spinal cords. Evaluation in freely moving mice confirms the ability of these probes to record endogenous electrophysiological activity in the spinal cord. Simultaneous stimulation and recording is demonstrated in transgenic mice expressing channelrhodopsin 2, where optical excitation evokes electromyographic activity and hindlimb movement correlated to local field potentials measured in the spinal cord.
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Affiliation(s)
- Chi Lu
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Seongjun Park
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Thomas J. Richner
- Departments of Rehabilitation Medicine and Physiology and Biophysics, Center for Sensorimotor Neural Engineering, UW Institute for Neuroengineering, University of Washington, Seattle, WA 98195, USA
| | - Alexander Derry
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Imogen Brown
- Department of Materials, University of Oxford, Oxford OX1 3PH, UK
| | - Chong Hou
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Siyuan Rao
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jeewoo Kang
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chet T. Moritz
- Departments of Rehabilitation Medicine and Physiology and Biophysics, Center for Sensorimotor Neural Engineering, UW Institute for Neuroengineering, University of Washington, Seattle, WA 98195, USA
| | - Yoel Fink
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Advanced Functional Fabrics of America Inc., 500 Technology Square, NE47-525, Cambridge, MA 02139, USA
| | - Polina Anikeeva
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Li H, Dong Y, Xu P, Qi Y, Guo C, Sheridan JT. Beam self-cleanup by use of self-written waveguide generated by photopolymerization. OPTICS LETTERS 2015; 40:2981-2984. [PMID: 26125347 DOI: 10.1364/ol.40.002981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A novel method for multimode fiber (MMF) laser-beam cleanup is introduced based on the optically induced growth and interaction of self-written waveguides (SWWs) in a photopolymer material. Theoretically, it is predicted that when the light is introduced into a free-radical photopolymerizable system from a MMF, the incident multichannel and structured beam shape can be caused to merge to form a single-channel Gaussian-like beam under specific exposure and material conditions. Experimental validation was carried out using a dry acrylamide/polyvinyl alcohol (AA/PVA) photopolymer sample. This work opens the door to studies involving self-developing laser beam cleanup and also to possible applications in photonic telecommunication systems and integrated optical devices.
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Kawana M, Takahashi JI, Guo J, Tomita Y. Measurement of polymerization-shrinkage evolution during curing in photopolymer with a white-light Fabry-Pérot interferometer. OPTICS EXPRESS 2015; 23:15356-15364. [PMID: 26193515 DOI: 10.1364/oe.23.015356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We propose a simple method of measuring polymerization-shrinkage evolution during curing in photopolymer. The real-time spectral fringe analysis of a broadband beam transmitted through a Fabry-Pérot etalon supported by a photopolymer film provides the shrinkage evolution during curing. For the proof-of-principle demonstration a blue-sensitized nanoparticle-polymer composite material is used. It is shown that the measured shrinkage dynamics are well correlated with the photo-calorimetric conversion dynamics of monomer to polymer. We also discuss a discrepancy in steady-state shrinkage between our proposed and holographic Bragg-angle detuning measurements.
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