1. B. Imran Akca

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    1. Mentioned In 16 Articles

    2. On-chip polarization beam splitter design for optical coherence tomography

      On-chip polarization beam splitter design for optical coherence tomography
      Polarization beam splitters (PBSs) are central elements for polarization handling. Here, we present the design of an ultra-broadband, low-loss, and easy-to-fabricate PBS based on a silicon nitride asymmetrical directional coupler for polarization-sensitive optical coherence tomography systems. The phase difference between transverse electric and transverse magnetic modes is introduced by using straight waveguides with different widths and an offset between them. A bent waveguide is placed close to the end of ...
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    3. On-chip Mach-Zehnder interferometer for OCT systems

      On-chip Mach-Zehnder interferometer for OCT systems
      By using integrated optics, it is possible to reduce the size and cost of a bulky optical coherence tomography (OCT) system. One of the OCT components that can be implemented on-chip is the interferometer. In this work, we present the design and characterization of a Mach-Zehnder interferometer consisting of the wavelength-independent splitters and an on-chip reference arm. The Si 3 N 4 was chosen as the material platform as it ...
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    4. Non-moving scanner design for OCT systems

      Non-moving scanner design for OCT systems
      n this work, a novel beam scanner design based on non-moving parts is introduced which will eliminate the phase and inaccuracy problems of the mechanical scanners while providing two times imaging speed improvement for optical coherence tomography systems. The design is comprised of electro-optically activated switches that are placed on the sample arm. For the example considered here, lateral resolution of 20 m, and lateral scanning range of 1 mm ...
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    5. Design of a high-speed multiple-reference optical coherence tomography system

      Design of a high-speed multiple-reference optical coherence tomography system
      he imaging speed of a time domain optical coherence tomography (OCT) system is limited by the speed of the moving mirror. As a solution to this problem an integrated-optics-based multiple-reference TD-OCT system is presented in this work. The reference and sample lights will be sequentially tapped out at multiple locations using electro-optically controlled switches. For the design considered here an axial resolution of 20 m and a depth range of ...
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    6. Observation of sound-induced corneal vibrational modes by optical coherence tomography

      Observation of sound-induced corneal vibrational modes by optical coherence tomography
      The mechanical stability of the cornea is critical for maintaining its normal shape and refractive function. Here, we report an observation of the mechanical resonance modes of the cornea excited by sound waves and detected by using phase-sensitive optical coherence tomography. The cornea in bovine eye globes exhibited three resonance modes in a frequency range of 50-400 Hz. The vibration amplitude of the fundamental mode at 80-120 Hz was ~8 ...
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    7. Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties

      Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties
      Most techniques measuring corneal biomechanics in vivo are biased by side factors. We demonstrate the ability of optical coherence tomographic (OCT) vibrography to determine corneal material parameters, while reducing current prevalent restrictions of other techniques (such as intraocular pressure (IOP) and thickness dependency). Modal analysis was performed in a finite-element (FE) model to study the oscillation response in isolated thin corneal flaps/eye globes and to analyse the dependency of ...
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    8. Miniature spectrometer and beam splitter for an optical coherence tomography on a silicon chip

      Miniature spectrometer and beam splitter for an optical coherence tomography on a silicon chip
      Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated optics, we assemble the central components of a spectral-domain OCT system on a silicon chip. The spectrometer comprises an arrayed-waveguide grating with 136-nm free spectral range and 0.21-nm wavelength resolution. The ...
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    9. Advanced integrated spectrometer designs for miniaturized optical coherence tomography systems

      Advanced integrated spectrometer designs for miniaturized optical coherence tomography systems
      Optical coherence tomography (OCT) has enabled clinical applications that revolutionized in vivo medical diagnostics. Nevertheless, its current limitations owing to cost, size, complexity, and the need for accurate alignment must be overcome by radically novel approaches. Exploiting integrated optics, the central components of a spectral-domain OCT (SD-OCT) system can be integrated on a chip. Arrayed-waveguide grating (AWG) spectrometers with their high spectral resolution and compactness are excellent candidates for on-chip ...
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    10. Spectral-domain optical coherence tomography on a silicon chip (Thesis)

      Spectral-domain optical coherence tomography on a silicon chip (Thesis)
      Optical coherence tomography (OCT) is a non-invasive optical technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine and industry (e.g. materials testing, quality assurance, and process control). Current state-of-the-art OCT systems operate in the frequency domain, using either a broad-band light source and a spectrometer, known as spectral-domain OCT (SD-OCT), or a rapidly tunable laser, known as swept-source OCT (SS-OCT). Both systems contain a multitude ...
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    11. Feature Of The Week 6/3/12: Towards OCT On a Chip - A Hard Goal but One that Could Eventually Revolutionize OCT Systems and Applications

      Feature Of The Week 6/3/12: Towards OCT On a Chip - A Hard Goal but One that Could Eventually Revolutionize OCT Systems and Applications
      ..., size, and cost penalties in OLCR and, hence, OCT systems. For more information see recent Article. Courtesy Imran Akca from the University of Twente. Miniaturization of Optical Coherence Tomography (OCT) systems is one...
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    12. Polarization-Independent Enhanced-Resolution Arrayed-Waveguide Grating Used in Spectral-Domain Optical Low-Coherence Reflectometry

      Polarization-Independent Enhanced-Resolution Arrayed-Waveguide Grating Used in Spectral-Domain Optical Low-Coherence Reflectometry
      The performance of an arrayed-waveguide grating (AWG) as an integrated spectrometer in spectral-domain optical low-coherence reflectometry (SD-OLCR) is significantly improved. By removing the output waveguides of the AWG, the depth range is enhanced from 1 to 3.3 mm at 800 nm and 4.6 mm at 1300 nm. Periodic signal fading, that was previously observed in the sensitivity roll-off curve in depth ranging measurements, is shown to be evoked ...
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    13. Performance Improvement and Birefringence Investigation of Spectral Domain Optical Coherence Tomography Using a Modified Arrayed Waveguide Grating

      Performance Improvement and Birefringence Investigation of Spectral Domain Optical Coherence Tomography Using a Modified Arrayed Waveguide Grating
      An arrayed-waveguide grating (AWG) with its high accuracy and stability is a powerful tool for spectral analysis. We investigate its potential for spectral-domain optical coherence tomography (SD-OCT). A silicon-oxynitride-based AWG spectrometer for the 800 nm wavelength range is designed for on-chip SD-OCT systems. By removing the output waveguides of the AWG, the depth range is significantly enhanced. In addition, the effect of polarization dependency of the AWG on sensitivity roll-off ...
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    14. Toward Spectral-domain Optical Coherence Tomography on a Chip

      Toward Spectral-domain Optical Coherence Tomography on a Chip
      We present experimental results of a spectraldomain optical coherence tomography system based on an integrated optical spectrometer. A 195-channel arrayedwaveguide- grating (AWG) spectrometer with 0.4-nm channel spacing centered at 1300 nm and a 125-channel AWG with 0.16-nm channel spacing centered at 800 nm have been fabricated in silicon oxynitride waveguide technology. Interferometric distance measurements have been performed by launching light from a broadband source into a free-space Michelson ...
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    15. Silicon oxynitride technology for integrated optical solutions in biomedical applications

      Silicon oxynitride technology for integrated optical solutions in biomedical applications
      Silicon oxynitride, a dielectric material with excellent optical properties, is applied for a wide range of integrated optical devices operating at visible or NIR wavelengths. High-quality channel waveguides are reliably fabricated by plasma enhanced chemical vapor deposition and reactive ion etching following standard lithography. Based on a general, polarization-independent channel waveguide layout various arrayed waveguide gratings were designed, realized and tested for on-chip spectrometers in Raman detection and optical coherence ...
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    16. Feature Of The Week 5/29/11: Researchers at University of Twente and University of Amsterdam Investigate Miniaturization of SD-OCT Systems using Integrated Optics

      Feature Of The Week 5/29/11: Researchers at University of Twente and University of Amsterdam Investigate Miniaturization of SD-OCT Systems using Integrated Optics
      Optical coherence tomography (OCT) is an interferometric imaging technique which has developed rapidly over the last 20 years and has many applications in biomedical optics. Current OCT systems consist of a large number of bulk optical components and are quite expensive. Thus integration of optical components is expected to make OCT systems smaller and more cost efficient.Within the MEMPHIS project (Merging Electronics and Micro & Nano-Photonics in Integrated Systems), researchers ...
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  2. About B. Imran Akca

    B. Imran Akca

    B. Imran Akca graduated from Electrical and Electronics Engineering Department of Bilkent University in 2006, Turkey, and received the M.Sc. degree in 2008 from the Institute of Material Science and Nanotechnology in Bilkent University.  She is currently working toward the Ph.D. degree in the area of integrated optics in the Integrated Optical MicroSystems (IOMS) Group at the University of Twente, The Netherlands. Her research interest is designing integrated arrayed waveguide grating spectrometers for optical coherence tomography systems.