1. Articles from Myung Yung Jeong

    1-15 of 15
    1. Optical coherence tomography using active mode-locking fiber laser

      Optical coherence tomography using active mode-locking fiber laser

      Discloses is an optical coherence tomography (OCT) which uses an active mode-locking fiber laser in order to obtain image information of a sample. An imaging device in accordance with an embodiment comprises: a light source unit; a light separation unit; a reference unit; a diagnostic unit; a light coupling unit; and a signal processing unit. The imaging device removes a high-priced variable filter which has mechanical restrictions by directly delivering a modulation signal to a light source unit, so it can overcome mechanical restrictions and reduce costs.

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    2. A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

      A Fiber Bragg Grating Sensor Interrogation System Based on a Linearly Wavelength-Swept Thermo-Optic Laser Chip

      A linearized wavelength-swept thermo-optic laser chip was applied to demonstrate a fiber Bragg grating (FBG) sensor interrogation system. A broad tuning range of 11.8 nm was periodically obtained from the laser chip for a sweep rate of 16 Hz. To measure the linear time response of the reflection signal from the FBG sensor, a programmed driving signal was directly applied to the wavelength-swept laser chip. The linear wavelength response of the applied strain was clearly extracted with an R-squared value of 0.99994. To test the feasibility of the system for dynamic measurements, the dynamic strain was successfully interrogated ...

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    3. Short cavity active mode locking fiber laser for optical sensing and imaging

      Short cavity active mode locking fiber laser for optical sensing and imaging

      We demonstrate a highly linear wavenumber- swept active mode locking (AML) fiber laser for optical sensing and imaging without any wavenumber-space resampling process. In this all-electric AML wavenumber-swept mechanism, a conventional wavelength selection filter is eliminated and, instead, the suitable programmed electric modulation signal is directly applied to the gain medium. Various types of wavenumber (or wavelength) tunings can be implemented because of the filter-less cavity configuration. Therefore, we successfully demonstrate a linearly wavenumber-swept AML fiber laser with 26.5 mW of output power to obtain an in-vivo OCT image at the 100 kHz swept rate.

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    4. Simultaneous Dual-Band Wavelength-Swept Fiber Laser Based on Active Mode Locking

      Simultaneous Dual-Band Wavelength-Swept Fiber Laser Based on Active Mode Locking

      We report a simultaneous dual-band wavelength-swept laser based on the active mode locking method. By applying a single modulation signal, synchronized sweeping of two lasing-wavelengths is demonstrated without the use of a mechanical wavelength-selecting filter. Two free spectral ranges are independently controlled with a dual path-length configuration of a laser cavity. The static and dynamic performances of a dual-band wavelength-swept active mode locking fiber laser are characterized in both the time and wavelength regions. Two lasing wavelengths were swept simultaneously from 1263.0 to 1333.3 nm for the 1310 nm band and from 1493 to 1563.3 nm for ...

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    5. Optical Coherence Tomography Using Active MODE-LOCKING Fiber Laser

      Optical Coherence Tomography Using Active MODE-LOCKING Fiber Laser

      Discloses is an optical coherence tomography (OCT) which uses an active mode-locking fiber laser in order to obtain image information of a sample. An imaging device in accordance with an embodiment comprises: a light source unit; a light separation unit; a reference unit; a diagnostic unit; a light coupling unit; and a signal processing unit. The imaging device removes a high-priced variable filter which has mechanical restrictions by directly delivering a modulation signal to a light source unit, so it can overcome mechanical restrictions and reduce costs.

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    6. Spectrally Sampled OCT Imaging Based on 1.7um Continuous-Wave Supercontinuum Source

      Spectrally Sampled OCT Imaging Based on 1.7um Continuous-Wave Supercontinuum Source

      We demonstrate a novel multiwavelength light source around the 1.7um region based on continuous-wave (CW) supercontinuum (SC) generation for the deeper imaging of low-water-absorption sample with a spectrally sampled optical coherence tomography (OCT) system. This self-regulated Gaussian spectrum of CW SC source has an extremely smooth flat width with more than 210-nm full-width at half-maximum bandwidth centered at the 1.7um region, a high output power of 500 mW, and a low temporal instability with less than 0.1 dB for an hour. In order to improve the OCT signal sensitivity without increasing the optical illumination power, a multiwavelength ...

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    7. Optical Coherence Tomography Using Active Mode-Locking Fiber Laser

      Optical Coherence Tomography Using Active Mode-Locking Fiber Laser

      An optical coherence tomography (OCT) uses an active mode-locking fiber laser in order to obtain image information of a sample. An imaging device of the present invention comprises: a light source unit that emits light having a central wavelength which is periodically changed by a modulation signal received from the inside of a resonator; a light separation unit that separates the light having a single path, which is emitted from the light source unit, into a first light and a second light having different paths; a reference unit that is disposed on a path through which the first light separated ...

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    8. Double common-path interferometer for flexible optical probe of optical coherence tomography

      Double common-path interferometer for flexible optical probe of optical coherence tomography

      A flexible curled optical cord is useful for a common-path optical coherence tomography (OCT) system because a bending-insensitive arbitrary length can be chosen for the endoscopic imaging probe. However, there has been a critical problem that the partial reflector needs to be placed in between the sample and the objective lens. It limits the structure design of optical probe and leads to a low transverse resolution OCT imaging. Instead of a conventional single common-path interferometer, we propose a novel double common-path interferometer configuration in order to generate an interference signal that is independent of the optical distance between the partial ...

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    9. Characterization of wavelength-swept active mode locking fiber laser based on reflective semiconductor optical amplifier

      Characterization of wavelength-swept active mode locking fiber laser based on reflective semiconductor optical amplifier

      The static and dynamic characteristics of a wavelength-swept active mode locking (AML) fiber laser are presented in both the time-region and wavelength-region. This paper shows experimentally that the linewidth of a laser spectrum and the bandwidth of the sweeping wavelength are dependent directly on the length and dispersion of the fiber cavity as well as the modulation frequency and sweeping rate under the mode-locking condition. To achieve a narrower linewidth, a longer length and higher dispersion of the fiber cavity as well as a higher order mode locking condition are required simultaneously. For a broader bandwidth, a lower order of ...

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    10. Flexible Curled Optical Cord for Bending-Insensitive Optical Imaging Delivery

      Flexible Curled Optical Cord for Bending-Insensitive Optical Imaging Delivery

      In the application of optical imaging technologies to the biomedical field, the flexible optical cord is one of the key components used to deliver the reflected optical signal from the internal biological tissue to the biomedical imaging system. However, the conventional optical fibers suffer from a critical wiring limitation, which results in severe power losses under a small bending radius that is less than a few centimeters. In this paper, we demonstrate that holey optical fibers with 18 air holes in cladding have negligible bending loss under a minimum bending radius of 3 mm. Excellent bending insensitivity of the holey ...

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    11. Novel wavelength-swept Raman laser for arbitrary gain band OCT

      Novel wavelength-swept Raman laser is newly demonstrated to implement an arbitrary gain band for a swept-source optical coherence tomography (SS-OCT). Instead of conventional semiconductor optical amplifier, we adapt optical fiber Raman amplification, which can easily generate an instant femto-second optical gain at arbitrary wavelength region from 1.1 to 1.6 micrometer using a high-power optical pump power. We also experimentally demonstrate OCT images using the novel wavelength-swept Raman laser source.

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    12. Spectrally-sampled OCT for sensitivity improvement from limited optical power

      Spectrally-sampled OCT for sensitivity improvement from limited optical power

      Although high optical illumination power is favored in optical coherence tomography (OCT) for better signal-to-noise ratio, optical power is often limited by a damaged threshold for biomedical living tissues and autocorrelation signals observed in tomograms. In order to improve signal sensitivity without increasing the optical illumination power, a spectrally sampled multi-wavelength light source is proposed for the OCT system. A fiber Sagnac comb filter was used to spectrally sample the output of a continuous spectral light source. Point spread function analysis shows that the spectrally sampled OCT has an almost 50% dynamic range improvement in comparison with a conventional continuous ...

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    13. Multi-wavelength source for the lower exposure intensity of spectral OCT

      There have been several technologies to enable high resolution cross-sectional images of biological tissues in optical coherence tomography (OCT) method. Optical frequency comb (OFC) source has been proposed to overcome the crosstalk problem among the CCD detector pixels of the continuous spectrum of light source. Recently, a passive-type OFC is demonstrated simply placing a Fabry-Perot interferometer filter right after the broadband light source, but it shows a high loss of output light power and limited tenability of channel spacing of multi-wavelength. In this work, we experimentally demonstrate a spectral comparison of a novel multi-wavelength source based on a fiber Sagnac ...

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    14. Curled optical patch cord for bending insensitive biomedical imaging endoscope

      Biomedical optical imaging technologies based on optical fibers have been of great interest because of their superiority over conventional bulk-optic counter part in size and integration. Flexible endoscope is a key component to deliver the reflected optical signal from biological tissue to the optical imaging system, such as Optical Coherence Tomography (OCT) and Fiber Confocal Microscopy (FCM). However, conventional optical fibers for the biomedical imaging endoscope have been suffered from a critical wiring problem of a fiber waveguide, which induces additional loss severely. In this work, we have shown excellent properties of holey optical fibers with low bending loss under ...

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    15. Endoscopic common-path OCT based on sweeping laser source and curled optical patch cord

      Several technical problems have to be overcome before Optical Coherence Tomography (OCT) can be accepted among the established endoscopic imaging modalities. Most of conventional Michelson-based OCT systems need to have two separated paths of the sample and reference arms, which limits the flexibility of endoscopic probe. Recently, common-path interferometer based OCT have been demonstrated to circumvent the mismatch problems of length, polarization, and dispersion between the reference and sample arms, but the interferometric scanning methods have been realized with time-domain PZT or spectral-domain CCD. In this work, we demonstrate a novel Fourier-domain common-path OCT based on sweeping laser source, which ...

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    1-15 of 15
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  2. Topics in the News

    1. (15 articles) Pusan National University
    2. (15 articles) Myung Yung Jeong
    3. (13 articles) Chang-Seok Kim
    4. (6 articles) Hwi Don Lee
    5. (6 articles) Jae-Seok Park
    6. (3 articles) Tae Joong Eom
    7. (2 articles) UC Irvine
    8. (2 articles) Gwangju Institute of Science and Technology
    9. (2 articles) Zhongping Chen
    10. (1 articles) Johns Hopkins University
    11. (1 articles) UCLA
    12. (1 articles) University of Groningen
    13. (1 articles) University of Wisconsin
    14. (1 articles) University of St. Andrews
    15. (1 articles) Duke University
    16. (1 articles) Kishan Dholakia
    17. (1 articles) Cynthia A. Toth
    18. (1 articles) Optovue
    19. (1 articles) Leica
    20. (1 articles) Heidelberg Engineering
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    Spectrally-sampled OCT for sensitivity improvement from limited optical power Flexible Curled Optical Cord for Bending-Insensitive Optical Imaging Delivery Characterization of wavelength-swept active mode locking fiber laser based on reflective semiconductor optical amplifier Double common-path interferometer for flexible optical probe of optical coherence tomography Spectrally Sampled OCT Imaging Based on 1.7um Continuous-Wave Supercontinuum Source Short cavity active mode locking fiber laser for optical sensing and imaging Long-Term Arterial Remodeling After Bioresorbable Scaffold Implantation 4-Year Follow-up of Quantitative Coronary Angiography, Histology and Optical Coherence Tomography Visualization of Bacterial Colonization and Cellular Layers in a Gut-on-a-Chip System Using Optical Coherence Tomography Optical Coherence Tomography Measurements as Potential Imaging Biomarkers for Parkinson's Disease: A Systematic Review and Meta-analysis Use of ultra-wide field retinal imaging and optical coherence tomography angiography in the diagnosis of incomplete Susac syndrome Repeatability and agreement of total corneal and sublayer pachymetry with two different algorithms of fourier-domain optical coherence tomography in myopic and post photorefractive keratectomy eyes Monitoring Response to Platelet-Rich Plasma in Patients with Alopecia Areata with Optical Coherence Tomography: A Case Series