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Lee GH, Ahn S, Kim MS, Lee SW, Kim JS, Choi BK, Pagidi S, Jeon MY. Output Characterization of 220 nm Broadband 1250 nm Wavelength-Swept Laser for Dynamic Optical Fiber Sensors. Sensors (Basel) 2022; 22:8867. [PMID: 36433461 PMCID: PMC9696297 DOI: 10.3390/s22228867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Broadband wavelength-swept lasers (WSLs) are widely used as light sources in biophotonics and optical fiber sensors. Herein, we present a polygonal mirror scanning wavelength filter (PMSWF)-based broadband WSL using two semiconductor optical amplifiers (SOAs) with different center wavelengths as the gain medium. The 10-dB bandwidth of the wavelength scanning range with 3.6 kHz scanning frequency was approximately 223 nm, from 1129 nm to 1352 nm. When the scanning frequency of the WSL was increased, the intensity and bandwidth decreased. The main reason for this is that the laser oscillation time becomes insufficient as the scanning frequency increases. We analyzed the intensity and bandwidth decrease according to the increase in the scanning frequency in the WSL through the concept of saturation limit frequency. In addition, optical alignment is important for realizing broadband WSLs. The optimal condition can be determined by analyzing the beam alignment according to the position of the diffraction grating and the lenses in the PMSWF. This broadband WSL is specially expected to be used as a light source in broadband distributed dynamic FBG fiber-optic sensors.
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Affiliation(s)
- Gi Hyen Lee
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Soyeon Ahn
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Min Su Kim
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Sang Won Lee
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Ji Su Kim
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Byeong Kwon Choi
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Srinivas Pagidi
- Institute of Quantum Systems (IQS), Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
| | - Min Yong Jeon
- Department of Physics, College of Natural Sciences, Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
- Institute of Quantum Systems (IQS), Chungnam National University, 99 Daehak-ro, Yuseong-gu, Daejeon 34134, Republic of Korea
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Bouma B, de Boer J, Huang D, Jang I, Yonetsu T, Leggett C, Leitgeb R, Sampson D, Suter M, Vakoc B, Villiger M, Wojtkowski M. Optical coherence tomography. Nat Rev Methods Primers 2022; 2:79. [PMID: 36751306 PMCID: PMC9901537 DOI: 10.1038/s43586-022-00162-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Optical coherence tomography (OCT) is a non-contact method for imaging the topological and internal microstructure of samples in three dimensions. OCT can be configured as a conventional microscope, as an ophthalmic scanner, or using endoscopes and small diameter catheters for accessing internal biological organs. In this Primer, we describe the principles underpinning the different instrument configurations that are tailored to distinct imaging applications and explain the origin of signal, based on light scattering and propagation. Although OCT has been used for imaging inanimate objects, we focus our discussion on biological and medical imaging. We examine the signal processing methods and algorithms that make OCT exquisitely sensitive to reflections as weak as just a few photons and that reveal functional information in addition to structure. Image processing, display and interpretation, which are all critical for effective biomedical imaging, are discussed in the context of specific applications. Finally, we consider image artifacts and limitations that commonly arise and reflect on future advances and opportunities.
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Affiliation(s)
- B.E. Bouma
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA,Institute for Medical Engineering and Physics, Massachusetts Institute of Technology, Cambridge, MA, USA,Harvard Medical School, Boston, MA, USA,Corresponding author:
| | - J.F. de Boer
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - D. Huang
- Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - I.K. Jang
- Harvard Medical School, Boston, MA, USA,Cardiology Division, Massachusetts General Hospital, Boston, MA, USA
| | - T. Yonetsu
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - C.L. Leggett
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA
| | - R. Leitgeb
- Institute of Medical Physics, University of Vienna, Wien, Austria
| | - D.D. Sampson
- School of Physics and School of Biosciences and Medicine, University of Surrey, Guildford, United Kingdom
| | - M. Suter
- Harvard Medical School, Boston, MA, USA,Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital, Boston, MA, USA
| | - B. Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA,Harvard Medical School, Boston, MA, USA
| | - M. Villiger
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA,Harvard Medical School, Boston, MA, USA
| | - M. Wojtkowski
- Institute of Physical Chemistry and International Center for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland,Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
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Lee GH, Ahn S, Gene J, Jeon MY. 1.1-µm Band Extended Wide-Bandwidth Wavelength-Swept Laser Based on Polygonal Scanning Wavelength Filter. Sensors (Basel) 2021; 21:3053. [PMID: 33925592 DOI: 10.3390/s21093053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 12/03/2022]
Abstract
We demonstrated a 1.1-µm band extended wideband wavelength-swept laser (WSL) that combined two semiconductor optical amplifiers (SOAs) based on a polygonal scanning wavelength filter. The center wavelengths of the two SOAs were 1020 nm and 1140 nm, respectively. Two SOAs were connected in parallel in the form of a Mach-Zehnder interferometer. At a scanning speed of 1.8 kHz, the 10-dB bandwidth of the spectral output and the average power were approximately 228 nm and 16.88 mW, respectively. Owing to the nonlinear effect of the SOA, a decrease was observed in the bandwidth according to the scanning speed. Moreover, the intensity of the WSL decreased because the oscillation time was smaller than the buildup time. In addition, a cholesteric liquid crystal (CLC) cell was fabricated as an application of WSL, and the dynamic change of the first-order reflection of the CLC cell in the 1-µm band was observed using the WSL. The pitch jumps of the reflection band occurred according to the electric field applied to the CLC cell, and instantaneous changes were observed.
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Jeong D, Park SJ, Jang H, Kim H, Kim J, Kim CS. Swept-Source-Based Chromatic Confocal Microscopy. Sensors (Basel) 2020; 20:s20247347. [PMID: 33371378 PMCID: PMC7767395 DOI: 10.3390/s20247347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/15/2020] [Accepted: 12/18/2020] [Indexed: 06/12/2023]
Abstract
Chromatic confocal microscopy (CCM) has been intensively developed because it can exhibit effective focal position scanning based on the axial chromatic aberration of broadband light reflected from a target. To improve the imaging speed of three-dimensional (3D) surface profiling, we have proposed the novel concept of swept-source-based CCM (SS-CCM) and investigated the usefulness of the corresponding imaging system. Compared to conventional CCM based on a broadband light source and a spectrometer, a swept-source in the proposed SS-CCM generates light with a narrower linewidth for higher intensity, and a single photodetector employed in the system exhibits a fast and sensitive response by immediately obtaining spectrally encoded depth from a chromatic dispersive lens array. Results of the experiments conducted to test the proposed SS-CCM system indicate that the system exhibits an axial chromatic focal distance range of approximately 360 μm for the 770-820 nm swept wavelength range. Moreover, high-speed surface profiling images of a cover glass and coin were successfully obtained with a short measurement time of 5 ms at a single position.
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Affiliation(s)
- Dawoon Jeong
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Korea; (D.J.); (S.J.P.); (H.J.)
| | - Se Jin Park
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Korea; (D.J.); (S.J.P.); (H.J.)
| | - Hansol Jang
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Korea; (D.J.); (S.J.P.); (H.J.)
| | - Hyunjoo Kim
- Taihan Fiber Optics Co., Ltd., Ansan-si 15601, Gyeonggi-do, Korea; (H.K.); (J.K.)
| | - Jaesun Kim
- Taihan Fiber Optics Co., Ltd., Ansan-si 15601, Gyeonggi-do, Korea; (H.K.); (J.K.)
| | - Chang-Seok Kim
- Department of Cogno-Mechatronics Engineering, Pusan National University, Busan 46241, Korea; (D.J.); (S.J.P.); (H.J.)
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Ahn S, Ko MO, Kim JH, Chen Z, Jeon MY. Characterization of Second-Order Reflection Bands from a Cholesteric Liquid Crystal Cell Based on a Wavelength-Swept Laser. Sensors (Basel) 2020; 20:s20164643. [PMID: 32824725 PMCID: PMC7472269 DOI: 10.3390/s20164643] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/12/2020] [Accepted: 08/15/2020] [Indexed: 11/16/2022]
Abstract
We report the results of an experimental study of the characterization of second-order reflection bands from a cholesteric liquid crystal (CLC) cell that depends on the applied electric field, using a wide bandwidth wavelength-swept laser. The second-order reflection bands around 1300 nm and 1500 nm were observed using an optical spectrum analyzer when an electric field was applied to a horizontally oriented electrode cell with a pitch of 1.77 μm. A second-order reflection spectrum began to appear when the intensity of the electric field was 1.03 Vrms/μm with the angle of incidence to the CLC cell fixed at 36°. The reflectance increased as the intensity of the electric field increased at an angle of incidence of 20°, whereas at an incident angle of 36°, when an electric field of a predetermined value or more was applied to the CLC cell, it was confirmed that deformation was completely formed in the liquid crystal and the reflectance was saturated to a constant level. As the intensity of the electric field increased further, the reflection band shifted to a longer wavelength and discontinuous wavelength shift due to the pitch jump was observed rather than a continuous wavelength increase. In addition, the reflection band changed when the angle of incidence on the CLC cell was changed. As the angle of incidence gradually increased, the center wavelength of the reflection band moved towards shorter wavelengths. In the future, we intend to develop a device for optical wavelength filters based on side-polished optical fibers. This is expected to have a potential application as a wavelength notch filter or a bandpass filter.
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Affiliation(s)
- Soyeon Ahn
- Department of Physics, Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea; (S.A.); (J.-H.K.)
| | - Myeong Ock Ko
- Core Technology R&D Team, Samsung Electronics, Hwaseong-si, Gyeonggi-do 18448, Korea;
| | - Jong-Hyun Kim
- Department of Physics, Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea; (S.A.); (J.-H.K.)
- Instituted of Quantum Systems (IQS), Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea
| | - Zhongping Chen
- Beckman Laser Institute, UC Irvine, Irvine, CA 92612, USA;
| | - Min Yong Jeon
- Department of Physics, Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea; (S.A.); (J.-H.K.)
- Instituted of Quantum Systems (IQS), Chungnam National University, 99 Daehak-ro Yuseong-gu, Daejeon 34134, Korea
- Correspondence: ; Tel.: +82-42-821-5459
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Kim JW, Jang H, Kim GH, Jun SW, Kim CS. Multi-spectral laser speckle contrast images using a wavelength-swept laser. J Biomed Opt 2019; 24:1-9. [PMID: 31290292 PMCID: PMC6995959 DOI: 10.1117/1.jbo.24.7.076001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 06/06/2019] [Indexed: 06/09/2023]
Abstract
A multi-spectral laser speckle contrast imaging (MS-LSCI) system is proposed using only a single wavelength-swept laser, which provides both highly coherent and multi-spectral outputs to simultaneously generate laser speckle contrast images and multi-spectral images, respectively. Using a laser light swept from 770 to 821 nm at a repetition rate of 5 Hz and a CCD camera of 335 fps, 67 multi-spectral frame images are acquired in 0.76 nm wavebands over 51 nm spectral range. The spectral sub-windowing method of single wavelength-swept laser source is used to solve the lack of spectral information from a few individual light sources, which is a limitation of conventional MS-LSCI systems. In addition to the speckle flow index from the LSCI frames, the multi-spectrally encoded images can generate additional images of spectral absorbance. To further examine the performance of the MS-LSCI system, an in vivo cuff-induced ischemia experiment was conducted to show the real-time imaging of hemodynamic and blood oxygen saturation changes simultaneously over the entire 2.5 cm × 4.5 cm field of view.
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Affiliation(s)
- Jeong Won Kim
- Pusan National University, Department of Cogno-Mechatronics Engineering, Busan, Republic of Korea
| | - Hansol Jang
- Pusan National University, Department of Cogno-Mechatronics Engineering, Busan, Republic of Korea
| | - Gyeong Hun Kim
- Pusan National University, Department of Cogno-Mechatronics Engineering, Busan, Republic of Korea
| | - Seung Won Jun
- Pusan National University, Department of Cogno-Mechatronics Engineering, Busan, Republic of Korea
| | - Chang-Seok Kim
- Pusan National University, Department of Cogno-Mechatronics Engineering, Busan, Republic of Korea
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Kwon YS, Ko MO, Jung MS, Park IG, Kim N, Han SP, Ryu HC, Park KH, Jeon MY. Dynamic sensor interrogation using wavelength-swept laser with a polygon-scanner-based wavelength filter. Sensors (Basel) 2013; 13:9669-78. [PMID: 23899934 PMCID: PMC3812574 DOI: 10.3390/s130809669] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/30/2013] [Accepted: 07/15/2013] [Indexed: 11/20/2022]
Abstract
We report a high-speed (~2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement.
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Affiliation(s)
- Yong Seok Kwon
- Department of Physics, Chungnam National University, Daejeon 305-764, Korea; E-Mails: (Y.S.K.); (M.O.K.); (M.S.J.); (I.G.P.)
| | - Myeong Ock Ko
- Department of Physics, Chungnam National University, Daejeon 305-764, Korea; E-Mails: (Y.S.K.); (M.O.K.); (M.S.J.); (I.G.P.)
| | - Mi Sun Jung
- Department of Physics, Chungnam National University, Daejeon 305-764, Korea; E-Mails: (Y.S.K.); (M.O.K.); (M.S.J.); (I.G.P.)
| | - Ik Gon Park
- Department of Physics, Chungnam National University, Daejeon 305-764, Korea; E-Mails: (Y.S.K.); (M.O.K.); (M.S.J.); (I.G.P.)
| | - Namje Kim
- THz Photonics Creative Research Center, ETRI, Daejeon 305-700, Korea; E-Mails: (N.K.); (S.-P.H.); (K.H.P.)
| | - Sang-Pil Han
- THz Photonics Creative Research Center, ETRI, Daejeon 305-700, Korea; E-Mails: (N.K.); (S.-P.H.); (K.H.P.)
| | - Han-Cheol Ryu
- Department of Car-Mechatronics, Sahmyook University, Seoul 139-742, Korea; E-Mail:
| | - Kyung Hyun Park
- THz Photonics Creative Research Center, ETRI, Daejeon 305-700, Korea; E-Mails: (N.K.); (S.-P.H.); (K.H.P.)
| | - Min Yong Jeon
- Department of Physics, Chungnam National University, Daejeon 305-764, Korea; E-Mails: (Y.S.K.); (M.O.K.); (M.S.J.); (I.G.P.)
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +82-42-821-5459; Fax: +82-42-822-8011
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Lee HD, Jung EJ, Jeong MY, Chen Z, Kim CS. Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer. Meas Sci Technol 2013; 24:65101. [PMID: 24489440 PMCID: PMC3904393 DOI: 10.1088/0957-0233/24/6/065101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated non-uniform wavelength-spacing response in demodulating the time-encoded parameter to the absolute wavelength. In this work, the calibration signal from a polarization-maintaining fiber Sagnac interferometer shares the FDML wavelength-swept laser for FBG sensors to convert the time-encoded FBG signal to the wavelength-encoded uniform-spacing signal.
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Affiliation(s)
- Hwi Don Lee
- Department of Cogno-Mechatronics Engineering, World Class University Program, Pusan National University, Busan, 609-735, Korea
| | - Eun Joo Jung
- Nano-Photonics Research Center, Korea Photonics Technology Institute, Gwangju 500-779, Korea
| | - Myung Yung Jeong
- Department of Cogno-Mechatronics Engineering, World Class University Program, Pusan National University, Busan, 609-735, Korea
| | - Zhongping Chen
- Department of Cogno-Mechatronics Engineering, World Class University Program, Pusan National University, Busan, 609-735, Korea
- Beckman Laser Institute, Department of Biomedical Engineering, University of California, Irvine, CA 92612, USA
| | - Chang-Seok Kim
- Department of Cogno-Mechatronics Engineering, World Class University Program, Pusan National University, Busan, 609-735, Korea
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