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Wang C, Yin Z, He B, Chen Z, Hu Z, Shi Y, Zhang X, Zhang N, Jing L, Wang G, Xue P. Polarization-isolated stretched-pulse mode-locked swept laser for 10.3-MHz A-line rate optical coherence tomography. OPTICS LETTERS 2023; 48:4025-4028. [PMID: 37527109 DOI: 10.1364/ol.495786] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/10/2023] [Indexed: 08/03/2023]
Abstract
Stretched-pulse mode-locked (SPML) lasing based on a chirped fiber Bragg grating (CFBG) has proven to be a powerful method to generate wavelength-swept lasers at speeds of tens of megahertz. However, light transmitted through the CFBG may lead to undesirable laser oscillation that disrupts the mechanism of the laser active mode locking in the theta ring cavity. In this Letter, we demonstrate a simple and low-cost approach to suppress the transmitted light and achieve an effective duty cycle of ∼100% with only one CFBG and no need for intra-cavity semiconductor optical amplifier (SOA) modulation, extra-cavity optical buffering, and post amplification. By utilizing polarization isolation of the bi-directional CFBG, a swept laser centered at 1305 nm, with repetition rate of 10.3 MHz, optical power of 84 mW, and 3 dB bandwidth of 109 nm, is demonstrated. Ultrahigh speed 3D optical coherence tomography (OCT) structural imaging of a human palm in vivo using this swept laser is also demonstrated. We believe that this ultrahigh speed swept laser will greatly promote the OCT technique for industrial and biomedical applications.
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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. NATURE REVIEWS. 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] [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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Joo J, Kim TS, Vakoc BJ, Oh WY. Robust and easy-to-operate stretched-pulse mode-locked wavelength-swept laser with an all-polarization-maintaining fiber cavity for 10 MHz A-line rate optical coherence tomography. OPTICS LETTERS 2021; 46:3857-3860. [PMID: 34388759 PMCID: PMC8455078 DOI: 10.1364/ol.424835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/01/2021] [Indexed: 05/18/2023]
Abstract
We demonstrate robust and easy-to-operate stretched-pulse mode-locked laser (SPML) architectures using all-polarization-maintaining fiber laser cavities. Because of the polarization-maintaining construction, the laser performance is unaffected by mechanical perturbation on the cavity fibers. The lasers automatically initiate linear-in-wavenumber sweeps across 100 nm centered at 1290 nm with a 10 MHz repetition rate. OCT imaging with a sensitivity of 98 dB and a single-sided 6 dB coherence length of 2.5 mm is demonstrated. OCT angiography of a mouse brain that visualized three-dimensional cerebral microvasculature over a field of 1.5mm×1.5mm (398 A-lines × 380 B-scans) at a rate of 5.26 volumes per second is also presented. The robust all-PMF SPML lasers are a turnkey, high-performance source for ultrahigh-speed OCT imaging.
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Affiliation(s)
- JongYoon Joo
- Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
- KI for Health Science and Technology, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
| | - Tae Shik Kim
- Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Benjamin J. Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Wang-Yuhl Oh
- Department of Mechanical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
- KI for Health Science and Technology, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea
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Kim TS, Joo J, Shin I, Shin P, Kang WJ, Vakoc BJ, Oh WY. 9.4 MHz A-line rate optical coherence tomography at 1300 nm using a wavelength-swept laser based on stretched-pulse active mode-locking. Sci Rep 2020; 10:9328. [PMID: 32518256 PMCID: PMC7283258 DOI: 10.1038/s41598-020-66322-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 05/08/2020] [Indexed: 01/07/2023] Open
Abstract
In optical coherence tomography (OCT), high-speed systems based at 1300 nm are among the most broadly used. Here, we present 9.4 MHz A-line rate OCT system at 1300 nm. A wavelength-swept laser based on stretched-pulse active mode locking (SPML) provides a continuous and linear-in-wavenumber sweep from 1240 nm to 1340 nm, and the OCT system using this light source provides a sensitivity of 98 dB and a single-sided 6-dB roll-off depth of 2.5 mm. We present new capabilities of the 9.4 MHz SPML-OCT system in three microscopy applications. First, we demonstrate high quality OCTA imaging at a rate of 1.3 volumes/s. Second, by utilizing its inherent phase stable characteristics, we present wide dynamic range en face Doppler OCT imaging with multiple time intervals ranging from 0.25 ms to 2.0 ms at a rate of 0.53 volumes/s. Third, we demonstrate video-rate 4D microscopic imaging of a beating Xenopus embryo heart at a rate of 30 volumes/s. This high-speed and high-performance OCT system centered at 1300 nm suggests that it can be one of the most promising high-speed OCT platforms enabling a wide range of new scientific research, industrial, and clinical applications at speeds of 10 MHz.
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Affiliation(s)
- Tae Shik Kim
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - JongYoon Joo
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Inho Shin
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Paul Shin
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Woo Jae Kang
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea.,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea
| | - Benjamin J Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
| | - Wang-Yuhl Oh
- Department of Mechanical Engineering, KAIST, Daejeon, Republic of Korea. .,KI for Health Science and Technology, KAIST, Daejeon, Republic of Korea.
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Lindberg R, Laurell F, Fröjdh K, Margulis W. C-cavity fiber laser employing a chirped fiber Bragg grating for electrically gated wavelength tuning. OPTICS EXPRESS 2020; 28:9208-9215. [PMID: 32225532 DOI: 10.1364/oe.383398] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 01/27/2020] [Indexed: 06/10/2023]
Abstract
We present a novel C-cavity concept for tunable lasers. The laser is based on a semiconductor optical amplifier (SOA), serving both as a gain medium as well as a modulator, and a chirped fiber Bragg grating (C-FBG) which acts as the end mirrors on both cavity ends. Driving the SOA with a pulse pair with variable delay enables wavelength tuning by targeting different regions in the C-FBG with the circulating pulse. The cavity design allows for wide tuning while maintaining a constant repetition rate, we show a tuning range of 35 nm -limited by the C-FBG's reflection bandwidth. Time-multiplexed operation with four different wavelengths is also demonstrated. Furthermore, the laser performance and dynamics under different operating conditions are analyzed and discussed.
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Lippok N, Bouma BE, Vakoc BJ. Stable multi-megahertz circular-ranging optical coherence tomography at 1.3 µm. BIOMEDICAL OPTICS EXPRESS 2020; 11:174-185. [PMID: 32010508 PMCID: PMC6968766 DOI: 10.1364/boe.11.000174] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 11/27/2019] [Accepted: 11/29/2019] [Indexed: 05/18/2023]
Abstract
In Fourier-domain optical coherence tomography (OCT), the finite bandwidth of the acquisition electronics constrains the depth range and speed of the system. Circular-ranging (CR) OCT methods use optical-domain compression to surpass this limit. However, the CR-OCT system architectures of prior reports were limited by poor stability and were confined to the 1.55 µm wavelength range. In this work, we describe a novel CR-OCT architecture that is free from these limitations. To ensure stable operation, temperature sensitive optical modules within the system were replaced; the kilometer-length fiber spools used in the stretched-pulse mode-locked (SPML) laser was eliminated in favor of a single 10 meter, continuously chirped fiber Bragg grating, and the interferometer's passive optical quadrature demodulation circuit was replaced by an active technique using a lithium niobate phase modulator. For improved imaging penetration in biological tissues, the system operating wavelength was shifted to a center wavelength of 1.29 µm by leveraging the wavelength flexibility intrinsic to CFBG-based dispersive fibers. These improvements were achieved while maintaining a broad (100 nm) optical bandwidth, a long 4 cm imaging range, and a high 7.6 MHz A-line rate. By enhancing stability, simplifying overall system design, and operating at 1.3 µm, this CR-OCT architecture will allow a broader exploration of CR-OCT in both medical and non-medical applications.
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Affiliation(s)
- Norman Lippok
- Harvard Medical School, Boston, MA 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Brett E. Bouma
- Harvard Medical School, Boston, MA 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Benjamin J. Vakoc
- Harvard Medical School, Boston, MA 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA 02114, USA
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Braaf B, Donner S, Nam AS, Bouma BE, Vakoc BJ. Complex differential variance angiography with noise-bias correction for optical coherence tomography of the retina. BIOMEDICAL OPTICS EXPRESS 2018; 9:486-506. [PMID: 29552388 PMCID: PMC5854053 DOI: 10.1364/boe.9.000486] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/03/2018] [Accepted: 01/03/2018] [Indexed: 05/05/2023]
Abstract
Complex differential variance (CDV) provides phase-sensitive angiographic imaging for optical coherence tomography (OCT) with immunity to phase-instabilities of the imaging system and small-scale axial bulk motion. However, like all angiographic methods, measurement noise can result in erroneous indications of blood flow that confuse the interpretation of angiographic images. In this paper, a modified CDV algorithm that corrects for this noise-bias is presented. This is achieved by normalizing the CDV signal by analytically derived upper and lower limits. The noise-bias corrected CDV algorithm was implemented into an experimental 1 μm wavelength OCT system for retinal imaging that used an eye tracking scanner laser ophthalmoscope at 815 nm for compensation of lateral eye motions. The noise-bias correction improved the CDV imaging of the blood flow in tissue layers with a low signal-to-noise ratio and suppressed false indications of blood flow outside the tissue. In addition, the CDV signal normalization suppressed noise induced by galvanometer scanning errors and small-scale lateral motion. High quality cross-section and motion-corrected en face angiograms of the retina and choroid are presented.
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Affiliation(s)
- Boy Braaf
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Sabine Donner
- Heidelberg Engineering GmbH, Max-Jarecki-Straße 8, 69115 Heidelberg, Germany
| | - Ahhyun S. Nam
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
| | - Brett E. Bouma
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
| | - Benjamin J. Vakoc
- Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom St., Boston, Massachusetts 02114, USA
- Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
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