1
|
Chen H, Li Y, Huang D, Shi Y, Li F, Lu C, Wai PKA. Highly coherent, flat, and broadband time-stretched swept source based on extra-cavity spectral shaping assisted by a booster semiconductor optical amplifier. OPTICS EXPRESS 2022; 30:33708-33720. [PMID: 36242399 DOI: 10.1364/oe.468042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 08/08/2022] [Indexed: 06/16/2023]
Abstract
We demonstrate a flat broadband time-stretched swept source based on extra-cavity spectral shaping. By adjusting the polarization-dependent gain profile and driving current of the booster optical amplifier (BOA), extra-cavity spectral shaping is optimized to generate output with a 1-dB bandwidth of ∼100 nm, 3-dB bandwidth of ∼140 nm and output power of ∼21.4 mW. The short-term and long-term stabilities are characterized. The average cross correlation of 183,485 round trips is 0.9997 with a standard deviation of 2×10-5, indicating high single-shot spectral similarity and high coherence. The noise floor of relative spectral energy jitter is -141.7 dB/Hz, indicating a high short-term spectral energy stability. The proposed highly stable flat broadband time-stretched swept source is applied to an optical coherence tomography (OCT) system. The axial resolution is 10.8 µm. The proposed swept source can serve as excellent light sources in ultra-fast coherent detection systems for high precision sensing and imaging.
Collapse
|
2
|
Zhao Z, Jin L, Set SY, Yamashita S. Broadband similariton generation in a mode-locked Yb-doped fiber laser. OPTICS LETTERS 2022; 47:2238-2241. [PMID: 35486769 DOI: 10.1364/ol.456808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/05/2022] [Indexed: 06/14/2023]
Abstract
We experimentally demonstrated a broadband similariton generated from a mode-locked Yb-doped fiber laser with dispersion compensation. The broadest spectrum was obtained by pushing the net dispersion to its limitation and fully exploiting the gain bandwidth. The spectrum was 115 nm broad in 10 dB bandwidth and 36 nm broad in 3 dB bandwidth. The output was 105 mW optical power at 545 mW pump power. Simulation combined with experiment was performed to investigate and confirm the mode-locking regime of the laser. Experimental observations agreed well with the numerical simulation. We believe our study provides a practical route for designing broadband mode-locked fiber lasers.
Collapse
|
3
|
Ling L, Lin W, Wang W, Liang Z, Chen X, Guo Y, Wei X, Yang Z. Threshold reduction of GHz-repetition-rate passive mode-locking by tapering the gain fiber. OPTICS EXPRESS 2022; 30:13095-13105. [PMID: 35472931 DOI: 10.1364/oe.451406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 03/27/2022] [Indexed: 06/14/2023]
Abstract
Passively mode-locked fiber lasers with GHz repetition rates have recently attracted significant attention in frontier research areas, including frequency-comb spectroscopy, coherent optical communication, photonic radar, micromachining, etc. In general, the threshold of passive mode-locking increases with the fundamental repetition rate, which is inversely proportional to the cavity length, and this sets a limit on the scalability of the fundamental repetition rate. To overcome this issue, here we propose to reduce the threshold of continuous-wave mode-locking (CWML) by precisely tapering the gain fiber, which can enhance the power density incident on the semiconductor saturable absorber mirror. Assisted by the analysis of guiding property, an experimental scheme is established for tapering standard Yb-doped fibers (125 µm cladding diameter), and tapered Yb-doped fibers with different waist diameters can be fabricated. Using a tapered Yb-doped gain fiber with waist cladding diameter of 90 µm, we are able to achieve CWML with a fundamental repetition rate of 3.3 GHz, and reduce its mode-locking threshold by 31%. More importantly, the optical spectrum of the CWML is found to be broadened with the waist diameter reduction of the gain fiber, which is beneficial for generating shorter transform-limited pulses. The efforts made in this work can provide a promising route to realize stable high-repetition-rate mode-locked fiber lasers with moderate levels of pump power.
Collapse
|
4
|
Zhang J, Nguyen T, Potsaid B, Jayaraman V, Burgner C, Chen S, Li J, Liang K, Cable A, Traverso G, Mashimo H, Fujimoto JG. Multi-MHz MEMS-VCSEL swept-source optical coherence tomography for endoscopic structural and angiographic imaging with miniaturized brushless motor probes. BIOMEDICAL OPTICS EXPRESS 2021; 12:2384-2403. [PMID: 33996236 PMCID: PMC8086463 DOI: 10.1364/boe.420394] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 05/02/2023]
Abstract
Swept source optical coherence tomography (SS-OCT) enables volumetric imaging of subsurface structure. However, applications requiring wide fields of view (FOV), rapid imaging, and higher resolutions have been challenging because multi-MHz axial scan (A-scan) rates are needed. We describe a microelectromechanical systems vertical cavity surface-emitting laser (MEMS-VCSEL) SS-OCT technology for A-scan rates of 2.4 and 3.0 MHz. Sweep to sweep calibration and resampling are performed using dual channel acquisition of the OCT signal and a Mach Zehnder interferometer signal, overcoming inherent optical clock limitations and enabling higher performance. We demonstrate ultrahigh speed structural SS-OCT and OCT angiography (OCTA) imaging of the swine gastrointestinal tract using a suite of miniaturized brushless motor probes, including a 3.2 mm diameter micromotor OCT catheter, a 12 mm diameter tethered OCT capsule, and a 12 mm diameter widefield OCTA probe. MEMS-VCSELs promise to enable ultrahigh speed SS-OCT with a scalable, low cost, and manufacturable technology, suitable for a diverse range of imaging applications.
Collapse
Affiliation(s)
- Jason Zhang
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- These authors contributed equally to this work
| | - Tan Nguyen
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- These authors contributed equally to this work
| | - Benjamin Potsaid
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Advanced Imaging Group, Thorlabs Inc., Newton, NJ 07860, USA
| | | | | | - Siyu Chen
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jinxi Li
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Kaicheng Liang
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alex Cable
- Advanced Imaging Group, Thorlabs Inc., Newton, NJ 07860, USA
| | - Giovanni Traverso
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Division of Gastroenterology, Massachusetts General Hospital, Boston, MA 02114, USA
- Division of Gastroenterology, Brigham and Women’s Hospital, Boston, MA 02115, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Hiroshi Mashimo
- Harvard Medical School, Boston, MA 02115, USA
- Veterans Affairs Boston Healthcare System, Boston, MA 02132, USA
| | - James G. Fujimoto
- Department of Electrical Engineering and Computer Science, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| |
Collapse
|
5
|
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.
Collapse
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.
| |
Collapse
|
6
|
Kong C, Pilger C, Hachmeister H, Wei X, Cheung TH, Lai CSW, Lee NP, Tsia KK, Wong KKY, Huser T. High-contrast, fast chemical imaging by coherent Raman scattering using a self-synchronized two-colour fibre laser. LIGHT, SCIENCE & APPLICATIONS 2020; 9:25. [PMID: 32133128 PMCID: PMC7039946 DOI: 10.1038/s41377-020-0259-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 01/23/2020] [Accepted: 02/09/2020] [Indexed: 05/11/2023]
Abstract
Coherent Raman scattering (CRS) microscopy is widely recognized as a powerful tool for tackling biomedical problems based on its chemically specific label-free contrast, high spatial and spectral resolution, and high sensitivity. However, the clinical translation of CRS imaging technologies has long been hindered by traditional solid-state lasers with environmentally sensitive operations and large footprints. Ultrafast fibre lasers can potentially overcome these shortcomings but have not yet been fully exploited for CRS imaging, as previous implementations have suffered from high intensity noise, a narrow tuning range and low power, resulting in low image qualities and slow imaging speeds. Here, we present a novel high-power self-synchronized two-colour pulsed fibre laser that achieves excellent performance in terms of intensity stability (improved by 50 dB), timing jitter (24.3 fs), average power fluctuation (<0.5%), modulation depth (>20 dB) and pulse width variation (<1.8%) over an extended wavenumber range (2700-3550 cm-1). The versatility of the laser source enables, for the first time, high-contrast, fast CRS imaging without complicated noise reduction via balanced detection schemes. These capabilities are demonstrated in this work by imaging a wide range of species such as living human cells and mouse arterial tissues and performing multimodal nonlinear imaging of mouse tail, kidney and brain tissue sections by utilizing second-harmonic generation and two-photon excited fluorescence, which provides multiple optical contrast mechanisms simultaneously and maximizes the gathered information content for biological visualization and medical diagnosis. This work also establishes a general scenario for remodelling existing lasers into synchronized two-colour lasers and thus promotes a wider popularization and application of CRS imaging technologies.
Collapse
Affiliation(s)
- Cihang Kong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Biomolecular Photonics, Department of Physics, University of Bielefeld, Universitätsstr, 25, 33615 Bielefeld, Germany
| | - Christian Pilger
- Biomolecular Photonics, Department of Physics, University of Bielefeld, Universitätsstr, 25, 33615 Bielefeld, Germany
| | - Henning Hachmeister
- Biomolecular Photonics, Department of Physics, University of Bielefeld, Universitätsstr, 25, 33615 Bielefeld, Germany
| | - Xiaoming Wei
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
- Present Address: Division of Engineering and Applied Science, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 USA
| | - Tom H. Cheung
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Cora S. W. Lai
- Department of Physiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Nikki P. Lee
- Department of Surgery, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kevin. K. Tsia
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kenneth K. Y. Wong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Thomas Huser
- Biomolecular Photonics, Department of Physics, University of Bielefeld, Universitätsstr, 25, 33615 Bielefeld, Germany
| |
Collapse
|
7
|
Duan Y, Dong X, Zhang L, Li Y, Lei Z, Chen L, Zhou X, Zhang C, Zhang X. Ultrafast discrete swept source based on dual chirped combs for microscopic imaging. OPTICS EXPRESS 2019; 27:2621-2631. [PMID: 30732297 DOI: 10.1364/oe.27.002621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 12/27/2018] [Indexed: 06/09/2023]
Abstract
An inertial-free, ultrafast frequency comb source based on two chirped optical frequency combs (OFCs) is proposed and experimentally demonstrated. The high linearity frequency sweeping is realized by the Vernier effect between the two OFCs rather than any mechanical motion component, so that good stability and reliability are ensured and no recalibration or resampling process is required. Swept rate up to 1 MHz is realized while keeping a narrow instantaneous linewidth of 0.03 nm, thanks to the extra-cavity frequency sweeping method. The wavelength step is proportional to the swept rate (3.8 pm at 10 kHz), and can be tuned by changing the repetition rate difference between the two OFCs. This swept source is applied for high-speed wavelength encoded imaging and achieves 4.4-μm spatial resolution at a 329-kHz frame rate. Compared with the traditional time-stretch microscopy, the signal acquisition bandwidth decreased from 3.8 GHz to below 90 MHz to achieve the same spatial resolution. Furthermore, the exposure time for a specific wavelength is much longer due to the discrete sweeping feature, which is a benefit for higher sensitivity. This discrete swept source provided a promising low-cost option for high-speed biomedical imaging systems and high-accuracy spectroscopy.
Collapse
|
8
|
Yang L, Wang S, Kang J, Feng P, Zhang C, Li B, Wong KKY. Sensitivity-enhanced ultrafast optical tomography by parametric- and Raman-amplified temporal imaging. OPTICS LETTERS 2018; 43:5673-5676. [PMID: 30439925 DOI: 10.1364/ol.43.005673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 10/28/2018] [Indexed: 06/09/2023]
Abstract
To overcome the speed limitation of conventional optical tomography, a temporal imaging technique has been integrated with optical time-domain reflectometry to realize ultrafast temporally magnified (TM) tomography. In this Letter, the sensitivity of TM tomography has been further enhanced using optical parametric amplification and distributed Raman amplification, and this technique is named temporally encoded amplified and magnified (TEAM) tomography. As a result, a 78-dB sensitivity has been realized, comparable to ultrafast optical coherence tomography systems. In addition, an 86.7-μm axial resolution can be realized across a 67.5-mm imaging range. To demonstrate the significance of sensitivity improvement, tomographic imaging of a centimeter-thick phantom is provided at an A-scan rate of 44 MHz.
Collapse
|
9
|
Lei C, Kobayashi H, Wu Y, Li M, Isozaki A, Yasumoto A, Mikami H, Ito T, Nitta N, Sugimura T, Yamada M, Yatomi Y, Di Carlo D, Ozeki Y, Goda K. High-throughput imaging flow cytometry by optofluidic time-stretch microscopy. Nat Protoc 2018; 13:1603-1631. [DOI: 10.1038/s41596-018-0008-7] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
10
|
Peng D, Zhang Z, Zeng Z, Zhang L, Lyu Y, Liu Y, Xie K. Single-shot photonic time-stretch digitizer using a dissipative soliton-based passively mode-locked fiber laser. OPTICS EXPRESS 2018; 26:6519-6531. [PMID: 29609340 DOI: 10.1364/oe.26.006519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/02/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate a single-shot photonic time-stretch digitizer using a dissipative soliton-based passively mode-locked fiber laser. The theoretical analysis and simulation results indicate that the dissipative soliton-based optical source with a flat spectrum relieves the envelope-induced signal distortion, and its high energy spectral density helps to improve the signal-to-noise ratio, both of which are favorable for simplifying the optical front-end architecture of a photonic time-stretch digitizer. By employing a homemade dissipative soliton-based passively mode-locked erbium-doped fiber laser in a single-shot photonic time-stretch digitizer, an effective number of bits of 4.11 bits under an effective sampling rate of 100 GS/s is experimentally obtained without optical amplification in the link and pulse envelope removing process.
Collapse
|
11
|
Tozburun S, Blatter C, Siddiqui M, Meijer EFJ, Vakoc BJ. Phase-stable Doppler OCT at 19 MHz using a stretched-pulse mode-locked laser. BIOMEDICAL OPTICS EXPRESS 2018; 9:952-961. [PMID: 29541496 PMCID: PMC5846541 DOI: 10.1364/boe.9.000952] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 12/13/2017] [Accepted: 12/13/2017] [Indexed: 05/18/2023]
Abstract
We present a swept-wavelength optical coherence tomography (OCT) system with a 19 MHz laser source and electronic phase-locking of the source, acquisition clock, and beam scanning mirrors. The laser is based on stretched-pulse active mode-locking using an electro-optic modulator. Beam scanning in the fast axis uses a resonant micro-electromechanical systems (MEMS) -based mirror at ~23.8 kHz. Acquisition is performed at 1.78 Gigasamples per second using an external fixed clock. Phase sensitive imaging without need for k-clocking, A-line triggers, or phase-calibration methods is demonstrated. The system was used to demonstrate inter-frame and inter-volume Doppler imaging in the mouse ear and brain at 4D acquisition rates of 1, 30, 60 and 100 volumes/sec (V-scans/s). Angiography based on inter-frame and inter-volume methods are presented. The platform offers extremely fast and phase-stable measurements that can be used in preclinical angiographic and Doppler investigations of perfusion dynamics.
Collapse
Affiliation(s)
- Serhat Tozburun
- Harvard Medical School, Boston, Massachusetts 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Izmir International Biomedicine and Genome Institute, Dokuz Eylul University, 35340 Balcova, Izmir, Turkey
| | - Cedric Blatter
- Harvard Medical School, Boston, Massachusetts 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Meena Siddiqui
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
| | - Eelco F. J. Meijer
- Harvard Medical School, Boston, Massachusetts 02115, USA
- Edwin L. Steele Laboratory for Tumor Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
| | - Benjamin J. Vakoc
- Harvard Medical School, Boston, Massachusetts 02115, USA
- Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, Massachusetts 02139, USA
| |
Collapse
|
12
|
Sun J, Zhou Y, Dai Y, Li J, Yin F, Dai J, Xu K. All-fiber polarization-maintaining erbium-doped dispersion-managed fiber laser based on a nonlinear amplifying loop mirror. APPLIED OPTICS 2018; 57:1492-1496. [PMID: 29469854 DOI: 10.1364/ao.57.001492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 01/16/2018] [Indexed: 06/08/2023]
Abstract
In this paper, we build a mode-locked all-polarization-maintaining figure-of-8 erbium-doped fiber oscillator based on a nonlinear amplifying loop mirror. The fiber oscillator can generate 1.6 ps chirped pulses that can be de-chirped to 500 fs at 1550 nm with a pulse energy of 0.8 nJ and a repetition rate of 12 MHz. It can be further amplified up to 10 nJ and compressed down to 100 fs with a pre-chirp managed nonlinear amplification setup. Such an oscillator and amplifier configuration has the advantages of self-starting and long-term operation, and it is highly suitable for subsequent frequency conversion, which is desirable for many applications in ultrafast microscopy and precision spectroscopy.
Collapse
|
13
|
Kang J, Feng P, Wei X, Lam EY, Tsia KK, Wong KKY. 102-nm, 44.5-MHz inertial-free swept source by mode-locked fiber laser and time stretch technique for optical coherence tomography. OPTICS EXPRESS 2018; 26:4370-4381. [PMID: 29475287 DOI: 10.1364/oe.26.004370] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
A swept source with both high repetition-rate and broad bandwidth is indispensable to enable optical coherence tomography (OCT) with high imaging rate and high axial resolution. However, available swept sources are commonly either limited in speed (sub-MHz) by inertial or kinetic component, or limited in bandwidth (<100 nm) by the gain medium. Here we report an ultrafast broadband (over 100 nm centered at 1.55-µm) all-fiber inertial-free swept source built upon a high-power dispersion-managed fiber laser in conjunction with an optical time-stretch module which bypasses complex optical amplification scheme, which result in a portable and compact implementation of time-stretch OCT (TS-OCT) at A-scan rate of 44.5-MHz, axial resolution of 14 µm in air (or 10 µm in tissue), and flat sensitivity roll-off within 4.3 mm imaging range. Together with the demonstration of two- and three-dimensional OCT imaging of a mud-fish eye anterior segment, we also perform comprehensive studies on the imaging depth, receiver bandwidth, and group velocity dispersion condition. This all-fiber inertia-free swept source could provide a promising source solution for SS-OCT system to realize high-performance volumetric OCT imaging in real time.
Collapse
|
14
|
Tang AHL, Lai QTK, Chung BMF, Lee KCM, Mok ATY, Yip GK, Shum AHC, Wong KKY, Tsia KK. Microfluidic Imaging Flow Cytometry by Asymmetric-detection Time-stretch Optical Microscopy (ATOM). J Vis Exp 2017. [PMID: 28715367 DOI: 10.3791/55840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Scaling the number of measurable parameters, which allows for multidimensional data analysis and thus higher-confidence statistical results, has been the main trend in the advanced development of flow cytometry. Notably, adding high-resolution imaging capabilities allows for the complex morphological analysis of cellular/sub-cellular structures. This is not possible with standard flow cytometers. However, it is valuable for advancing our knowledge of cellular functions and can benefit life science research, clinical diagnostics, and environmental monitoring. Incorporating imaging capabilities into flow cytometry compromises the assay throughput, primarily due to the limitations on speed and sensitivity in the camera technologies. To overcome this speed or throughput challenge facing imaging flow cytometry while preserving the image quality, asymmetric-detection time-stretch optical microscopy (ATOM) has been demonstrated to enable high-contrast, single-cell imaging with sub-cellular resolution, at an imaging throughput as high as 100,000 cells/s. Based on the imaging concept of conventional time-stretch imaging, which relies on all-optical image encoding and retrieval through the use of ultrafast broadband laser pulses, ATOM further advances imaging performance by enhancing the image contrast of unlabeled/unstained cells. This is achieved by accessing the phase-gradient information of the cells, which is spectrally encoded into single-shot broadband pulses. Hence, ATOM is particularly advantageous in high-throughput measurements of single-cell morphology and texture - information indicative of cell types, states, and even functions. Ultimately, this could become a powerful imaging flow cytometry platform for the biophysical phenotyping of cells, complementing the current state-of-the-art biochemical-marker-based cellular assay. This work describes a protocol to establish the key modules of an ATOM system (from optical frontend to data processing and visualization backend), as well as the workflow of imaging flow cytometry based on ATOM, using human cells and micro-algae as the examples.
Collapse
Affiliation(s)
- Anson H L Tang
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | - Queenie T K Lai
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | - Bob M F Chung
- Department of Mechanical Engineering, The University of Hong Kong
| | - Kelvin C M Lee
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | - Aaron T Y Mok
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | - G K Yip
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | | | - Kenneth K Y Wong
- Department of Electrical and Electronic Engineering, The University of Hong Kong
| | - Kevin K Tsia
- Department of Electrical and Electronic Engineering, The University of Hong Kong;
| |
Collapse
|
15
|
Tan S, Yang L, Wei X, Li C, Chen N, Tsia KK, Wong KKY. High-speed wavelength-swept source at 2.0 μm and its application in imaging through a scattering medium. OPTICS LETTERS 2017; 42:1540-1543. [PMID: 28409792 DOI: 10.1364/ol.42.001540] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report a high-speed wavelength-swept source operating at 2.0 μm through advanced time-stretch technology. It sweeps over 30 nm at a speed of 3.3×109 nm/s and a repetition rate of ∼19 MHz. To the best of our knowledge, this is the first time that a megahertz-stable swept source has been implemented at such a long wavelength. A wide bandwidth is enabled by a simple mode-locked fiber laser that covers a wavelength range of ∼60 nm. The all-optical wavelength sweeping is realized by a chirped fiber Bragg grating (CFBG), which shows a superior temporal stability and power efficiency, compared with commonly used dispersive fibers, particularly in the 2.0 μm wavelength window. To showcase its specialties, here we employ it to perform high-speed spectrally-encoded microscopy (i.e., time-stretch imaging) through a scattering medium at a line-scan rate of up to ∼19 MHz. Better image quality is achieved, compared with a conventional imaging window at 1.0 μm. It is believed that the potential applications of this new high-speed swept source will benefit the transient diagnosis that requires deep penetration through a scattering medium.
Collapse
|
16
|
All-passive pixel super-resolution of time-stretch imaging. Sci Rep 2017; 7:44608. [PMID: 28303936 PMCID: PMC5356014 DOI: 10.1038/srep44608] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 02/09/2017] [Indexed: 12/23/2022] Open
Abstract
Based on image encoding in a serial-temporal format, optical time-stretch imaging entails a stringent requirement of state-of-the-art fast data acquisition unit in order to preserve high image resolution at an ultrahigh frame rate - hampering the widespread utilities of such technology. Here, we propose a pixel super-resolution (pixel-SR) technique tailored for time-stretch imaging that preserves pixel resolution at a relaxed sampling rate. It harnesses the subpixel shifts between image frames inherently introduced by asynchronous digital sampling of the continuous time-stretch imaging process. Precise pixel registration is thus accomplished without any active opto-mechanical subpixel-shift control or other additional hardware. Here, we present the experimental pixel-SR image reconstruction pipeline that restores high-resolution time-stretch images of microparticles and biological cells (phytoplankton) at a relaxed sampling rate (≈2-5 GSa/s)-more than four times lower than the originally required readout rate (20 GSa/s) - is thus effective for high-throughput label-free, morphology-based cellular classification down to single-cell precision. Upon integration with the high-throughput image processing technology, this pixel-SR time-stretch imaging technique represents a cost-effective and practical solution for large scale cell-based phenotypic screening in biomedical diagnosis and machine vision for quality control in manufacturing.
Collapse
|
17
|
Klein T, Huber R. High-speed OCT light sources and systems [Invited]. BIOMEDICAL OPTICS EXPRESS 2017; 8:828-859. [PMID: 28270988 PMCID: PMC5330584 DOI: 10.1364/boe.8.000828] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/02/2017] [Accepted: 01/03/2017] [Indexed: 05/18/2023]
Abstract
Imaging speed is one of the most important parameters that define the performance of optical coherence tomography (OCT) systems. During the last two decades, OCT speed has increased by over three orders of magnitude. New developments in wavelength-swept lasers have repeatedly been crucial for this development. In this review, we discuss the historical evolution and current state of the art of high-speed OCT systems, with focus on wavelength swept light sources and swept source OCT systems.
Collapse
Affiliation(s)
- Thomas Klein
- Optores GmbH, Gollierstr. 70, 80339 Munich, Germany
| | - Robert Huber
- Institut für Biomedizinische Optik, Universität zu Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany
| |
Collapse
|
18
|
Wei X, Kong C, Sy S, Ko H, Tsia KK, Wong KKY. Ultrafast time-stretch imaging at 932 nm through a new highly-dispersive fiber. BIOMEDICAL OPTICS EXPRESS 2016; 7:5208-5217. [PMID: 28018737 PMCID: PMC5175564 DOI: 10.1364/boe.7.005208] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/12/2016] [Accepted: 11/12/2016] [Indexed: 05/25/2023]
Abstract
Optical glass fiber has played a key role in the development of modern optical communication and attracted the biotechnology researcher's great attention because of its properties, such as the wide bandwidth, low attenuation and superior flexibility. For ultrafast optical imaging, particularly, it has been utilized to perform MHz time-stretch imaging with diffraction-limited resolutions, which is also known as serial time-encoded amplified microscopy (STEAM). Unfortunately, time-stretch imaging with dispersive fibers has so far mostly been demonstrated at the optical communication window of 1.5 μm due to lack of efficient dispersive optical fibers operating at the shorter wavelengths, particularly at the bio-favorable window, i.e., <1.0 μm. Through fiber-optic engineering, here we demonstrate a 7.6-MHz dual-color time-stretch optical imaging at bio-favorable wavelengths of 932 nm and 466 nm. The sensitivity at such a high speed is experimentally identified in a slow data-streaming manner. To the best of our knowledge, this is the first time that all-optical time-stretch imaging at ultrahigh speed, high sensitivity and high chirping rate (>1 ns/nm) has been demonstrated at a bio-favorable wavelength window through fiber-optic engineering.
Collapse
Affiliation(s)
- Xiaoming Wei
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Cihang Kong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Samuel Sy
- Department of Electronic Engineering, Faculty of Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Ho Ko
- Department of Medicine and Therapeutics, Prince of Wales Hospital, Faculty of Medicine, Chinese University of Hong Kong, Hong Kong, China
- Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Kevin K. Tsia
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| | - Kenneth K. Y. Wong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong, China
| |
Collapse
|
19
|
Wei X, Kong C, Samanta GK, Tsia KK, Wong KKY. Self-healing highly-chirped fiber laser at 1.0 μm. OPTICS EXPRESS 2016; 24:27577-27586. [PMID: 27906329 DOI: 10.1364/oe.24.027577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We demonstrate a MHz wavelength-swept fiber laser with diffraction-free and self-healing properties at the bio-favorable wavelength window of 1.0 μm. This ultrafast wavelength sweeping at a high chirp rate is all-optically realized through a newly-designed dispersive fiber that can provide a dispersion amount up to -1.7 ns/nm. It is 8 times larger than the standard single-mode fiber at this window and by adopting a double-pass configuration, the dispersion amount can be further increased to about -3.5 ns/nm, which is 23 times larger than what has previously been demonstrated. Its beam profile, a 2D Airy function, shows no obvious diffraction within a propagation distance of 2 meters and furthermore, the self-healing property is also verified by blocking the main lobe of the laser beam. This is the first wavelength-swept fiber laser equipped with diffraction-free and self-healing properties at the bio-favorable window. We believe that such effort can enable real-time data processing and a deeper penetration for the high-speed spectroscopic applications in the turbid environment.
Collapse
|
20
|
Hu S, Yao J, Liu M, Luo AP, Luo ZC, Xu WC. Gain-guided soliton fiber laser with high-quality rectangle spectrum for ultrafast time-stretch microscopy. OPTICS EXPRESS 2016; 24:10786-10796. [PMID: 27409899 DOI: 10.1364/oe.24.010786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The ultrafast time-stretch microscopy has been proposed to enhance the temporal resolution of a microscopy system. The optical source is a key component for ultrafast time-stretch microscopy system. Herein, we reported on the gain-guided soliton fiber laser with high-quality rectangle spectrum for ultrafast time-stretch microscopy. By virtue of the excellent characteristics of the gain-guided soliton, the output power and the 3-dB bandwidth of the stable mode-locked soliton could be up to 3 mW and 33.7 nm with a high-quality rectangle shape, respectively. With the proposed robust optical source, the ultrafast time-stretch microscopy with the 49.6 μm resolution and a scan rate of 11 MHz was achieved without the external optical amplification. The obtained results demonstrated that the gain-guided soliton fiber laser could be used as an alternative high-quality optical source for ultrafast time-stretch microscopy and will introduce some applications in fields such as biology, chemical, and optical sensing.
Collapse
|
21
|
Lau AKS, Shum HC, Wong KKY, Tsia KK. Optofluidic time-stretch imaging - an emerging tool for high-throughput imaging flow cytometry. LAB ON A CHIP 2016; 16:1743-56. [PMID: 27099993 DOI: 10.1039/c5lc01458a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Optical imaging is arguably the most effective tool to visualize living cells with high spatiotemporal resolution and in a nearly noninvasive manner. Driven by this capability, state-of-the-art cellular assay techniques have increasingly been adopting optical imaging for classifying different cell types/stages, and thus dissecting the respective cellular functions. However, it is still a daunting task to image and characterize cell-to-cell variability within an enormous and heterogeneous population - an unmet need in single-cell analysis, which is now widely advocated in modern biology and clinical diagnostics. The challenge stems from the fact that current optical imaging technologies still lack the practical speed and sensitivity for measuring thousands to millions of cells down to the single-cell precision. Adopting the wisdom in high-speed fiber-optics communication, optical time-stretch imaging has emerged as a completely new optical imaging concept which is now proven for ultrahigh-throughput optofluidic single-cell imaging, at least 1-2 orders-of-magnitude higher (up to ∼100 000 cells per second) compared to the existing imaging flow cytometers. It also uniquely enables quantification of intrinsic biophysical markers of individual cells - a largely unexploited class of single-cell signatures that is known to be correlated with the overwhelmingly investigated biochemical markers. With the aim of reaching a wider spectrum of experts specializing in cellular assay developments and applications, this paper highlights the essential basics of optical time-stretch imaging, followed by reviewing the recent developments and applications of optofluidic time-stretch imaging. We will also discuss the current challenges of this technology, in terms of providing new insights in basic biology and enriching the clinical diagnostic toolsets.
Collapse
Affiliation(s)
- Andy K S Lau
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong, China.
| | - Ho Cheung Shum
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong, China
| | - Kenneth K Y Wong
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong, China.
| | - Kevin K Tsia
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Pokfulam Road, Pokfulam, Hong Kong, China.
| |
Collapse
|
22
|
Li B, Wei X, Tan S, Kang J, Wong KKY. Compact and stable temporally magnified tomography using a phase-locked broadband source. OPTICS LETTERS 2016; 41:1562-1565. [PMID: 27192287 DOI: 10.1364/ol.41.001562] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The temporally magnified tomography system is further improved in terms of resolution and imaging stability. We simplify the system configuration and improve the axial resolution simultaneously by utilizing a stabilized all-fiber broadband source. The highly stable spectrum of the source assisted by a phase-locked loop guarantees an improved imaging quality. In addition, the impact of the repetition-rate fluctuation of the source to the system stability is analyzed, which also applies to other temporal imaging systems. Achieving a 90-μm in-air resolution at 89-MHz A-scan rate and improved stability, we are taking one major step toward the practical application of this new optical tomographic modality.
Collapse
|
23
|
Wei X, Lau AKS, Xu Y, Tsia KK, Wong KKY. 28 MHz swept source at 1.0 μm for ultrafast quantitative phase imaging. BIOMEDICAL OPTICS EXPRESS 2015; 6:3855-64. [PMID: 26504636 PMCID: PMC4605045 DOI: 10.1364/boe.6.003855] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Revised: 08/18/2015] [Accepted: 08/31/2015] [Indexed: 05/04/2023]
Abstract
Emerging high-throughput optical imaging modalities, in particular those providing phase information, necessitate a demanding speed regime (e.g. megahertz sweep rate) for those conventional swept sources; while an effective solution is yet to be demonstrated. We demonstrate a stable breathing laser as inertia-free swept source (BLISS) operating at a wavelength sweep rate of 28 MHz, particularly for the ultrafast interferometric imaging modality at 1.0 μm. Leveraging a tunable dispersion compensation element inside the laser cavity, the wavelength sweep range of BLISS can be tuned from ~10 nm to ~63 nm. It exhibits a good intensity stability, which is quantified by the ratio of standard deviation to the mean of the pulse intensity, i.e. 1.6%. Its excellent wavelength repeatability, <0.05% per sweep, enables the single-shot imaging at an ultrafast line-scan rate without averaging. To showcase its potential applications, it is applied to the ultrafast (28-MHz line-scan rate) interferometric time-stretch (iTS) microscope to provide quantitative morphological information on a biological specimen at a lateral resolution of 1.2 μm. This fiber-based inertia-free swept source is demonstrated to be robust and broadband, and can be applied to other established imaging modalities, such as optical coherence tomography (OCT), of which an axial resolution better than 12 μm can be achieved.
Collapse
|
24
|
Wei X, Tan S, Mussot A, Kudlinski A, Tsia KK, Wong KKY. 110 nm versatile fiber optical parametric amplifier at 1.0 μm. OPTICS LETTERS 2015; 40:4090-4093. [PMID: 26368719 DOI: 10.1364/ol.40.004090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The fiber optical parametric amplifier (FOPA) has been well investigated and widely adopted at the telecommunication window, and outstanding progress has been achieved in areas such as high gain, wide bandwidths, and even flexible gain-spectrum shape. In contrast, a FOPA at the bio-favorable window, 1.0 μm, has been largely underexploited, especially for its relatively limited bandwidth. Here, we demonstrate an all-fiber single-pump FOPA at 1.0 μm with versatile performances, including ultrahigh gain (∼52 dB), wide bandwidth (∼110 nm), and good gain-spectrum flatness (∼3 dB). To showcase the practical applications, the FOPA is utilized to amplify the broadband optical image signal from a spectrally encoded microscopy, yielding a sensitivity enhancement of 47 dB. Thus, it is promising that this all-fiber versatile FOPA works well as an add-on module in boosting sensitivity for existing optical systems at a 1.0 μm window.
Collapse
|
25
|
Wei X, Xu Y, Wong KKY. 1000-1400-nm partially mode-locked pulse from a simple all-fiber cavity. OPTICS LETTERS 2015; 40:3005-3008. [PMID: 26125353 DOI: 10.1364/ol.40.003005] [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
We demonstrate a partially mode-locked pulse laser delivering ultra-wideband optical spectrum, i.e., 1000-1400 nm at 30 dB, from a simple all-fiber short cavity with all-normal dispersion. Examined by both real-time temporal and spectral analyzers, the partially mode-locked pulse exhibits double-scale noise-like characteristics-the fast L-shaped mode-locked pulse modulated by slow free-running Q-switched envelopes. Moreover, the statistical analysis as a function of its optical bandwidth shows that the spectral tuning does not compromise the temporal stability, but affects the pulsing periodicity. It is believed that the wide spectrum of knowledge obtained here would enrich the field of noise-like pulse, such as being beneficial to the rogue wave generation.
Collapse
|
26
|
Li B, Zhang C, Kang J, Wei X, Tan S, Wong KKY. 109 MHz optical tomography using temporal magnification. OPTICS LETTERS 2015; 40:2965-2968. [PMID: 26125343 DOI: 10.1364/ol.40.002965] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ultrafast optical tomographic imaging with a 109 MHz A-scan rate is achieved by using temporal magnification. Based on two four-wave mixing (FWM) time lenses with carefully designed group delay dispersion, we construct a temporal imaging system with a magnification factor of 48.3×. The two time-lens scheme not only relaxes the requirement for the pump source but also facilitates the application for tomographic imaging. As a proof-of-concept demonstration, our system achieves an axial resolution of 140 μm in air (∼105 μm in biosample) over a 28 mm depth range with sensitivity up to 55 dB. We then evaluate the imaging performance using a fish-eye lens at a 109 MHz A-scan rate. Utilizing better dispersion-engineered nonlinear media, resolution of less than 5 μm in the biosample with higher sensitivity may be achieved. We believe this scheme will provide a promising solution for video-rate 3D tomographic imaging.
Collapse
|
27
|
Xu J, Wei X, Yu L, Zhang C, Xu J, Wong KKY, Tsia KK. High-performance multi-megahertz optical coherence tomography based on amplified optical time-stretch. BIOMEDICAL OPTICS EXPRESS 2015; 6:1340-50. [PMID: 25909017 PMCID: PMC4399672 DOI: 10.1364/boe.6.001340] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/16/2015] [Accepted: 03/16/2015] [Indexed: 05/18/2023]
Abstract
As the key prerequisite of high-speed volumetric structural and functional tissue imaging in real-time, scaling the A-scan rate beyond MHz has been one of the major pursuits in the development of optical coherence tomography (OCT). Along with a handful of techniques enabling multi-MHz, amplified optical time-stretch OCT (AOT-OCT) has recently been demonstrated as a viable alternative for ultrafast swept-source OCT well above MHz without the need for the mechanical wavelength-tuning mechanism. In this paper, we report a new generation of AOT-OCT demonstrating superior performance to its older generation and all other time-stretch-based OCT modalities in terms of shot-to-shot stability, sensitivity (~90dB), roll-off performance (>4 mm/dB) and A-scan rate (11.5 MHz). Such performance is mainly attributed to the combined contribution from the stable operation of the broadband and compact mode-locked fiber laser as well as the optical amplification in-line with the time-stretch process. The system allows us, for the first time, to deliver volumetric time-stretch-based OCT of biological tissues with the single-shot A-scan rate beyond 10 MHz. Comparing with the existing high-speed OCT systems, the inertia-free AOT-OCT shows promises to realize high-performance 3D OCT imaging at video rate.
Collapse
|
28
|
Huo T, Wang C, Zhang X, Chen T, Liao W, Zhang W, Ai S, Hsieh JC, Xue P. Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:030503. [PMID: 25803185 DOI: 10.1117/1.jbo.20.3.030503] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 03/06/2015] [Indexed: 05/20/2023]
Abstract
We present an ultrahigh-speed optical coherence tomography (OCT) based on an all-optical swept-source with an A-scan rate of 40 MHz. The inertia-free swept-source, which has its output power of 41.2 mW and tuning range of 40 nm and high scan linearity in wavenumber with Pearson's correlation coefficients r of 0.9996, consists of a supercontinuum laser, an optical band-pass filter, a linearly chirped fiber Bragg grating, an erbium-doped fiber amplifier, and two buffer stages. With sensitivity of 87 dB, high-speed OCT imaging of biological tissue in vivo is also demonstrated.
Collapse
|