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Wang W, Wen J, Sheng Y, Wei C, Kong C, Liu Y, Wei X, Yang Z. Shot-Noise Limited Nonlinear Optical Imaging Excited With GHz Femtosecond Pulses and Denoised by Deep-Learning. JOURNAL OF BIOPHOTONICS 2024; 17:e202400186. [PMID: 39218434 DOI: 10.1002/jbio.202400186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 07/11/2024] [Accepted: 07/25/2024] [Indexed: 09/04/2024]
Abstract
Multiphoton fluorescence microscopy excited with femtosecond pulses at high repetition rates, particularly in the range of 100's MHz to GHz, offers an alternative solution to suppress photoinduced damage to biological samples, for example, photobleaching. Here, we demonstrate the use of a U-Net-based deep-learning algorithm for suppressing the inherent shot noise of the two-photon fluorescence images excited with GHz femtosecond pulses. With the trained denoising neural network, the image quality of the representative two-photon fluorescence images of the biological samples is shown to be significantly improved. Moreover, for input raw images with even SNR reduced to -4.76 dB, the trained denoising network can recover the main image structure from noise floor with acceptable fidelity and spatial resolution. It is anticipated that the combination of GHz femtosecond pulses and deep-learning denoising algorithm can be a promising solution for eliminating the trade-off between photoinduced damage and image quality in nonlinear optical imaging platforms.
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Affiliation(s)
- Wenlong Wang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
- State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, China
- Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China University of Technology, Guangzhou, China
| | - Junpeng Wen
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
- State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, China
- Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China University of Technology, Guangzhou, China
| | - Yuke Sheng
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
- State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, China
- Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China University of Technology, Guangzhou, China
| | - Chiyi Wei
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
- State Key Laboratory of Luminescent Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou, China
- Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, South China University of Technology, Guangzhou, China
- Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China University of Technology, Guangzhou, China
| | - Cihang Kong
- Institutes for Translational Brain Research, Fudan University, Shanghai, China
| | - Yalong Liu
- Guangzhou Yangming Laser Technology Co., Ltd, Guangzhou, China
| | - Xiaoming Wei
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
| | - Zhongmin Yang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China Normal University, Guangzhou, Guangdong, China
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2
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He B, Wang W, Wen J, Zhang R, Lin W, Guo Y, Xu Y, Huser T, Wei X, Yang Z. Behavioral dynamics of neuroprotective macrophage polarization in neuropathic pain observed by GHz femtosecond laser two-photon excitation microscopy. JOURNAL OF BIOPHOTONICS 2024; 17:e202400026. [PMID: 38453163 DOI: 10.1002/jbio.202400026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Revised: 02/21/2024] [Accepted: 02/24/2024] [Indexed: 03/09/2024]
Abstract
Macrophage polarization in neurotoxic (M1) or neuroprotective (M2) phenotypes is known to play a significant role in neuropathic pain, but its behavioral dynamics and underlying mechanism remain largely unknown. Two-photon excitation microscopy (2PEM) is a promising functional imaging tool for investigating the mechanism of cellular behavior, as using near-infrared excitation wavelengths is less subjected to light scattering. However, the higher-order photobleaching effect in 2PEM can seriously hamper its applications to long-term live-cell studies. Here, we demonstrate a GHz femtosecond (fs) 2PEM that enables hours-long live-cell imaging of macrophage behavior with reduced higher-order photobleaching effect-by leveraging the repetition rate of fs pulses according to the fluorescence lifetime of fluorophores. Using this new functional 2PEM platform, we measure the polarization characteristics of macrophages, especially the long-term cellular behavior in efferocytosis, unveiling the dynamic mechanism of neuroprotective macrophage polarization in neuropathic pain. These efforts can create new opportunities for understanding long-term cellular dynamic behavior in neuropathic pain, as well as other neurobiological problems, and thus dissecting the underlying complex pathogenesis.
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Affiliation(s)
- Bin He
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Department of Orthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Wenlong Wang
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Junpeng Wen
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Runsen Zhang
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Wei Lin
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Yuankai Guo
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Yue Xu
- Department of Orthodontics, Hospital of Stomatology, Guanghua School of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Thomas Huser
- Biomolecular Photonics, Department of Physics, Bielefeld University, Bielefeld, Germany
| | - Xiaoming Wei
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
| | - Zhongmin Yang
- School of Physics and Optoelectronics; State Key Laboratory of Luminescent Materials and Devices; Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices; Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, South China University of Technology, Guangzhou, China
- Research Institute of Future Technology, South China Normal University, Guangzhou, Guangdong, China
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3
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Okuyucu S, Demirbas U, Thesinga J, Edelmann M, Pergament M, Kärtner F. Diode-pumped passively mode-locked femtosecond Yb:YLF laser at 1.1 GHz. OPTICS EXPRESS 2024; 32:15555-15564. [PMID: 38859203 DOI: 10.1364/oe.518081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Accepted: 03/14/2024] [Indexed: 06/12/2024]
Abstract
We report femtosecond pulse generation at GHz repetition rates with the Yb:YLF gain medium for the first time. A simple, low-cost, and compact architecture is implemented for the potential usage of the system as a low-noise timing jitter source. The system is pumped by 250 mW, 960 nm single-mode diodes from both sides. The semiconductor saturable absorber mirror (SESAM) mode-locked laser is self-starting and generates transform-limited 210 fs long pulses near 1050 nm. The laser's average output power is 40 mW, corresponding to a pulse energy of 36 pJ at 1.1 GHz repetition rate. The measured laser relative intensity noise (RIN) from 1 Hz to 1 MHz is 0.42%. The performance obtained in this initial work is limited by the specifications of the available optics and could be improved significantly by employing custom-designed optical elements.
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4
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Zhang J, Wen J, Wang Y, Wang W, Lin W, Wei X, Yang Z. Watt-level gigahertz femtosecond fiber laser system at 920 nm. OPTICS LETTERS 2022; 47:4941-4944. [PMID: 36181156 DOI: 10.1364/ol.469446] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/01/2022] [Indexed: 06/16/2023]
Abstract
We demonstrate a watt-level femtosecond fiber laser system at 0.9 µm with a repetition rate of >1 GHz, which is the highest value reported so far for a fundamental mode-locked fiber laser. The fiber laser system is seeded by a fundamental mode-locked fiber laser constructed with a home-made highly Nd3+-doped fiber. After external amplification and pulse compression, an output power of 1.75 W and a pulse duration of 309 fs are obtained. This compact fiber laser system is expected to be a promising laser source for biological applications, particularly two-photon excitation microscopy.
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5
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Hamrouni M, Labaye F, Modsching N, Wittwer VJ, Südmeyer T. Efficient high-power sub-50-fs gigahertz repetition rate diode-pumped solid-state laser. OPTICS EXPRESS 2022; 30:30012-30019. [PMID: 36242113 DOI: 10.1364/oe.458866] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 05/30/2022] [Indexed: 06/16/2023]
Abstract
In this article we present a directly diode-pumped high-power Kerr-lens mode-locked Yb:CALGO bulk laser oscillator operating at 1-GHz repetition rate. We report on two laser configurations optimized for either highest average power or shortest pulse duration. In the first configuration optimized for high average power, the oscillator delivers up to 6.9 W of average power, which is the highest average power of any ultrafast laser oscillator operating at gigahertz repetition rate. The 93-fs pulses have a peak power of 64 kW, and the optical-to-optical efficiency amounts to 37%. In the second configuration optimized for short pulse duration, we demonstrate 48-fs pulses at 4.1 W of average power corresponding to a higher peak power of 74 kW with 21% optical-to-optical efficiency. This is the shortest pulse duration and the highest peak power demonstrated by any GHz-class Yb-based laser oscillator. The compact laser setup is directly pumped by a low-cost multimode fiber-coupled laser diode and has a high potential as an economical yet powerful source for various applications.
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6
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Shaw PA, Forsyth E, Haseeb F, Yang S, Bradley M, Klausen M. Two-Photon Absorption: An Open Door to the NIR-II Biological Window? Front Chem 2022; 10:921354. [PMID: 35815206 PMCID: PMC9263132 DOI: 10.3389/fchem.2022.921354] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 05/04/2022] [Indexed: 11/13/2022] Open
Abstract
The way in which photons travel through biological tissues and subsequently become scattered or absorbed is a key limitation for traditional optical medical imaging techniques using visible light. In contrast, near-infrared wavelengths, in particular those above 1000 nm, penetrate deeper in tissues and undergo less scattering and cause less photo-damage, which describes the so-called "second biological transparency window". Unfortunately, current dyes and imaging probes have severely limited absorption profiles at such long wavelengths, and molecular engineering of novel NIR-II dyes can be a tedious and unpredictable process, which limits access to this optical window and impedes further developments. Two-photon (2P) absorption not only provides convenient access to this window by doubling the absorption wavelength of dyes, but also increases the possible resolution. This review aims to provide an update on the available 2P instrumentation and 2P luminescent materials available for optical imaging in the NIR-II window.
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Affiliation(s)
| | | | | | | | | | - Maxime Klausen
- EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh, United Kingdom
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7
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Kageyama T, Hasegawa T. Mode spacing multiplication of optical frequency combs without power loss. OPTICS EXPRESS 2022; 30:19090-19099. [PMID: 36221695 DOI: 10.1364/oe.459554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Accepted: 05/08/2022] [Indexed: 06/16/2023]
Abstract
We demonstrate the mode spacing multiplication of optical frequency combs (OFCs) using interleaving technique. The pulse train of an OFC after interleaving is phase modulated, and phase demodulation is necessary for mode spacing multiplication. This scheme enables mode spacing multiplication without power loss in principle, which is in contrast to the conventional mode filtering technique. During demonstration, the mode spacing of the OFC of a mode-locked Er-doped fiber laser (repetition rate of 97 MHz) is quadrupled by the interleaving process and successive phase demodulation.
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8
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Jun SW, Jang H, Kim J, Kim CS. Multiphoton excitation imaging via an actively mode-locked tunable fiber-cavity SOA laser around 800 nm. BIOMEDICAL OPTICS EXPRESS 2022; 13:525-538. [PMID: 35284185 PMCID: PMC8884227 DOI: 10.1364/boe.447010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 06/14/2023]
Abstract
In this study, an active mode-locked tunable pulsed laser (AML-TPL) is proposed to excite picosecond pulsed light with a rapid wavelength tunability of approximately 800 nm for multiphoton microscopy. The AML-TPL is schematically based on a fiber-cavity semiconductor optical amplifier (SOA) configuration to implement a robust and align-free pulsed light source with a duration of 1.6 ps, a repetition rate of 27.9271 MHz, and average output power of over 600 mW. A custom-built multiphoton imaging system was also built to demonstrate the imaging performance of the proposed AML-TPL by comparing with the commercial Ti:Sapphire femtosecond laser. Two-photon excited fluorescence images were successfully acquired using a human breast cancer cell line (MDA-MB-231) stained with acridine orange.
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Affiliation(s)
- Seung Won Jun
- Ground Technology Research Institute, Agency for Defense Development, Daejeon 34186, Republic of Korea
- These authors contributed equally to this work
| | - Hansol Jang
- Department of Cogno-Mechatronics Engineering,
Pusan National University, 2 Busandaehak-ro
63 beon-gil, Busan, 46241, Republic of
Korea
- These authors contributed equally to this work
| | - Jaeheung Kim
- Department of Cogno-Mechatronics Engineering,
Pusan National University, 2 Busandaehak-ro
63 beon-gil, Busan, 46241, Republic of
Korea
| | - Chang-Seok Kim
- Department of Cogno-Mechatronics Engineering,
Pusan National University, 2 Busandaehak-ro
63 beon-gil, Busan, 46241, Republic of
Korea
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9
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Alloush MA, Brenner C, Calò C, Hofmann MR. Femtosecond pulse generation from external cavity diode laser based on self-mode-locking. OPTICS LETTERS 2021; 46:344-347. [PMID: 33449024 DOI: 10.1364/ol.415336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 12/21/2020] [Indexed: 06/12/2023]
Abstract
In this Letter, we report optical pulse generation from a single-section diode gain chip, employed in an external cavity geometry based on the self-mode-locking regime. The gain chip emits light at 1550 nm wavelength range. The external cavity is operated at various repetition rates, ranging from 1 to 2.5 GHz. An optical pulse width of approximately 650 fs is obtained by fitting a Lorentzian distribution. A low RF spectral width of 78.875 kHz is measured corresponding to a low pulse-to-pulse RMS timing jitter of 1.273 ps. This system paves the way towards ultra-compact, cost-effective, and chirp-compensated femtosecond laser pulse sources with adjustable repetition rates.
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10
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Mohr MA, Bushey D, Aggarwal A, Marvin JS, Kim JJ, Marquez EJ, Liang Y, Patel R, Macklin JJ, Lee CY, Tsang A, Tsegaye G, Ahrens AM, Chen JL, Kim DS, Wong AM, Looger LL, Schreiter ER, Podgorski K. jYCaMP: an optimized calcium indicator for two-photon imaging at fiber laser wavelengths. Nat Methods 2020; 17:694-697. [PMID: 32451475 PMCID: PMC7335340 DOI: 10.1038/s41592-020-0835-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 04/14/2020] [Indexed: 11/09/2022]
Abstract
Femtosecond lasers at fixed wavelengths above 1,000 nm are powerful, stable and inexpensive, making them promising sources for two-photon microscopy. Biosensors optimized for these wavelengths are needed for both next-generation microscopes and affordable turn-key systems. Here we report jYCaMP1, a yellow variant of the calcium indicator jGCaMP7 that outperforms its parent in mice and flies at excitation wavelengths above 1,000 nm and enables improved two-color calcium imaging with red fluorescent protein-based indicators.
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Affiliation(s)
- Manuel Alexander Mohr
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule Zurich, Basel, Switzerland
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Daniel Bushey
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Abhi Aggarwal
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jonathan S Marvin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Jeong Jun Kim
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Emiliano Jimenez Marquez
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Universidad Nacional Autonoma de Mexico, Mexico, Mexico
| | - Yajie Liang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Ronak Patel
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - John J Macklin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Chi-Yu Lee
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Arthur Tsang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Getahun Tsegaye
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | | | - Jerry L Chen
- Department of Biology, Boston University, Boston, MA, USA
| | - Douglas S Kim
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Allan M Wong
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Loren L Looger
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Eric R Schreiter
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- GENIE Project, Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Kaspar Podgorski
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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11
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An aspherical microlens assembly for deep brain fluorescence microendoscopy. Biochem Biophys Res Commun 2020; 527:447-452. [PMID: 32336546 DOI: 10.1016/j.bbrc.2020.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 01/08/2023]
Abstract
Fluorescence microendoscopy is becoming a standard technique in neuroscience for visualizing neuronal activity in the deep brain. Gradient refractive index (GRIN) lenses are increasingly used for fluorescence microendoscopy; however, they inherently suffer from strong aberrations and distortion. Aspherical lenses change their radius of curvature with distance from the optical axis and can effectively eliminate spherical aberrations. The use of these lenses has not been fully explored in deep brain fluorescence microendoscopy due to technical difficulties in manufacturing miniature aspherical lenses. In this study, we fabricated a novel microendoscope lens assembly comprised two nested pairs of aspherical microlenses made by precision glass molding. This assembly, which was 0.6 mm in diameter and 7.06 mm in length, was assembled in a stainless steel tube of 0.7 mm outer diameter. This assembly exhibited marked improvements in monochromatic and chromatic aberrations compared with a conventional GRIN lens, and is useful for deep brain fluorescence microendoscopy, as demonstrated by two-photon microendoscopic calcium imaging of R-CaMP1.07-labeled mouse hippocampal CA1 neurons. Our aspherical-lens-based approach offers a non-GRIN-lens alternative for fabrication of microendoscopic lenses.
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12
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Wang F, Pistore V, Riesch M, Nong H, Vigneron PB, Colombelli R, Parillaud O, Mangeney J, Tignon J, Jirauschek C, Dhillon SS. Ultrafast response of harmonic modelocked THz lasers. LIGHT, SCIENCE & APPLICATIONS 2020; 9:51. [PMID: 32257182 PMCID: PMC7113272 DOI: 10.1038/s41377-020-0288-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 03/04/2020] [Accepted: 03/12/2020] [Indexed: 05/20/2023]
Abstract
The use of fundamental modelocking to generate short terahertz (THz) pulses and THz frequency combs from semiconductor lasers has become a routine affair, using quantum cascade lasers (QCLs) as a gain medium. However, unlike classic laser diodes, no demonstrations of harmonic modelocking, active or passive, have been shown in THz QCLs, where multiple pulses per round trip are generated when the laser is modulated at the harmonics of the cavity's fundamental round-trip frequency. Here, using time-resolved THz techniques, we show for the first time harmonic injection and mode-locking in which THz QCLs are modulated at the harmonics of the round-trip frequency. We demonstrate the generation of the harmonic electrical beatnote within a QCL, its injection locking to an active modulation and its direct translation to harmonic pulse generation using the unique ultrafast nature of our approach. Finally, we show indications of self-starting harmonic emission, i.e., without external modulation, where the QCL operates exclusively on a harmonic (up to its 15th harmonic) of the round-trip frequency. This behaviour is supported by time-resolved simulations of induced gain and loss in the system and shows the importance of the electronic, as well as photonic, nature of QCLs. These results open up the prospect of passive harmonic modelocking and THz pulse generation, as well as the generation of low-noise microwave generation in the hundreds of GHz region.
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Affiliation(s)
- Feihu Wang
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Valentino Pistore
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Michael Riesch
- Department of Electrical and Computer Engineering, Technical University of Munich, Arcisstr. 21, 80333 Munich, Germany
| | - Hanond Nong
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Pierre-Baptiste Vigneron
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N-Orsay, 91405 Orsay, Cedex France
| | - Raffaele Colombelli
- Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N-Orsay, 91405 Orsay, Cedex France
| | | | - Juliette Mangeney
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Jerome Tignon
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
| | - Christian Jirauschek
- Department of Electrical and Computer Engineering, Technical University of Munich, Arcisstr. 21, 80333 Munich, Germany
| | - Sukhdeep S. Dhillon
- Laboratoire de Physique de l’Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université de Paris, Paris, France
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13
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Alfieri CGE, Waldburger D, Nürnberg J, Golling M, Keller U. Sub-150-fs pulses from an optically pumped broadband modelocked integrated external-cavity surface emitting laser. OPTICS LETTERS 2019; 44:25-28. [PMID: 30645536 DOI: 10.1364/ol.44.000025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 11/19/2018] [Indexed: 06/09/2023]
Abstract
With a modelocked integrated external-cavity surface emitting laser (MIXSEL) we achieved a pulse duration of 144 fs. The MIXSEL belongs to the family of optically pumped semiconductor disk lasers. The MIXSEL operates at a center wavelength of 1033 nm with a 13-nm full width at half maximum optical bandwidth, at a pulse repetition rate of 2.73 GHz, and at an average output power of 30 mW. This new record result was obtained with an optimized multipair dielectric top-coating, a large bandgap AlAsxP1-x material for strain compensation, a nonperiodic InGaAs quantum well gain structure, and an improved thermal management.
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14
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Highly tunable repetition-rate multiplication of mode-locked lasers using all-fibre harmonic injection locking. Sci Rep 2018; 8:13875. [PMID: 30224734 PMCID: PMC6141577 DOI: 10.1038/s41598-018-31929-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 08/29/2018] [Indexed: 11/18/2022] Open
Abstract
Higher repetition-rate optical pulse trains have been desired for various applications such as high-bit-rate optical communication, photonic analogue-to-digital conversion, and multi-photon imaging. Generation of multi GHz and higher repetition-rate optical pulse trains directly from mode-locked oscillators is often challenging. As an alternative, harmonic injection locking can be applied for extra-cavity repetition-rate multiplication (RRM). Here we have investigated the operation conditions and achievable performances of all-fibre, highly tunable harmonic injection locking-based pulse RRM. We show that, with slight tuning of slave laser length, highly tunable RRM is possible from a multiplication factor of 2 to >100. The resulting maximum SMSR is 41 dB when multiplied by a factor of two. We further characterize the noise properties of the multiplied signal in terms of phase noise and relative intensity noise. The resulting absolute rms timing jitter of the multiplied signal is in the range of 20 fs to 60 fs (10 kHz–1MHz) for different multiplication factors. With its high tunability, simple and robust all-fibre implementation, and low excess noise, the demonstrated RRM system may find diverse applications in microwave photonics, optical communications, photonic analogue-to-digital conversion, and clock distribution networks.
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Waldburger D, Alfieri CGE, Link SM, Meinecke S, Jaurigue LC, Lüdge K, Keller U. Multipulse instabilities of a femtosecond SESAM-modelocked VECSEL. OPTICS EXPRESS 2018; 26:21872-21886. [PMID: 30130890 DOI: 10.1364/oe.26.021872] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/03/2018] [Indexed: 06/08/2023]
Abstract
Optically pumped passively modelocked vertical external-cavity surface-emitting lasers (VECSELs) can generate pulses as short as 100 fs with an intracavity semiconductor saturable absorber mirror (SESAM). Very stable soliton modelocking can be obtained, however, the high-Q-cavity, the short gain lifetime, and the kinetic-hole burning can also support rather complex multipulse instabilities which we analyze in more details here. This onset of multipulse operation limits the maximum average output power with fundamental modelocking and occurs at the roll-over of the cavity round trip reflectivity. Unfortunately, such multipulse operation sometimes can mimic stable modelocking when only limited diagnostics are available.
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Härkönen A, Suomalainen S, Rantamäki A, Nikkinen J, Wang Y, Griebner U, Steinmeyer G, Guina M. 1.34 μm VECSEL mode-locked with a GaSb-based SESAM. OPTICS LETTERS 2018; 43:3353-3356. [PMID: 30004504 DOI: 10.1364/ol.43.003353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 05/26/2018] [Indexed: 06/08/2023]
Abstract
Mode locking of a 1.34 μm vertical external cavity surface emitting laser is demonstrated using a GaSb-based semiconductor saturable absorber mirror (SESAM). The SESAM includes six AlGaSb quantum wells (QWs) with an absorption edge at ∼1.37 μm. The proposed approach has two key benefits: the QWs can be grown lattice matched, and only a small number of Bragg reflector layers is required to provide high reflectivity. Pump-probe measurements also reveal that the AlGaSb/GaSb structure exhibits an intrinsically fast absorption recovery on a picosecond timescale. The mode-locked laser pulse train had a fundamental repetition rate of 1.03 GHz, a pulse duration of ∼5 ps, and a peak power of ∼1.67 W. The demonstration paves the way for exploiting GaSb-based SESAMs for mode locking in the 1.3-2 μm wavelength range, which is not sufficiently addressed by GaAs and InP material systems.
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Malica T, Lin J, Ackemann T, Little DJ, Toomey JP, Pabœuf D, Lubeigt W, Hempler N, Malcolm G, Maker GT, Kane DM. Mapping the dynamical regimes of a SESAM mode-locked VECSEL with a long cavity using time series analysis. OPTICS EXPRESS 2018; 26:16624-16638. [PMID: 30119489 DOI: 10.1364/oe.26.016624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
The different dynamical regions of an optically-pumped SESAM mode-locked, long-cavity VECSEL system with a fundamental pulse repetition frequency of ~200 MHz are investigated. The output power, captured as 250 μs long time series using a sampling rate of 200 GSa/s, for each operating condition of the system, is analyzed to determine the dynamical state. A wavelength range of 985-995 nm and optical pump powers of 10 W-16.3 W is studied. The system produces high quality fundamental passive mode-locking (FML) over an extensive part of the parameter space, but the different dynamical regions outside of FML are the primary focus of this study. We report five types of output: CW emission, FML, mode-locking of a few modes, double pulsing, and, semi-stable 4th harmonic mode-locking. The high sampling rate of the oscilloscope, combined with the long duration of the time series analyzed, enables insight into how the structure and substructure of pulses vary systematically over thousands of round trips of the laser cavity. Higher average output power is obtained in regions characterized by semi-stable 4th harmonic mode-locking than observed for FML, raising whether such average powers might be achieved for FML. The observed dynamic transitions from fundamental mode-locking provide insights into instability challenges in developing a stable, widely tunable, low repetition rate, turn-key system; and to inform future modelling of the system.
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Charan K, Li B, Wang M, Lin CP, Xu C. Fiber-based tunable repetition rate source for deep tissue two-photon fluorescence microscopy. BIOMEDICAL OPTICS EXPRESS 2018; 9:2304-2311. [PMID: 29760989 PMCID: PMC5946790 DOI: 10.1364/boe.9.002304] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/16/2018] [Accepted: 04/17/2018] [Indexed: 05/02/2023]
Abstract
Deep tissue multiphoton imaging requires high peak power to enhance signal and low average power to prevent thermal damage. Both goals can be advantageously achieved through laser repetition rate tuning instead of simply adjusting the average power. We show that the ideal repetition rate for deep two-photon imaging in the mouse brain is between 1 and 10 MHz, and we present a fiber-based source with an arbitrarily tunable repetition rate within this range. The performance of the new source is compared to a mode-locked Ti:Sapphire (Ti:S) laser for in vivo imaging of mouse brain vasculature. At 2.5 MHz, the fiber source requires 5.1 times less average power to obtain the same signal as a standard Ti:S laser operating at 80 MHz.
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Affiliation(s)
- Kriti Charan
- School of Applied Physics and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Bo Li
- School of Applied Physics and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Mengran Wang
- School of Applied Physics and Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Charles P. Lin
- Wellman Center for Photomedicine and Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Chris Xu
- School of Applied Physics and Engineering, Cornell University, Ithaca, NY 14850, USA
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Garcia AM, Magalhes FL, Soares JS, Junior EP, Lima MFRD, Mamede M, Paula AMD. Second harmonic generation imaging of the collagen architecture in prostate cancer tissue. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aaa379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Link SM, Waldburger D, Alfieri CGE, Golling M, Keller U. Coherent beam combining and noise analysis of a colliding pulse modelocked VECSEL. OPTICS EXPRESS 2017; 25:19281-19290. [PMID: 29041121 DOI: 10.1364/oe.25.019281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 07/22/2017] [Indexed: 06/07/2023]
Abstract
Optically-pumped SESAM-modelocked semiconductor disk lasers have become interesting ultrafast lasers with gigahertz pulse repetition rates, high average power and adjustable lasing wavelength. It is well established that colliding pulse modelocking (CPM) can generate both shorter pulses and improved stability. These improvements however typically come at the expense of a more complex ring cavity and two output beams. So far similar modelocking results have been obtained with CPM vertical external-cavity surface-emitting lasers (VECSELs) and with SESAM-modelocked VECSELs or modelocked integrated external-cavity surface-emitting lasers (MIXSELs) in a linear cavity. However coherent beam combining of the two output beams of a CPM VECSEL could result in a significantly higher peak power. This is interesting for example for applications in biomedical microscopy and frequency metrology. Here we demonstrate with a more detailed noise analysis that for both output beams of a CPM VECSEL the pulse repetition rates and the carrier envelope offset frequencies are locked to each other. In contrast to standard SESAM-modelocked VECSELs in a linear cavity, we only have been able to actively stabilize the pulse repetition rate of the CPM VECSEL by cavity length control and not by pump-power control. Furthermore, a first coherent beam combining experiment of the two output beams is demonstrated.
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