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Zhao H, Dai S, Ouyang K, Zhu S, Yin H, Li Z, Chen Z. High-power and narrow-linewidth nanosecond pulsed intracavity crystalline Raman laser operating at 1.7 µm. OPTICS EXPRESS 2024; 32:20852-20861. [PMID: 38859455 DOI: 10.1364/oe.527203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2024] [Accepted: 05/14/2024] [Indexed: 06/12/2024]
Abstract
We report on a high-power and narrow-linewidth nanosecond pulsed intracavity crystalline Raman laser at 1.7 µm. Driven by an acousto-optically Q-switched 1314 nm two-crystal Nd:YLF laser, the highly efficient cascaded YVO4 Raman laser at 1715nm was obtained within the well-designed L-shaped resonator. Thanks to the absence of spatial hole burning in the stimulated Raman scattering process, significant spectral purification of second-Stokes radiation was observed by incorporating a fused silica etalon in the high-Q fundamental cavity. Under the repetition rate of 4 kHz, the highest average output power for single longitudinal mode operation was up to 2.2 W with the aid of precision vibration isolation and precision temperature controlling, corresponding to the pulse duration of ∼2.8 ns and the spectral linewidth of ∼330 MHz. Further increasing the launched pump power, the second-Stokes laser tended toward be always multimode, and the maximum average output power amounted to 4.8 W with the peak power of ∼0.8 MW and the spectral linewidth of ∼0.08 nm. The second-Stokes emission was near diffraction limited with M2 < 1.4 across the whole pump power range.
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Li H, Pei W, Li X, Lei L, Shi J, Zhou Z, Wang Z. Cascaded All-Fiber Gas Raman Laser Oscillator in Deuterium-Filled Hollow-Core Photonic Crystal Fibers. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:661. [PMID: 38668155 PMCID: PMC11055054 DOI: 10.3390/nano14080661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 04/09/2024] [Accepted: 04/10/2024] [Indexed: 04/29/2024]
Abstract
Hollow-core photonic crystal fibers (HC-PCFs) provide an ideal transmission medium and experimental platform for laser-matter interaction. Here, we report a cascaded all-fiber gas Raman laser based on deuterium (D2)-filled HC-PCFs. D2 is sealed into a gas cavity formed by a 49 m-long HC-PCF and solid-core fibers, and two homemade fiber Bragg gratings (FBGs) with the Raman and pump wavelength, respectively, are further introduced. When pumped by a pulsed fiber amplifier at 1540 nm, the pure rotational stimulated Raman scattering of D2 occurs inside the cavity. The first-order Raman laser at 1645 nm can be obtained, realizing a maximum power of ~0.8 W. An all-fiber cascaded gas Raman laser oscillator is achieved by adding another 1645 nm high-reflectivity FBG at the output end of the cavity, reducing the peak power of the cascaded Raman threshold by 11.4%. The maximum cascaded Raman power of ~0.5 W is obtained when the pump source is at its maximum, and the corresponding conversion efficiency inside the cavity is 21.4%, which is 1.8 times that of the previous configuration. Moreover, the characteristics of the second-order Raman lasers at 1695 nm and 1730 nm are also studied thoroughly. This work provides a significant method for realizing all-fiber cascaded gas Raman lasers, which is beneficial for expanding the output wavelength of fiber gas lasers with a good stability and compactivity.
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Affiliation(s)
- Hao Li
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Wenxi Pei
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Xuanxi Li
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Luohao Lei
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Jing Shi
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
| | - Zhiyue Zhou
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
- State Key Laboratory of Pulsed Power Laser Technology, Changsha 410073, China
| | - Zefeng Wang
- College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha 410073, China; (H.L.); (W.P.); (X.L.); (L.L.); (J.S.); (Z.Z.)
- Nanhu Laser Laboratory, National University of Defense Technology, Changsha 410073, China
- State Key Laboratory of Pulsed Power Laser Technology, Changsha 410073, China
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Zhong J, Zhang Y, Chen X, Tong S, Deng X, Huang J, Li Z, Zhang C, Gao Z, Li J, Qiu P, Wang K. In vivo deep brain multiphoton fluorescence imaging emitting at NIR-I and NIR-II and excited at NIR-IV. JOURNAL OF BIOPHOTONICS 2024; 17:e202300422. [PMID: 38211977 DOI: 10.1002/jbio.202300422] [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: 10/10/2023] [Revised: 11/28/2023] [Accepted: 12/03/2023] [Indexed: 01/13/2024]
Abstract
Multiphoton microscopy (MPM) enables deep brain imaging. Three optical windows: NIR-I, NIR-II, and NIR-III are widely used. Recently, NIR-IV (the 2200 nm window) has been demonstrated to be the last and longest window for deep tissue MPM. However, so far MPM covers only two optical windows labeled by single fluorescent probe, one for emission and one for excitation. Here we demonstrate in vivo deep brain MPM covering three optical windows, with emission at NIR-I, NIR-II, and excitation at NIR-IV, labeled by ICG. The innovations include: (1) characterizing both 3-photon excitation and emission properties of ICG emitting at both NIR-I and NIR-II, in water, plasma, and circulating blood; (2) a home-built multiphoton microscope with simultaneous dual channel detection, with which we demonstrate deep brain MPM 950 μm (NIR-I) and 850 μm (NIR-II) into the mouse brain in vivo, verifying that multi-optical window MPM is promising for deep brain imaging.
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Affiliation(s)
- Jincheng Zhong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Yingxian Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Xinlin Chen
- Advanced Life Imaging Lab, Wenzhou Institute, University of Chinese Academy of Sciences, Zhejiang, China
| | - Shen Tong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Xiangquan Deng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Jie Huang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Zhenhui Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Chi Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Zhiang Gao
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Jia Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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Zhang Y, Zhong J, Cheng H, Huang J, Li Z, Zhang C, Gao Z, Xu Z, Xu G, Qiu P, Wang K. Comparison of the penetration depth in mouse brain in vivo through 3PF imaging using AIE nanoparticle labeling and THG imaging within the 1700 nm window. NANOSCALE ADVANCES 2024; 6:511-515. [PMID: 38235073 PMCID: PMC10790977 DOI: 10.1039/d3na00871a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 12/05/2023] [Indexed: 01/19/2024]
Abstract
3-Photon microscopy (3PM) excited at the 1700 nm window features a smaller tissue attenuation and hence a larger penetration depth in brain imaging compared with other excitation wavelengths in vivo. While the comparison of the penetration depth quantified by effective attenuation length le with other excitation wavelengths have been extensively investigated, comparison within the 1700 nm window has never been demonstrated. This is mainly due to the lack of a proper excitation laser source and characterization of the in vivo emission properties of fluorescent labels within this window. Herein, we demonstrate detailed measurements and comparison of le through the 3-photon imaging of the mouse brain in vivo, at different excitation wavelengths (1600 nm, 1700 nm, and 1800 nm). 3PF imaging and in vivo spectrum measurements were performed using AIE nanoparticle labeling. Our results show that le derived from both 3PF imaging and THG imaging is the largest at 1700 nm, indicating that it enables the deepest penetration in brain imaging in vivo.
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Affiliation(s)
- Yingxian Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Jincheng Zhong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Hui Cheng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Jie Huang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Zhenhui Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Chi Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Zhiang Gao
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Zhourui Xu
- School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University Shenzhen Guangdong 518055 China
| | - Gaixia Xu
- School of Biomedical Engineering, Shenzhen University Medical School, Shenzhen University Shenzhen Guangdong 518055 China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
| | - Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University Shenzhen 518060 China
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Krylov A, Senatorov A, Gladyshev A, Yatsenko Y, Kosolapov A, Kolyadin A, Khudyakov M, Likhachev M, Bufetov I. 10-µJ-level femtosecond pulse generation in the erbium CPA fiber source with microstructured hollow-core fiber assisted delivery and nonlinear frequency conversion. APPLIED OPTICS 2023; 62:5745-5754. [PMID: 37707192 DOI: 10.1364/ao.494799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 06/24/2023] [Indexed: 09/15/2023]
Abstract
We report on the development of a chirped pulse amplification (CPA) designed erbium fiber source with a hybrid high-power amplifier, which is composed of erbium-doped and erbium/ytterbium-co-doped double-clad large-mode-area fibers. Stretched pulses from the high-power amplifier with up to 21.9 µJ energy and 198.5 kHz repetition rate are dechirped in the transmission grating pair-based compressor with 73% efficiency, yielding as short as 742 fs duration with 15.8 µJ energy and ≈13M W peak power (maximum average power up to 3.14 W) at the central wavelength of 1.56 µm. Compressed pulses are coupled into microstructured negative-curvature hollow-core fibers with a single row capillary cladding and different core sizes of 34 µm and 75 µm in order to realize femtosecond pulse delivery with a diffraction-limited output beam (M 2≤1.09) and demonstrate ∼200n J Stokes pulse generation at 1712 nm via rotational SRS in pressurized hydrogen (H 2). We believe that the developed system may be a prospect for high-precision material processing and other high-energy and high-peak-power laser applications.
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Sun M, Cui J, Yu B, Feng Z, Li Y, Chen Y, Wang Y, Feng L, Liu Y, Wang A. High-power, sub-100-fs, 1600-1700-nm all-fiber laser for deep multiphoton microscopy. OPTICS EXPRESS 2023; 31:24298-24306. [PMID: 37475260 DOI: 10.1364/oe.493694] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 06/09/2023] [Indexed: 07/22/2023]
Abstract
The 1600-1700-nm ultrafast fiber lasers attract great interests in the deep multiphoton microscopy, due to the reduced levels of the tissue scattering and absorption. Here, we report on the 86.7-MHz, 717-mW, 91.2-fs, all-fiber laser located in the spectral range from 1600 nm to 1700nm. The soliton self-frequency shift (SSFS) was introduced into the Er:Yb co-doped fiber amplifier (EYDFA) to generate the high-power, 1600-1700-nm Raman soliton. Detailed investigations of the nonlinear fiber amplification process were implemented in optimizing the generated Raman soliton pulses. The miniature multiphoton microscopy was further realized with this home-built laser source. The clearly imaging results can be achieved by collecting the generated harmonic signals from the mouse tail skin tissue with a penetration depth of ∼500 µm. The experimental results indicate the great potential in utilizing this 1600-1700-nm fiber laser in the deep multiphoton microscopy.
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Deng X, Ma X, Zhang W, Qin M, Xie W, Qiu P, Yin J, Wang K. In vivo deep-brain 2-photon fluorescent microscopy labeled with near-infrared dyes excited at the 1700 nm window. Anal Chim Acta 2023; 1255:341118. [PMID: 37032053 DOI: 10.1016/j.aca.2023.341118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/01/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023]
Abstract
2-Photon fluorescence microscopy (2PFM) is an indispensable imaging technology for neuroscience. However, the imaging depth is usually limited to the cortical layer in mouse brain in vivo. Here, we demonstrate deep brain 2PFM in vivo excited at the 1700 nm window, using IR780 and aza-IR780 as fluorescent labels. Our detailed characterization of the multiphoton excitation and emission properties of IR780 and aza-IR780 show that: (1) IR780 or aza-IR780 generate 2-photon fluorescence excited at the 1700 nm window and are promising for 2PFM; (2) aza-IR780 exhibits a larger ησ2 with better anti-photobleaching property compared to IR780; The 2-photon action cross-sections of IR780 and aza-IR780 in plasma are an order-of-magnitude larger than those in PBS; (3) In vivo 2-photon emission spectra for both dyes show a notable red shift compared to those in vitro. Based on these characterization results, we demonstrate deep brain 2PFM labeled by them. A maximum imaging depth of 1585 μm (labeled by IR780) and 1800 μm (labeled by aza-IR780) into the mouse brain in vivo readily penetrates the subcortical region of hippocampus. Besides, a maximum of 1528 μm hemodynamic imaging depth is realized via 2PFM with aza-IR780 labeling, enabling us to measure blood flow speed in the hippocampus.
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Affiliation(s)
- Xiangquan Deng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Xiaoxie Ma
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Hubei International Scientific and Technological Cooperation Base of Pesticide and Green Synthesis, International Joint Research Center for Intelligent Biosensing Technology and Health, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Wanjian Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Mengyuan Qin
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Weixin Xie
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Jun Yin
- Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Hubei International Scientific and Technological Cooperation Base of Pesticide and Green Synthesis, International Joint Research Center for Intelligent Biosensing Technology and Health, College of Chemistry, Central China Normal University, Wuhan, 430079, China.
| | - Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060, China.
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Tong S, Zhong J, Chen X, Deng X, Huang J, Zhang Y, Qin M, Li Z, Cheng H, Zhang W, Zheng L, Xie W, Qiu P, Wang K. In Vivo Deep-Brain 3- and 4-Photon Fluorescence Imaging of Subcortical Structures Labeled by Quantum Dots Excited at the 2200 nm Window. ACS NANO 2023; 17:3686-3695. [PMID: 36799427 DOI: 10.1021/acsnano.2c10724] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Multiphoton microscopy (MPM) is an enabling technology for visualizing deep-brain structures at high spatial resolution in vivo. Within the low tissue absorption window, shifting to longer excitation wavelengths reduces tissue scattering and boosts penetration depth. Recently, the 2200 nm excitation window has emerged as the last and longest window suitable for deep-brain MPM. However, multiphoton fluorescence imaging at this window has not been demonstrated, due to the lack of characterization of multiphoton properties of fluorescent labels. Here we demonstrate technologies for measuring both the multiphoton excitation and emission properties of fluorescent labels at the 2200 nm window, using (1) 3-photon (ησ3) and 4-photon action cross sections (ησ4) and (2) 3-photon and 4-photon emission spectra both ex vivo and in vivo of quantum dots. Our results show that quantum dots have exceptionally large ησ3 and ησ4 for efficient generation of multiphoton fluorescence. Besides, the 3-photon and 4-photon emission spectra of quantum dots are essentially identical to those of one-photon emission, which change negligibly subject to the local environment of circulating blood. Based on these characterization results, we further demonstrate deep-brain vasculature imaging in vivo. Due to the superb multiphoton properties of quantum dots, 3-photon and 4-photon fluorescence imaging reaches a maximum brain imaging depth of 1060 and 940 μm below the surface of a mouse brain, respectively, which enables the imaging of subcortical structures. We thus fill the last gap in multiphoton fluorescence imaging in terms of wavelength selection.
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Affiliation(s)
- Shen Tong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Jincheng Zhong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Xinlin Chen
- Advanced Life Imaging Lab, Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325001, China
| | - Xiangquan Deng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Jie Huang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Yingxian Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Mengyuan Qin
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Zhenhui Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Hui Cheng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Wanjian Zhang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Lei Zheng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Weixin Xie
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
| | - Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, China
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9
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Guo Y, Han H, Wang L, Zhu Y, Yang Z, Weng X, Yan W, Qu J. Ultra-long anti-diffracting beam volume imaging using a single-photon excitation microscope. OPTICS EXPRESS 2022; 30:30271-30278. [PMID: 36242134 DOI: 10.1364/oe.467411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/15/2022] [Indexed: 06/16/2023]
Abstract
We studied a novel volumetric single-photon excitation microscope with an ultralong anti-diffracting (UAD) beam as illumination. Volumetric fluorescence image direct mapping showed that the axial imaging range of the UAD beam was approximately 14 times and 2 times that of conventional Gaussian and Airy beams, respectively, while maintaining a narrow lateral width. We compared the imaging capabilities of the Gaussian, Airy, and UAD modes through a strongly scattering environment mixed with fluorescent microspheres and agarose gel. Thick samples were scanned layer by layer in the Gaussian, Airy, and UAD modes, and then the three-dimensional structural information was projected onto a two-dimensional image. Benefiting from the longer focal length of the UAD beam, a deeper axial projection was provided, and the volume imaging speed was vastly increased. To demonstrate the performances of the UAD microscope, we performed dynamic volumetric imaging on the cardiovascular system of zebrafish labeled with green fluorescent proteins in the three modes and dynamically monitored substance transport in zebrafish blood vessels. In addition, the symmetrical curve trajectory of the UAD beam and the axial depth of the lateral position can be used for localization of micro-objects.
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Sinefeld D, Xia F, Wang M, Wang T, Wu C, Yang X, Paudel HP, Ouzounov DG, Bifano TG, Xu C. Three-Photon Adaptive Optics for Mouse Brain Imaging. Front Neurosci 2022; 16:880859. [PMID: 35692424 PMCID: PMC9185169 DOI: 10.3389/fnins.2022.880859] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 05/05/2022] [Indexed: 11/24/2022] Open
Abstract
Three-photon microscopy (3PM) was shown to allow deeper imaging than two-photon microscopy (2PM) in scattering biological tissues, such as the mouse brain, since the longer excitation wavelength reduces tissue scattering and the higher-order non-linear excitation suppresses out-of-focus background fluorescence. Imaging depth and resolution can further be improved by aberration correction using adaptive optics (AO) techniques where a spatial light modulator (SLM) is used to correct wavefront aberrations. Here, we present and analyze a 3PM AO system for in vivo mouse brain imaging. We use a femtosecond source at 1300 nm to generate three-photon (3P) fluorescence in yellow fluorescent protein (YFP) labeled mouse brain and a microelectromechanical (MEMS) SLM to apply different Zernike phase patterns. The 3P fluorescence signal is used as feedback to calculate the amount of phase correction without direct phase measurement. We show signal improvement in the cortex and the hippocampus at greater than 1 mm depth and demonstrate close to diffraction-limited imaging in the cortical layers of the brain, including imaging of dendritic spines. In addition, we characterize the effective volume for AO correction within brain tissues, and discuss the limitations of AO correction in 3PM of mouse brain.
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Affiliation(s)
- David Sinefeld
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
- Department of Applied Physics, Electro-Optics Engineering Faculty, Jerusalem College of Technology, Jerusalem, Israel
- *Correspondence: David Sinefeld,
| | - Fei Xia
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
- Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY, United States
| | - Mengran Wang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | - Tianyu Wang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | - Chunyan Wu
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | - Xusan Yang
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | - Hari P. Paudel
- Photonics Center, Boston University, Boston, MA, United States
| | - Dimitre G. Ouzounov
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
| | | | - Chris Xu
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, United States
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Wang K, Pan Y, Tong S, Chen X, Lu Y, Qiu P. Deep-skin multiphoton microscopy in vivo excited at 1600 nm: A comparative investigation with silicone oil and deuterium dioxide immersion. JOURNAL OF BIOPHOTONICS 2021; 14:e202100076. [PMID: 34160142 DOI: 10.1002/jbio.202100076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/17/2021] [Accepted: 06/10/2021] [Indexed: 06/13/2023]
Abstract
Multiphoton microscopy (MPM) excited at the 1700-nm window has enabled deep-tissue penetration in biological tissue, especially brain. MPM of skin may also benefit from this deep-penetration capability. Skin is a layered structure with varying refractive index (from 1.34 to 1.5). Consequently, proper immersion medium should be selected when imaging with high numerical aperture objective lens. To provide guidelines for immersion medium selection for skin MPM, here we demonstrate comparative experimental investigation of deep-skin MPM excited at 1600 nm in vivo, using both silicone oil and deuterium dioxide (D2 O) immersion. We specifically characterize imaging depths, signal levels and spatial resolution. Our results show that both immersion media give similar performance in imaging depth and spatial resolution, while signal levels are slightly better with silicone oil immersion. We also demonstrate that local injection of fluorescent beads into the skin is a viable technique for spatial resolution characterization in vivo.
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Affiliation(s)
- Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Yi Pan
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Shen Tong
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Xinlin Chen
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Yuan Lu
- Department of Dermatology, The sixth Hospital of Shenzhen University (Nanshan Hospital), Shenzhen, China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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12
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Wang K, Pan Y, Tong S, Liang H, Qiu P. Deep-skin multiphoton microscopy of lymphatic vessels excited at the 1700-nm window in vivo. BIOMEDICAL OPTICS EXPRESS 2021; 12:6474-6484. [PMID: 34745750 PMCID: PMC8548020 DOI: 10.1364/boe.437482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 09/10/2021] [Accepted: 09/15/2021] [Indexed: 06/13/2023]
Abstract
Visualization of lymphatic vessels is key to the understanding of their structure, function, and dynamics. Multiphoton microscopy (MPM) is a potential technology for imaging lymphatic vessels, but tissue scattering prevents its deep penetration in skin. Here we demonstrate deep-skin MPM of the lymphatic vessels in mouse hindlimb in vivo, excited at the 1700 nm window. Our results show that with contrast provided by indocyanine green (ICG), 2-photon fluorescence (2PF) imaging enables noninvasive imaging of lymphatic vessels 300 μm below the skin surface, visualizing both its structure and contraction dynamics. Simultaneously acquired second-harmonic generation (SHG) and third-harmonic generation (THG) images visualize the local environment in which the lymphatic vessels reside. After removing the surface skin layer, 2PF and THG imaging visualize finer structures of the lymphatic vessels: most notably, the label-free THG imaging visualizes lymphatic valves and their open-and-close dynamics in real time. MPM excited at the 1700-nm window thus provides a promising technology for the study of lymphatic vessels.
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13
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Hofmann J, Keppler SJ. Tissue clearing and 3D imaging - putting immune cells into context. J Cell Sci 2021; 134:271108. [PMID: 34342351 DOI: 10.1242/jcs.258494] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A better understanding of cell-cell and cell-niche interactions is crucial to comprehend the complexity of inflammatory or pathophysiological scenarios such as tissue damage during viral infections, the tumour microenvironment and neuroinflammation. Optical clearing and 3D volumetric imaging of large tissue pieces or whole organs is a rapidly developing methodology that holds great promise for the in-depth study of cells in their natural surroundings. These methods have mostly been applied to image structural components such as endothelial cells and neuronal architecture. Recent work now highlights the possibility of studying immune cells in detail within their respective immune niches. This Review summarizes recent developments in tissue clearing methods and 3D imaging, with a focus on the localization and quantification of immune cells. We first provide background to the optical challenges involved and their solutions before discussing published protocols for tissue clearing, the limitations of 3D imaging of immune cells and image analysis. Furthermore, we highlight possible applications for tissue clearing and propose future developments for the analysis of immune cells within homeostatic or inflammatory immune niches.
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Affiliation(s)
- Julian Hofmann
- Institute for Clinical Chemistry and Pathobiochemistry, München rechts der Isar (MRI), Technical University Munich, 81675 Munich, Germany.,TranslaTUM, Center for Translational Cancer Research, Technical University Munich, 81675 Munich, Germany
| | - Selina J Keppler
- Institute for Clinical Chemistry and Pathobiochemistry, München rechts der Isar (MRI), Technical University Munich, 81675 Munich, Germany.,TranslaTUM, Center for Translational Cancer Research, Technical University Munich, 81675 Munich, Germany
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14
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Highly Efficient Nanosecond 1.7 μm Fiber Gas Raman Laser by H2-Filled Hollow-Core Photonic Crystal Fibers. CRYSTALS 2020. [DOI: 10.3390/cryst11010032] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We report here a high-power, highly efficient, wavelength-tunable nanosecond pulsed 1.7 μm fiber laser based on hydrogen-filled hollow-core photonic crystal fibers (HC-PCFs) by rotational stimulated Raman scattering. When a 9-meter-long HC-PCF filled with 30 bar hydrogen is pumped by a homemade tunable 1.5 μm pulsed fiber amplifier, the maximum average Stokes power of 3.3 W at 1705 nm is obtained with a slope efficiency of 84%, and the slope efficiency achieves the highest recorded value for 1.7 μm pulsed fiber lasers. When the pump pulse repetition frequency is 1.3 MHz with a pulse width of approximately 15 ns, the average output power is higher than 3 W over the whole wavelength tunable range from 1693 nm to 1705 nm, and the slope efficiency is higher than 80%. A steady-state theoretical model is used to achieve the maximum Stokes power in hydrogen-filled HC-PCFs, and the simulation results accord well with the experiments. This work presents a new opportunity for highly efficient tunable pulsed fiber lasers at the 1.7 μm band.
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15
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Chan RKY, He H, Ren YX, Lai CSW, Lam EY, Wong KKY. Axially resolved volumetric two-photon microscopy with an extended field of view using depth localization under mirrored Airy beams. OPTICS EXPRESS 2020; 28:39563-39573. [PMID: 33379502 DOI: 10.1364/oe.412453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
It is a great challenge in two-photon microscopy (2PM) to have a high volumetric imaging speed without sacrificing the spatial and temporal resolution in three dimensions (3D). The structure in 2PM images could be reconstructed with better spatial and temporal resolution by the proper choice of the data processing algorithm. Here, we propose a method to reconstruct 3D volume from 2D projections imaged by mirrored Airy beams. We verified that our approach can achieve high accuracy in 3D localization over a large axial range and is applicable to continuous and dense sample. The effective field of view after reconstruction is expanded. It is a promising technique for rapid volumetric 2PM with axial localization at high resolution.
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16
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He M, Wu D, Zhang Y, Fan X, Zhuang S, Yang W, Lin H, Qian J. Protein-Enhanced NIR-IIb Emission of Indocyanine Green for Functional Bioimaging. ACS APPLIED BIO MATERIALS 2020; 3:9126-9134. [PMID: 35019590 DOI: 10.1021/acsabm.0c01384] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fluorescence imaging performed in the 1500-1700 nm spectral range (labeled near-infrared IIb, NIR-IIb) promises high imaging contrast and spatial resolution for its little photon scattering effect and minimum autofluorescence. Though inorganic and organic probes have been developed for NIR-IIb bioimaging, most are in the preclinical stage, hampering further clinical application. Herein, we showed that indocyanine green (ICG), a US Food and Drug Administration (FDA)-approved agent, exhibited a remarkable amount of NIR-IIb emission when dissolved into different protein solutions, including human serum albumin, rat bile, and fetal bovine serum. We performed fluorescence imaging in the NIR-IIb window to visualize structures of the lymph system, extrahepatic biliary tract, and cerebrovascular. The results demonstrated that proteins promoted NIR-IIb emission of ICG in vivo and that NIR-IIb imaging with ICG preserved a higher signal-to-background ratio and spatial resolution compared with the conventional NIR-II fluorescence imaging. Our findings confirm that NIR-IIb fluorescence imaging can be successfully performed using the clinically approved agent ICG. Further clinical application in the NIR-IIb region would hopefully be carried out with appropriate ICG-protein solutions.
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Affiliation(s)
- Mubin He
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310058, China
| | - Di Wu
- Department of General Surgery, Sir Run-Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
| | - Yuhuang Zhang
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310058, China
| | - Xiaoxiao Fan
- Department of General Surgery, Sir Run-Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
| | - Siyi Zhuang
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou 310058, P. R. China
| | - Wei Yang
- Department of Biophysics, Zhejiang University School of Medicine, Hangzhou 310058, P. R. China
| | - Hui Lin
- Department of General Surgery, Sir Run-Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, China
| | - Jun Qian
- State Key Laboratory of Modern Optical Instrumentations, Centre for Optical and Electromagnetic Research, College of Optical Science and Engineering, International Research Center for Advanced Photonics, Zhejiang University, Hangzhou 310058, China
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17
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Deng X, He C, Cheng H, Li J, Lu Y, Qiu P, Wang K. Measurement of two-photon properties of indocyanine green in water and human plasma excited at the 1700-nm window. JOURNAL OF BIOPHOTONICS 2020; 13:e202000299. [PMID: 33026179 DOI: 10.1002/jbio.202000299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 06/11/2023]
Abstract
Indocyanine green (ICG) is a human compatible dye and is ideal for deep-tissue two-photon fluorescence (2PF) microscopy excited at the 1700-nm window in vivo. However, the two-photon excitation and emission properties of this dye remain unknown. Here we demonstrate measurement of the two-photon excitation and emission properties of ICG in both water and human plasma, using home-built two-photon action cross-sectional measurement and two-photon emission spectrum measurement systems. Our results show that excited from 1600 to 1800 nm, 2PF can be generated from ICG dissolved in both water and human plasma. The measured two-photon action cross-sectional ησ2 of ICG dissolved in human plasma is an order-of-magnitude larger than that dissolved in water. The measured two-photon emission spectrum overlaps with the one-photon emission spectrum for ICG dissolved in both human plasma and water. Our results will provide key two-photon parameters for the clinical use of ICG.
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Affiliation(s)
- Xiangquan Deng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Chen He
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Hui Cheng
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Jia Li
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Yuan Lu
- Department of Dermatology, The Sixth Hospital of Shenzhen University (Nanshan Hospital), Shenzhen, China
| | - Ping Qiu
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
| | - Ke Wang
- Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, China
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18
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Fan JL, Rivera JA, Sun W, Peterson J, Haeberle H, Rubin S, Ji N. High-speed volumetric two-photon fluorescence imaging of neurovascular dynamics. Nat Commun 2020; 11:6020. [PMID: 33243995 PMCID: PMC7693336 DOI: 10.1038/s41467-020-19851-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 10/13/2020] [Indexed: 02/02/2023] Open
Abstract
Understanding the structure and function of vasculature in the brain requires us to monitor distributed hemodynamics at high spatial and temporal resolution in three-dimensional (3D) volumes in vivo. Currently, a volumetric vasculature imaging method with sub-capillary spatial resolution and blood flow-resolving speed is lacking. Here, using two-photon laser scanning microscopy (TPLSM) with an axially extended Bessel focus, we capture volumetric hemodynamics in the awake mouse brain at a spatiotemporal resolution sufficient for measuring capillary size and blood flow. With Bessel TPLSM, the fluorescence signal of a vessel becomes proportional to its size, which enables convenient intensity-based analysis of vessel dilation and constriction dynamics in large volumes. We observe entrainment of vasodilation and vasoconstriction with pupil diameter and measure 3D blood flow at 99 volumes/second. Demonstrating high-throughput monitoring of hemodynamics in the awake brain, we expect Bessel TPLSM to make broad impacts on neurovasculature research.
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Affiliation(s)
- Jiang Lan Fan
- University of California, Berkeley, CA, USA.,University of California, San Francisco, CA, USA
| | - Jose A Rivera
- Department of Physics, University of California, Berkeley, CA, USA
| | - Wei Sun
- Thorlabs Imaging Systems, Sterling, VA, USA
| | | | | | - Sam Rubin
- Thorlabs Imaging Systems, Sterling, VA, USA.,LightPath Technologies Inc., Orlando, FL, USA
| | - Na Ji
- Department of Physics, University of California, Berkeley, CA, USA. .,Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA. .,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA. .,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
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19
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Qin Y, Batjargal O, Cromey B, Kieu K. All-fiber high-power 1700 nm femtosecond laser based on optical parametric chirped-pulse amplification. OPTICS EXPRESS 2020; 28:2317-2325. [PMID: 32121924 PMCID: PMC7053498 DOI: 10.1364/oe.384185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 01/04/2020] [Accepted: 01/06/2020] [Indexed: 05/09/2023]
Abstract
We present the design and construction of an all-fiber high-power optical parametric chirped-pulse amplifier working at 1700 nm, an important wavelength for bio-photonics and medical treatments. The laser delivers 1.42 W of output average power at 1700 nm, which corresponds to ∼40 nJ pulse energy. The pulse can be de-chirped with a conventional grating pair compressor to ∼450 fs. Furthermore, the laser has a stable performance with relative intensity noise typically below the -130 dBc/Hz level for the idler pulses at 1700 nm from 10kHz to 16.95 MHz, half of the laser repetition rate f/2.
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Affiliation(s)
- Yukun Qin
- College of Optical Sciences, University of Arizona, 1630 E. University Blvd, Tucson, Arizona 85721, USA
| | - Orkhongua Batjargal
- College of Optical Sciences, University of Arizona, 1630 E. University Blvd, Tucson, Arizona 85721, USA
| | - Benjamin Cromey
- College of Optical Sciences, University of Arizona, 1630 E. University Blvd, Tucson, Arizona 85721, USA
| | - Khanh Kieu
- College of Optical Sciences, University of Arizona, 1630 E. University Blvd, Tucson, Arizona 85721, USA
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