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Morichika I, Tsusaka H, Ashihara S. Generation of High-Lying Vibrational States in Carbon Dioxide through Coherent Ladder Climbing. J Phys Chem Lett 2024; 15:4662-4668. [PMID: 38647557 PMCID: PMC11073050 DOI: 10.1021/acs.jpclett.4c00646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/17/2024] [Accepted: 04/18/2024] [Indexed: 04/25/2024]
Abstract
Mid-infrared laser excitation of molecules into high-lying vibrational states offers a novel route to realize controlled ground-state chemistry. Here we successfully demonstrate vibrational ladder climbing in the antisymmetric stretch of CO2 in the condensed phase by using intense down-chirped mid-infrared pulses. Spectrally resolved pump-probe measurements directly observe excited-state absorptions attributed to vibrational populations up to the v = 9 state, whose corresponding energy of 2.5 eV is 46% of the dissociation energy. By the use of global fitting analysis, important spectroscopic parameters in the high-lying vibrational states, such as transition frequencies and relaxation times, are quantitatively characterized. Remarkably, our analysis shows that 40% of the molecules are excited above the typical activation barriers in the metal-catalyzed CO2 conversions. These results not only demonstrate the promising ability of infrared excitation to produce elevated vibrational states but also represent a significant step toward accelerating CO2 conversions and other chemical processes via mode-specific vibrational excitation.
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Affiliation(s)
- Ikki Morichika
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Hiroki Tsusaka
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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2
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Ikegami Y, Duenki T, Arakaki I, Sakai R, Osaki T, Ashihara S, Furushima T, Ikeuchi Y. A simple and inexpensive laser dissection of fasciculated axons from motor nerve organoids. Front Bioeng Biotechnol 2024; 12:1259138. [PMID: 38347914 PMCID: PMC10859526 DOI: 10.3389/fbioe.2024.1259138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2023] [Accepted: 01/15/2024] [Indexed: 02/15/2024] Open
Abstract
Motor nerve organoids could be generated by culturing a spheroid of motor neurons differentiated from human induced pluripotent stem (iPS) cells within a polydimethylsiloxane (PDMS) chip which guides direction and fasciculation of axons extended from the spheroid. To isolate axon bundles from motor nerve organoids, we developed a rapid laser dissection method based on localized photothermal combustion. By illuminating a blue laser on a black mark on the culture device using a dry-erase marker, we induced highly localized heating near the axon bundles. Moving the laser enabled spatial control over the local heating and severing of axon bundles. This laser dissection requires a black mark, as other colors did not produce the same localized heating effect. A CO2 laser destroyed the tissue and the device and could not be used. With this simple, economical laser dissection technique, we could rapidly collect abundant pure axon samples from motor nerve organoids for biochemical analysis. Extracted axonal proteins and RNA were indistinguishable from manual dissection. This method facilitates efficient axon isolation for further analyses.
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Affiliation(s)
- Yasuhiro Ikegami
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
| | - Tomoya Duenki
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
- Laboratory for Integrated Micro Mechatronic Systems, National Center for Scientific Research-Institute of Industrial Science (LIMMS/CNRS-IIS), The University of Tokyo, Tokyo, Japan
| | - Ikuma Arakaki
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Ryo Sakai
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Tatsuya Osaki
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | | | - Yoshiho Ikeuchi
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
- Institute for AI and Beyond, The University of Tokyo, Tokyo, Japan
- Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan
- Laboratory for Integrated Micro Mechatronic Systems, National Center for Scientific Research-Institute of Industrial Science (LIMMS/CNRS-IIS), The University of Tokyo, Tokyo, Japan
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3
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Song W, Fujiwara K, Zhang Z, Morichika I, Ashihara S. Broadband dispersion spectroscopy using interferometric phase modulation under background light suppression. Opt Lett 2023; 48:4257-4260. [PMID: 37582006 DOI: 10.1364/ol.496288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/21/2023] [Indexed: 08/17/2023]
Abstract
This Letter presents a dispersion spectroscopy method that achieves simultaneous detection of molecular vibrational dispersion over a broad spectral range. The method is implemented with an infrared mode-locked laser, a dispersion-compensated Michelson interferometer, and a multichannel detector. Synchronous detection under interferometric phase modulation near the destructive interference condition is employed to achieve a high signal-to-noise ratio. We successfully demonstrate the method by measuring the dispersion of carbon monoxide gas, achieving a noise-equivalent dispersion of 1.3 × 10-8 cm and a corresponding noise-equivalent absorbance of 6.5 × 10-4 with a measurement time of 2.2 s.
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4
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Okazaki D, Song W, Morichika I, Ashihara S. Mode-locked laser oscillation with spectral peaks at molecular rovibrational transition lines. Opt Lett 2022; 47:6077-6080. [PMID: 37219176 DOI: 10.1364/ol.477555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 10/31/2022] [Indexed: 05/24/2023]
Abstract
We demonstrate spectral peak formation in a mode-locked solid-state laser that contains a gas cell inside the cavity. Symmetric spectral peaks appear in the course of sequential spectral shaping through resonant interaction with molecular rovibrational transitions and nonlinear phase modulation in the gain medium. The spectral peak formation is explained as that narrowband molecular emissions triggered by an impulsive rovibrational excitation are superposed on the broadband spectrum of the soliton pulse by constructive interference. The demonstrated laser, which exhibits comb-like spectral peaks at molecular resonances, potentially provides novel tools for ultrasensitive molecular detection, vibration-mediated chemical reaction control, and infrared frequency standards.
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5
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Song W, Okazaki D, Morichika I, Ashihara S. Broadband background-free vibrational spectroscopy using a mode-locked Cr:ZnS laser. Opt Express 2022; 30:38674-38683. [PMID: 36258426 DOI: 10.1364/oe.470893] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
We demonstrate high-sensitivity vibrational absorption spectroscopy in the 2-micron wavelength range by using a mode-locked Cr:ZnS laser. Interferometric subtraction and multichannel detection across the broad laser spectrum realize simultaneous background-free detection of multiple vibrational modes over a spectral span of >380 cm-1. Importantly, we achieve detection of small absorbance on the order of 10-4, which is well below the detection limit of conventional absorption spectroscopy set by the detector dynamic range. The results indicate the promising potential of the background-free method for ultrasensitive and rapid detection of trace gases and chemicals.
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6
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Bu X, Okazaki D, Ashihara S. Inherent intensity noise suppression in a mode-locked polycrystalline Cr:ZnS oscillator. Opt Express 2022; 30:8517-8525. [PMID: 35299303 DOI: 10.1364/oe.453382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 02/18/2022] [Indexed: 06/14/2023]
Abstract
We developed a diode-pumped, mode-locked polycrystalline Cr:ZnS oscillator using single-walled carbon nanotubes as a saturable absorber. The oscillator exhibits self-start mode-locking operation, generating sub-100 fs pulses with an average power of 300 mW. We found a unique feature in which the intensity noise originating from relaxation oscillation is suppressed by inherent second harmonic generation in polycrystalline Cr:ZnS. The observed noise suppression is reproduced by a theoretical model that includes an instantaneous nonlinear loss.
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Kugel T, Okazaki D, Arai K, Ashihara S. Direct electric-field reconstruction of few-cycle mid-infrared pulses in the nanojoule energy range. Appl Opt 2022; 61:1076-1081. [PMID: 35201081 DOI: 10.1364/ao.446473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Amid the increasing potential of ultrafast mid-infrared (mid-IR) laser sources based on transition metal doped chalcogenides such as Cr:ZnS, Cr:ZnSe, and Fe:ZnSe lasers, there is a need for direct and sensitive characterization of mid-IR mode-locked laser pulses that work in the nanojoule energy range. We developed a two-dimensional spectral shearing interferometry (2DSI) setup to successfully demonstrate the direct electric-field reconstruction of Cr:ZnS mode-locked laser pulses with a central wavelength of 2.3 µm, temporal duration of 30.3 fs, and energies of 3 nJ. The reconstructed electric field is in reasonable agreement with an independently measured intensity autocorrelation trace, and the quantitative reliability of the 2DSI measurement is verified from a material dispersion evaluation. The presented implementation of 2DSI, including a choice of nonlinear crystal as well as the use of high-throughput dispersive elements and a high signal-to-noise ratio near-IR spectrometer, would benefit future development of ultrafast mid-IR lasers and their applications.
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Abstract
Vibrational strong coupling (VSC) between a vacuum field and molecules in a cavity offers promising applications in cavity-modified chemical reactions and ultrasensitive vibrational spectroscopy. At present, in order to realize VSC, bulky microcavities with large mode volume are utilized, which limits their potential applications at the nanoscale. Here, we report on the experimental realization of strong coupling between molecular vibrations and infrared photons confined within a deeply subwavelength nanogap patch antenna cavity. Our system exhibits a characteristic anticrossing dispersion, indicating a Rabi splitting of 108 cm-1 at the single resonator level with excellent angular insensitivity. The numerical simulations and theoretical analyses quantitatively reveal that the strength of coupling depends on the cavity field-molecule overlap integral and the image charge effect. VSC at the single nanogap patch antenna level paves the way for molecular-scale chemistry, ultrasensitive biosensors, and the development of ultralow-power all-optical devices in the mid-infrared spectral range.
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Affiliation(s)
- Govind Dayal
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-Ku, Tokyo 153-8505, Japan
| | - Ikki Morichika
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-Ku, Tokyo 153-8505, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-Ku, Tokyo 153-8505, Japan
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9
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Okazaki D, Morichika I, Arai H, Kauppinen E, Zhang Q, Anisimov A, Varjos I, Chiashi S, Maruyama S, Ashihara S. Ultrafast saturable absorption of large-diameter single-walled carbon nanotubes for passive mode locking in the mid-infrared. Opt Express 2020; 28:19997-20006. [PMID: 32680068 DOI: 10.1364/oe.395962] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 06/09/2020] [Indexed: 06/11/2023]
Abstract
We study the saturable absorption properties of single-walled carbon nanotubes (SWCNTs) with a large diameter of 2.2 nm and the corresponding exciton resonance at a wavelength of 2.4 µm. At resonant excitation, a large modulation depth of approximately 30 % and a small saturation fluence of a few tens of µJ/cm2 are evaluated. The temporal response is characterized by an instantaneous rise and a subpicosecond recovery. We also utilize the SWCNTs to realize sub-50 fs, self-start mode locking in a Cr:ZnS laser, revealing that the film thickness is an important parameter that affects the possible pulse energy and duration. The results prove that semiconductor SWCNTs with tailored diameters exceeding 2 nm are useful for passive mode locking in the mid-infrared range.
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10
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Morichika I, Murata K, Sakurai A, Ishii K, Ashihara S. Molecular ground-state dissociation in the condensed phase employing plasmonic field enhancement of chirped mid-infrared pulses. Nat Commun 2019; 10:3893. [PMID: 31467268 PMCID: PMC6715752 DOI: 10.1038/s41467-019-11902-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 08/09/2019] [Indexed: 01/22/2023] Open
Abstract
Selective bond cleavage via vibrational excitation is the key to active control over molecular reactions. Despite its great potential, the practical implementation in condensed phases have been hampered to date by poor excitation efficiency due to fast vibrational relaxation. Here we demonstrate vibrationally mediated, condensed-phase molecular dissociation by employing intense plasmonic near-fields of temporally-shaped mid-infrared (mid-IR) pulses. Both down-chirping and substantial field enhancement contribute to efficient ladder climbing of the carbonyl stretch vibration of W(CO)6 in n-hexane solution and to the resulting CO dissociation. We observe an absorption band emerging with laser irradiation at the excitation beam area, which indicates that the dissociation is followed by adsorption onto metal surfaces. This successful demonstration proves that the combination of ultrafast optics and nano-plasmonics in the mid-IR range is useful for mode-selective vibrational ladder climbing, paving the way toward controlled ground-state chemistry.
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Affiliation(s)
- Ikki Morichika
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Kei Murata
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Atsunori Sakurai
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Kazuyuki Ishii
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 153-8505, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, 153-8505, Japan.
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11
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Okazaki D, Arai H, Anisimov A, Kauppinen EI, Chiashi S, Maruyama S, Saito N, Ashihara S. Self-starting mode-locked Cr:ZnS laser using single-walled carbon nanotubes with resonant absorption at 2.4 μm. Opt Lett 2019; 44:1750-1753. [PMID: 30933138 DOI: 10.1364/ol.44.001750] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 03/08/2019] [Indexed: 06/09/2023]
Abstract
We develop a mode-locked Cr:ZnS polycrystalline laser using single-walled carbon nanotubes (SWCNTs) that have resonant absorption at the wavelength of 2.4 μm. The laser generates ultrashort pulses of 49 fs duration, a 2.4 μm center wavelength, and a 9.2 THz (176 nm) spectral span at a repetition rate of 76 MHz. We also confirm self-starting of the mode-locked operation. SWCNTs, if appropriately controlled in terms of their diameters, prove to be useful as ultrafast saturable absorbers in the mid-infrared region.
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12
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Abstract
We demonstrate surface-enhanced ultrafast vibrational spectroscopy employing periodic arrays of infrared-resonant gold nanoantennas. The antenna-enhancements of molecular vibrational responses are analytically formulated with a simple coupled-dipole model, and the linear/nonlinear local signal enhancements are evaluated to be ~104and 107, respectively.
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13
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Imasaka K, Kaji T, Shimura T, Ashihara S. Antenna-enhanced high harmonic generation in a wide-bandgap semiconductor ZnO. EPJ Web Conf 2019. [DOI: 10.1051/epjconf/201920502024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We demonstrate high harmonic generation (HHG) into deep-UV range in a ZnO single crystal with resonant nanoantennas. Non-perturbative HHG is successfully induced by optical excitation of as low as 20 GW/cm2. The spectral selection rule is found to reflect crystal symmetry, suggesting the possibility of nano-scaled EUV sources and band-structure reconstruction.
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14
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Sakurai A, Ando K, Ashihara S. Ultrafast Proton/Deuteron Dynamics in Solid Oxide Observed with Infrared Pump-Probe Spectroscopy. EPJ Web Conf 2019. [DOI: 10.1051/epjconf/201920504024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We performed pump-probe spectroscopy on OD stretching mode in KTaO3 to explore how a proton/deuteron interacts with the surroundings. We identified the potential anharmonicity and phonon modes which interact with a proton/deuteron, considering the temperature effect.
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15
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Sakurai A, Ando K, Ashihara S. Ultrafast proton/deuteron dynamics in KTaO 3 observed with infrared pump-probe spectroscopy: Toward understanding of proton conduction mechanism in solid oxides. J Chem Phys 2018; 149:104502. [DOI: 10.1063/1.5040063] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Atsunori Sakurai
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
| | - Koji Ando
- Department of Information and Sciences, Tokyo Woman’s Christian University, 2-6-1 Zenpukuji, Suginami, Tokyo 167-8585, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8505, Japan
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16
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Imasaka K, Kaji T, Shimura T, Ashihara S. Antenna-enhanced high harmonic generation in a wide-bandgap semiconductor ZnO. Opt Express 2018; 26:21364-21374. [PMID: 30119439 DOI: 10.1364/oe.26.021364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 07/20/2018] [Indexed: 06/08/2023]
Abstract
High harmonic generation (HHG) in solids has great potential for coherent extreme ultraviolet (EUV) sources, all-optical band-structure reconstruction, and electron dynamics metrology. Solid HHG driven by plasmonic near-fields will open a new paradigm, enabling high repetition-rate HHG with a compact laser, HHG manipulation with meta-surfaces, and precise control over carrier trajectory. In this paper, we demonstrate antenna-enhanced HHG in a wide-bandgap semiconductor ZnO. By exploiting gold nano-antennas resonating at the driver wavelength of 2 μm, we successfully trigger HHG at input intensity of ~0.02 TW/cm2 and observe harmonic radiations up to 9th-order. Orders-of-magnitude enhanced conversion efficiency at the hot-spots brings about ten-fold enhancement in the total yield. The spectral selection rule is found to reflect crystal symmetry, suggesting the possibility of nano-scaled EUV sources and band-structure reconstruction.
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17
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Kaneshima K, Shinohara Y, Takeuchi K, Ishii N, Imasaka K, Kaji T, Ashihara S, Ishikawa KL, Itatani J. Polarization-Resolved Study of High Harmonics from Bulk Semiconductors. Phys Rev Lett 2018; 120:243903. [PMID: 29957005 DOI: 10.1103/physrevlett.120.243903] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Indexed: 06/08/2023]
Abstract
The polarization property of high harmonics from gallium selenide is investigated using linearly polarized midinfrared laser pulses. With a high electric field, the perpendicular polarization component of the odd harmonics emerges, which is not present with a low electric field and cannot be explained by the perturbative nonlinear optics. A two-dimensional single-band model is developed to show that the anisotropic curvature of an energy band of solids, which is pronounced in an outer part of the Brillouin zone, induces the generation of the perpendicular odd harmonics. This model is validated by three-dimensional quantum mechanical simulations, which reproduce the orientation dependence of the odd-order harmonics. The quantum mechanical simulations also reveal that the odd- and even-order harmonics are produced predominantly by the intraband current and interband polarization, respectively. These experimental and theoretical demonstrations clearly show a strong link between the band structure of a solid and the polarization property of the odd-order harmonics.
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Affiliation(s)
- Keisuke Kaneshima
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Yasushi Shinohara
- Photon Science Center, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kengo Takeuchi
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Nobuhisa Ishii
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
| | - Kotaro Imasaka
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Tomohiro Kaji
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Satoshi Ashihara
- Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
| | - Kenichi L Ishikawa
- Photon Science Center, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Nuclear Engineering and Management, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Jiro Itatani
- The Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
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18
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Kusa F, Morichika I, Takegami A, Ashihara S. Enhanced ultrafast infrared spectroscopy using coupled nanoantenna arrays. Opt Express 2017; 25:12896-12907. [PMID: 28786641 DOI: 10.1364/oe.25.012896] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 05/15/2017] [Indexed: 06/07/2023]
Abstract
Surface-enhanced nonlinear vibrational spectroscopy using periodic gold nanoantenna arrays is demonstrated. The dipolar coupling among arrayed nanoantennas is shown to have striking impact on near-field enhancements of femtosecond pulsed-fields and on nonlinear signal enhancements. The condition near the collective-resonance achieves averaged signal enhancement of 850 times and local signal enhancement of 1.8 × 106 times, substantially reducing the required pump energy from micro-joule to nano-joule level. The scheme is useful for characterizing structure and dynamics of minute-volume molecular samples, monolayers, and interfaces, as well as paves the way to nonlinear vibrational spectroscopy with compact light sources of oscillator-level.
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Abstract
We achieved efficient spectral broadening for mid-IR pulses of few-microjoule energy. The spectral bandwidth of the femtosecond pulses at the center wavelength of 5000 nm increased from 540 nm to 2060 nm (from 220 to 910 cm(-1) in frequency) by nonlinear propagation in a gallium arsenide single crystal. The spectral broadening was accompanied by nonlinear absorption loss of 25%. The demonstrated scheme should be available at any operation wavelength within the material transparency range and provides a useful tool in nonlinear vibrational spectroscopy.
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Affiliation(s)
- S Ashihara
- Department of Applied Physics, Tokyo University of Agriculture and Technology,2-24-16 Nakacho, Koganei, Tokyo 184-8588 Japan.
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22
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Zeng X, Ashihara S, Wang Z, Wang T, Chen Y, Cha M. Excitation of two-colored temporal solitons in a segmented quasi-phase-matching structure. Opt Express 2009; 17:16877-16884. [PMID: 19770904 DOI: 10.1364/oe.17.016877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We conducted a numerical study on the excitation of a two-colored temporal soliton in a segmented quasi-phase-matching (QPM) structure. The device has three parts: a periodic QPM grating for second-harmonic generation, a single domain for phase shift, and a periodic QPM grating for soliton evolution. The second harmonic pulse generated in the first grating works as a seed in the cascaded up-and-down conversions in the second grating. The numerical results showed that the second harmonic seeding enables the excitation of soliton pulses with an improved spatio-temporal intensity profile in a broad bandwidth of the wave-vector mismatch.
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Affiliation(s)
- Xianglong Zeng
- Key Laboratory of Specialty Fiber Optics and Optical Access Networks, SCIE, Shanghai University, Shanghai 200072, China.
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23
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Hayashi Y, Ashihara S, Shimura T, Kuroda K. Simultaneous separation of polydisperse particles using an asymmetric nonperiodic optical stripe pattern. Appl Opt 2009; 48:1543-1552. [PMID: 19277088 DOI: 10.1364/ao.48.001543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We present simultaneous separation of polydisperse particles driven by an optical gradient force in the absence of microfluidic flow. The separation mechanism involves particle-size dependence of the potential landscape generated by a one-dimensional asymmetric optical stripe pattern. The outcome is that the particles align in different stacks according to their sizes. The dynamics of Brownian particles inside the optical potential landscapes are investigated theoretically and experimentally for various optical intensities and particle sizes. By introducing sequential changes in the optical profile, we also show that this technique allows semipassive arrangement of particles in arbitrary configurations.
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Affiliation(s)
- Yasuyuki Hayashi
- Institute of Industrial Science, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan
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24
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Kozich V, Dreyer J, Ashihara S, Werncke W, Elsaesser T. Mode-selective O-H stretching relaxation in a hydrogen bond studied by ultrafast vibrational spectroscopy. J Chem Phys 2007; 125:074504. [PMID: 16942348 DOI: 10.1063/1.2219111] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The ultrafast relaxation of the excited O-H stretching vibration is studied by ultrafast infrared-pump/infrared-probe and infrared-pump/Raman-probe spectroscopy. We demonstrate a 200 fs lifetime of the hydrogen-bonded O-H stretching mode in 2-(2'-hydroxy-5'-methyl-phenyl)benzotriazole (TINUVIN P). O-H stretching relaxation occurs through a few major channels that all involve combination and overtone bands of modes with considerable in-plane O-H bending character. In particular, the mode, which contains the largest O-H bending contribution, plays a prominent role for primary processes of intramolecular vibrational energy redistribution. Theoretical calculations of vibrational energy transfer rates based on a Fermi golden rule approach account for the experimental findings.
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Affiliation(s)
- Valeri Kozich
- Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Strasse 2A, D-12489 Berlin, Germany
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Ashihara S, Huse N, Espagne A, Nibbering ETJ, Elsaesser T. Ultrafast Structural Dynamics of Water Induced by Dissipation of Vibrational Energy. J Phys Chem A 2007; 111:743-6. [PMID: 17266211 DOI: 10.1021/jp0676538] [Citation(s) in RCA: 179] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the liquid phase, water molecules form a disordered fluctuating network of intermolecular hydrogen bonds. Using both inter- and intramolecular vibrations as structural probes in ultrafast infrared spectroscopy, we demonstrate a two-stage structural response of this network to energy disposal: vibrational energy from individually excited water molecules is transferred to intermolecular modes, resulting in a sub-100 fs nuclear rearrangement that leaves the local hydrogen bonds weakened but unbroken. Subsequent energy delocalization over many molecules occurs on an approximately 1 ps time scale and is connected with the breaking of hydrogen bonds, resulting in a macroscopically heated liquid.
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Affiliation(s)
- Satoshi Ashihara
- Max Born Institut für Nichtlineare Optik und Kurzzeitspektroskopie, 12489 Berlin, Germany
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Zeng X, Ashihara S, Fujioka N, Shimura T, Kuroda K. Adiabatic compression of quadratic temporal solitons in aperiodic quasi-phase-matching gratings. Opt Express 2006; 14:9358-9370. [PMID: 19529320 DOI: 10.1364/oe.14.009358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
We numerically show that it is possible to achieve adiabatic compression of femtosecond quadratic solitons in aperiodically poled lithium niobate device. Two-colored solitons of the fundamental wavelength of 1560 nm can be adiabatically shaped by using group-velocity matching schemes available in quasi-phase-matching (QPM) devices. We investigate the performance of the adiabatic compression based on two different group-velocity matching schemes: type-I (e: o + o) collinear QPM geometry and type-0 (e: e + e) non-collinear QPM geometry. Two-colored temporal solitons with pulse duration of 35 fs are generated without visible pedestals from 100-fs fundamental pulse. We also show that walking solitons with shorter pulse durations are adiabatically excited under small group-velocity mismatch condition. The walking solitons experience deceleration or acceleration during compression, depending on the sign of the groupvelocity- mismatch. The demonstrated adiabatic pulse shaping is useful for generation of shorter pulses with clean temporal profiles, efficient femtosecond second harmonic generation and group-velocity control.
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Fujioka N, Ashihara S, Ono H, Shimura T, Kuroda K. Group-velocity-mismatch compensation in cascaded third-harmonic generation with two-dimensional quasi-phase-matching gratings. Opt Lett 2006; 31:2780-2. [PMID: 16936890 DOI: 10.1364/ol.31.002780] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
A novel scheme to achieve broadband cascaded third-harmonic generation by use of two-dimensional quasi-phase-matching gratings is proposed. Intrinsic group-velocity mismatch is compensated by the pulse front tilt in noncollinear interaction geometry. The presented scheme enables broadband third-harmonic generation in a single device of long interaction length, which reduces the operation intensity dramatically.
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Affiliation(s)
- Nobuhide Fujioka
- Institute of Industrial Science, The University of Tokyo, Japan.
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Ashihara S, Huse N, Espagne A, Nibbering E, Elsaesser T. Vibrational couplings and ultrafast relaxation of the O–H bending mode in liquid H2O. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.04.051] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Ashihara S, Shimura T, Kuroda K, Yu NE, Kurimura S, Kitamura K, Ro JH, Cha M, Taira T. Group-velocity-matched cascaded quadratic nonlinearities of femtosecond pulses in periodically poled MgO:LiNbO3. Opt Lett 2003; 28:1442-1444. [PMID: 12943085 DOI: 10.1364/ol.28.001442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Large nonlinear phase shifts were generated with femtosecond pulses at 1560 nm through cascaded quadratic interactions in periodically poled MgO-doped LiNbO3. The off-diagonal component of the nonlinear coefficient was utilized for simultaneous quasi phase matching and group-velocity matching. The effective nonlinear refractive index was varied from -2.9 x 10(-14) to +3.3 x 10(-14) cm2/W by tuning the phase-mismatch conditions.
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Affiliation(s)
- Satoshi Ashihara
- Institute of Industrial Science, University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo 153-8505, Japan.
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