We perform resonant optical manipulation based on electronic transition resonance with an ultrashort pulsed laser.

Outcome：

2023
We performed optical trapping using an ultrashort laser pulse and found that the trapping effect was due to the increase in frictional resistance at the individual-liquid interface caused by optical absorption.

2022
We build an optical system for optical trapping with an ultrashort pulsed laser. As preliminary data, we observed the resonance effect by exciting the target particles.

Outcome：

2025
To avoid energy transfer, we built an Er:ZBLAN fiber laser to pump the Dy:ZBLAN fiber. The power of the amplified spontaneous emission increased with higher pump power, showing that energy transfer does not occur with the Er:ZBLAN fiber pump laser.

2024
We tried to build a 3 μm laser with a Dy:ZBLAN fiber. However, due to the energy transfer we were not able to obtain lasing at 3 μm.

2023
Opto-thermal manipulation with 3 μm mid-infrared Er:ZBLAN fiber laser
Roukuya Mamuti, Masaya Shimizu, Takao Fuji, and Tetsuhiro Kudo
Optics Express 32 (7), 12160-12171 (2024)

2022
We performed opto-thermal trapping of colloidal particles with a 3μm　Er-doped ZBLAN fiber laser. We started from the laser generation of 3μm continuous laser. Water has a strong absorption at 3μm in wavelength due to the O-H vibrational mode. We achieved the trapping with much lower laser power compared to our previous study with the 2 μm laser.

2021
We performed opto-thermal trapping of polystyrene particles with a 2 μm Tm-doped fiber laser. By using the 2 μm　laser, water is directly heated and it enables the trapping of the particles along the temperature gradient.

We conduct the novel optical manipulation with mid-infrared quantum cascade lasers for sorting particles according to their vibrational optical properties.

Outcome：

2025
Proposed method for label-free separation and infrared spectroscopy of carbonyl-containing micro-and nanoparticles using mid-infrared optical force
Yoshua Albert Darmawan, Taiki Yanagishima, Takao Fuji, Tetsuhiro Kudo
Analytical Chemistry 97 (27), 14658-14665 (2025)

2024
We successfully demonstrated the selective manipulation of PMMA (poly(methyl methacrylate)) and TPM (3-(trimethoxysilyl)propyl methacrylate), which contain the same carbonyl bonds but in different surrounding environments.

2023
Mid-Infrared Optical Force Chromatography of Microspheres Containing Siloxane Bonds
Yoshua Albert Darmawan, Takuma Goto, Taiki Yanagishima, Takao Fuji, and Tetsuhiro Kudo
The Journal of Physical Chemistry Letters 14 7306-7312 (2023), selected as Front Cover

2022
We present a mid-infrared optical force chromatography technique that enables precise sorting of microspheres based on their molecular vibrational properties using a mid-infrared quantum cascade laser. A variety of microspheres, including those composed of Si-O-Si bonds, can be separated in accordance with their absorbance values at that laser wavelength.

2021
Optical sorting of silica particles is demonstrated by exciting their vibrational mode with mid-infrared lasers.

2020
We prepared the optical system for mid-infrared optical manipulation.

It realizes chemical imaging, which has been difficult to achieve with conventional infrared light sources. Chemical imaging, which provides abundant chemical information, provides insight into the composition, characteristics, and structure of the observed object, and is expected to be applied to a wide range of fields, including chemistry, materials, environment, life science, and medicine.

Outcome：

2025
Generation of spectrally narrow, phase-stable pulse trains using a birefringent crystal array
Shuma Aoki, Nina Zambale Simon, Neil Irvin Cabello, Takao Fuji
Optics Express 34 (4), 5857-5869 (2026)

2024
Background-free mid-infrared absorption spectroscopy using sub-cycle pulses
Neil Irvin Cabello, Shinta Ozawa, Shota Kusama, Wei-Hong Huang, Chih-Wei Luo, Yue Zhao, and Takao Fuji
Optics Express 32 (16), 27670-27681 (2024)

2023
High-speed scanless entire bandwidth mid-infrared chemical imaging
Yue Zhao, Shota Kusama, Yuji Furutani, Wei-Hong Huang, Chih-Wei Luo, Takao Fuji
Nature Communications 14(1) 3929 (2023)

2022
High-speed full-field entire bandwidth mid-infrared chemical imaging
Yue Zhao, Shota Kusama, Yuji Furutani, Wei-Hong Huang, Chih-Wei Luo, and Takao Fuji
arXiv:2209.06372 [physics.optics]

Femtosecond pulsed laser oscillators and amplifiers using fluoride fiber as the laser medium, as well as solid-state laser amplifiers capable of generating even higher peak power pulses [Opt. Express 26 29460 (2018), Opt. Express 27 24499 (2019), Opt. Express 28 29918 (2020), Opt. Express 30 7332 (2022)].

Outcome：

2025
Sub-10-nJ femtosecond mode-locked oscillator based on a double-clad thulium-doped fluoride fiber
Nur Atikah binti Azali, Takao Fuji
Optics Express 34 (4), 7030-7037 (2026)

2024
Dispersion-managed mode-locked Tm:ZBLAN fiber lasers
Hiroki Kawase, Junya Takano, Rico Noguchi, and Takao Fuji
Optics Express 32 (22), 38960-38974 (2024)

2023
Dispersion-managed ultrafast laser based on thulium-doped ZBLAN fibers
Hiroki Kawase, Junya Takano, Takao Fuji
The 12th Asia-Pacific laser symposium

2022
Millijoule 265 fs Tm:YAP regenerative amplifier for driving ultrabroad band collinear mid-infrared optical parametric amplifiers
Seyed Ali Rezvani and Takao Fuji
Optics Express 30 (5), 7332-7339 (2022)

2020
Highly coherent multi-octave polarization-maintained supercontinuum generation solely based on ZBLAN fibers
Seyed Ali Rezvani, Kazuhiko Ogawa, and Takao Fuji
Optics Express 28 (20), 29918-29926 (2020)

2019
Generation and characterization of mid-infrared supercontinuum in polarization maintained ZBLAN fibers
S. A. Rezvani, Y. Nomura, K. Ogawa, and T. Fuji
Optics Express 27 (17), 24499-24511 (2019)

We have developed a new method to directly measure photoelectric field waveforms oscillating in a few femtoseconds [Nat. Commun. 4 2820 (2013)]. The method is much simpler than conventional methods using attosecond pulses and has the potential to be applied in a wide range of fields.

Outcome：

2025
Spectral phase interferometry for direct electric field reconstruction of chirped wavepackets generated from a tapered undulator
Takao Fuji, Takashi Tanaka, Tatsuo Kaneyasu, Yuichiro Kida, Kei Imamura, Satoshi Hashimoto, Aoi Gocho, Keisuke Kaneshima, Yoshihito Tanaka, Masahiro Katoh
Optics Letters 50 (24), 7604-7607(2025)

2024
分子科学研究所の極端紫外光放射光施設から発生する極端紫外光の1次光から3次光までの電場波形をSPIDER法によって測定することを試みた。また、兵庫県立大学が運用する放射光施設 NewSUBARUにおいて、チャープした波形をSPIDER法によって測定することに成功した。

2023
分子科学研究所の極端紫外光放射光施設から発生する極端紫外光の1次光から3次光までの電場波形をSPIDER法によって測定することを試みた。

2022
Spectral phase interferometry for direct electric-field reconstruction of synchrotron radiation
Takao Fuji, Tatsuo Kaneyasu, Masaki Fujimoto, Yasuaki Okano, Elham Salehi, Masahito Hosaka, Yoshifumi Takashima, Atsushi Mano, Yasumasa Hikosaka, Shin-ichi Wada, and Masahiro Katoh
Optica 10 302 (2023)
Optica 10 (2), 302-307 (2023)

We are developing fast infrared spectroscopy and femtosecond pump-probe spectroscopy using 7-femtosecond mid-infrared light pulses generated by the filamentation method [J. Opt. 17 094004 (2015)].

Outcome：

2024
Background-free mid-infrared absorption spectroscopy using sub-cycle pulses
Neil Irvin Cabello, Shinta Ozawa, Shota Kusama, Wei-Hong Huang, Chih-Wei Luo, Yue Zhao, and Takao Fuji
Optics Express 32 (16), 27670-27681 (2024)

2023
High-speed scanless entire bandwidth mid-infrared chemical imaging
Yue Zhao, Shota Kusama, Yuji Furutani, Wei-Hong Huang, Chih-Wei Luo, Takao Fuji
Nature Communications 14(1) 3929 (2023)

2022
サブサイクル中赤外光パルス光源の繰り返し周波数を10kHzから5kHzに変更することで、中赤外光パルスの強度が安定するようになった。この光源を利用して、これまでにない広帯域で高速な赤外ハイパースペクトルイメージングを行うことができた。

2020
Femtosecond time-evolution of mid-infrared spectral line shapes of Dirac fermions in topological insulators
Tien-Tien Yeh, Chien-Ming Tu, Wen-Hao Lin, Cheng-Maw Cheng, Wen-Yen Tzeng, Chen-Yu Chang, Hideto Shirai, Takao Fuji, Raman Sankar, Fang-Cheng Chou, Marin M. Gospodinov, Takayoshi Kobayashi, and Chih-Wei Luo
Scientific Reports 10, 9803 (2020)

We have successfully generated extremely short mid-infrared light pulses using a unique technique called filamentation method [Opt. Express 28 36527 (2020)]. We are conducting research and development to further improve the generation technique in order to make the optical pulses available to a wide range of scientific and industrial fields.

Outcome：

2025
Application of external electric field on laser filaments for ultrafast mid-infrared sub-cycle pulse stabilization
Neil Irvin Cabello, Shuto Nakamura, Yue Zhao, Takao fuji
CLEO/Europe-EQEC2025 2025年6月24日

2024
赤外光パルス発生箇所に高電圧をかけることで赤外光パルスの発生効率と安定性が向上した。

2023
Sub-cycle mid-infrared pulse: generation and applications
Takao Fuji
Frontiers of ultrafast science: From fundamentals to applications
Invited talk

2022
繰り返し周波数を10kHzから5kHzに変更することで、中赤外光パルスが安定するようになった。この光源を利用して、これまでにない高速な赤外ハイパースペクトルイメージングを行うことができた。

2020
Generation of sub-half-cycle 10 µm pulses through filamentation at kilohertz repetition rates
Wei-Hong Huang, Yue Zhao, Shota Kusama, Fumitoshi Kumaki, Chih-Wei Luo, and Takao Fuji
Optics Express 28 (24), 36527-36543 (2020)

Develop a new fiber laser suitable for multiphoton microscopy.

Outcome：

2025
Watt-level ultrafast 1.75㎛ laser system based on thulium-doped core and terbium-doped cladding fluoride fibers
Dina Grace Banguilan, Yuto Iye, Kazuhiko Ogawa, Eiji Kajikawa, Takao Fuji
Japanese Journal of Applied Physics 65, 052003 (2026)

2024
Watt-level femtosecond praseodymium-doped fluoride fiber amplifier at 1300nm
Junya Takano, Tatsuki Yamada, and Takao Fuji
Optics Express 33 (5), 10555-10562 (2025)

2023
Chirped pulse amplification based on praseodymium-doped fluoride fibers
Koki Yamaizumi, Fumihiro Hondo, and Takao Fuji
Optics Express 31 (10), 16127-16132 (2023)

2022
In vivo three- and four-photon fluorescence microscopy using a 1.8 µm femtosecond fiber laser system
Hideji Murakoshi, Hiromi H. Ueda, Ryuichiro Goto, Kosuke Hamada, Yutaro Nagasawa, and Takao Fuji
Biomedical Optics Express 14 (1), 326-334 (2023)

2020
Short-wavelength, ultrafast thulium-doped fiber laser system for three-photon microscopy
Yutaka Nomura, Hideji Murakosh, and Takao Fuji
OSA Continuum 3 (6), 1428-1435 (2020)

Outcome：

2025
We have successfully achieved optical trapping of microparticles using a focused mid-infrared beam. Our results clarify that the trapping stiffness, which serves as a value of the optical trapping force, is dependent on the laser wavelength. We will continue these experiments in the next year.

2024
We demonstrated the experiment of mid-infrared optical tweezers. We build the optical microscope with mid-infrared laser. Under certain condition, the target particles were assembled at the glass solution interface by the mid-infrared laser.

中赤外領域における局在電場を利用しナノ粒子安定的に光捕捉することが目的である。

Outcome：

2025
金属ナノ構造体の作製も開始した。概ねFDTDシミュレーションに似たナノ構造体を電子線描画装置等を用いて作製することができた。グラフェンのナノ構造体作製に関しては、クリーンルームにおいて作製を開始している。

2024
FDTDシミュレーションを用いて、ナノ粒子捕捉へ向けたグラフェンナノ構造体の設計を行った。