A5020406557- Advanced Fiber Laser Technologies
- Solid State Laser Technologies
- Photonic Crystal and Fiber Optics
- Photorefractive and Nonlinear Optics
- Laser-Matter Interactions and Applications
- Optical Network Technologies
- Advanced Fiber Optic Sensors
- Luminescence Properties of Advanced Materials
- Laser-induced spectroscopy and plasma
- Laser Design and Applications
- Advanced Photonic Communication Systems
- Laser Material Processing Techniques
- Laser-Plasma Interactions and Diagnostics
- Diamond and Carbon-based Materials Research
- Photonic and Optical Devices
- Optical Wireless Communication Technologies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Advanced Machining and Optimization Techniques
- solar cell performance optimization
- Ocular and Laser Science Research
- Particle Detector Development and Performance
- Electrohydrodynamics and Fluid Dynamics
- Impact of Light on Environment and Health
- Fluid Dynamics Simulations and Interactions
- Muon and positron interactions and applications
Ibaraki University
2006-2021
Hitachi (Japan)
2004-2014
RIKEN
1993-2013
Japan Science and Technology Agency
2001-2004
Hokkaido University
2000-2002
Hokkaido University of Science
2000
Keio University
1994-1996
Institute of Physical and Organic Chemistry
1996
For many fiber applications, the Brillouin gain spectrum (BGS) contains important information including frequency shift, spontaneous linewidth, and coefficient. This paper is first, to best of our knowledge, present an accurate numerical simulation BGS in single-mode fibers. The simulated measured were good agreement. Through repeated simulations, we revealed a tendency peak coefficient that determines stimulated scattering threshold.
Femtosecond infrared pulses from an ultrashort high-peak-power Ti:sapphire laser were successfully utilized for ablation of polymer films such as polytetrafluoroethylene, tetrafluoro- ethylene-hexafluoropropylene copolymer, and polyimide. Good agreement between experimental data calculations a model suggested that simultaneous absorption three photons polyimide five tetrafluoroethylene-hexafluoropropylene copolymer predominated over the other absorptive channels multiphoton was induced efficiently.
We experimentally demonstrated a dual-wavelength independently mode-locked Yb:YAG ceramic laser in single cavity. Dual-wavelength mode locking at 1033.6 and 1047.6 nm was operated simultaneously one beam. Each pulse width measured to be approximately 380 fs using an autocorrelator. The spectral widths were 4.50 centered 3.08 nm. To the best of our knowledge, this is first achieved Yb-doped solid-state lasers.
Wave-propagation equations, including effectively the second derivative in time under condition of a small difference between group and phase velocities first position /spl xi/ velocity coordinate, are derived based on slowly evolving wave approximation. These can describe ultrabroadband optical pulse propagation with not only self-phase modulation (SPM), but also induced-phase (IPM) monocycle regime fiber. It is shown that linear dispersion effects be rigorously included numerical...
We have demonstrated a carrier-envelope phase (CEP) stabilized chirped-pulse amplification (CPA) system employing grating-based pulse stretcher and compressor regenerative amplifier for the first time. In addition to stabilizing offset of laser oscillator, new selection method referenced beat signal was introduced. The pulse-selection is more robust against fluctuations than simple pulse-clock dividing method. observed stable fringe in self-referencing spectrum interferometry amplified...
A diode-pumped passively mode-locked Yb:YAG ceramic laser was demonstrated. 417 and 286 fs pulses with average powers of 250 25 mW were obtained at 1030 nm using 1 0.1% output couplers, respectively. 233 an power 20 also a center wavelength 1048.3 coupler. To the best our knowledge, this is first demonstration laser.
The pulse timing of a mode-locked Er-doped fiber laser was stabilized to reference train from Cr:forsterite by all-optical passive synchronization scheme. pulses were injected into ring cavity the using 1.3-1.5 mum wavelength-division multiplexer. spectral shift induced cross-phase modulation between copropagating two-color realizes self-synchronization due intracavity group-delay dispersion. rms integration jitter and 3.7 fs in Fourier frequency range 1 Hz 100 kHz.
Conventionally, the beam-propagation method for solving generalized nonlinear Schro/spl uml/dinger equation, including slowly varying envelope approximation, has been used to describe ultrashort-laser-pulse propagation in an optical fiber. However, if pulse duration approaches cycle regime (<10 fs), this approximation becomes invalid. Then, it necessary use finite-difference time-domain (FDTD) Maxwell equation with least approximation. In order both experimentally and numerically investigate...
A diode-end-pumped Yb3+:Y3Al5O12 (Yb:YAG) ceramic laser with a broad tunability was demonstrated. Continuous spectral range of 104.52 nm from 994.35 to 1098.87 for T=1% at maximum output power 1.4 W and 118.31 992.52 1110.83 T=0.1% 0.16 also obtained room temperature. To the best our knowledge, this is broadest reported Yb:YAG laser.
A diode-end-pumped Yb3+:Y3Al5O12 (Yb:YAG) ceramic laser with high efficiency and power was demonstrated. 5.5 W cw output obtained a slope of 52%. To the best our knowledge, this is highest reported for >5 Yb:YAG lasers.
In order to both experimentally and numerically investigate nonlinear femtosecond ultrabroadband-pulse propagation in a silica fiber, we have extended the finite-difference time-domain (FDTD) calculation of Maxwell's equations with terms that including all exact Sellmeier-fitting values. We compared results this FDTD method experimental results, as well solution generalized Schrodinger equation by split-step Fourier slowly varying-envelope approximation. To best our knowledge, is first...
Pulse duration dependence of ablation characteristics tetrafluoroethylene-hexafluoropropylene copolymer (FEP) film has been investigated with femtosecond and picosecond Ti:sapphire laser pulses at 798 nm. Laser fluence rates was examined for the pulse from 170 fs to 12 ps. Surface morphology ablated holes using a scanning electron microscope. A great difference found in durations around 170-fs longer than 500 fs. From analysis observation surface, we have that five-photon absorption...
An active chirp compensator consisting of a prism pair and spatial-phase-modulating pulse shaper enables us to accurately measure the third-order dispersion (TOD) dependence interferometric autocorrelation trace while keeping optimum group-delay constant. As result, it is shown that even small change in TOD (+60 fs3 -100 fs3) greatly affects temporal profile sub-8-fs region, 92-fs pulses at 75-MHz repetition rate from laser-oscillator glass-fiber system transform-limitedly compressed 7.1 fs.
Conventionally, the beam propagation method (BPM) for solving generalized nonlinear Schrödinger equation (GNLSE) including slowly varying envelope approximation (SVEA) has been used to describe ultrashort-laser-pulse in an optical fiber. However, if pulse duration approaches cycle regime (<10 fs), this becomes invalid. Consequently, it necessary use finite difference time domain (FDTD method) Maxwell with least approximation. In order both experimentally and numerically investigate...
Using a chirped pulse amplification technique, we have constructed Ti:sapphire regenerative amplifier with ring cavity. The amplified pulses an energy of 4 mJ were compressed to 120 fs at 797 nm and 170 746 nm. spectral distortion in the shapes investigated two different wavelengths.
Experimental results of nonlinear propagation with the induced-phase modulation (IPM) effect two-color 120 fs laser pulses three different initial delays in a silica fiber were analyzed finite-difference time domain (FDTD) calculations, including self-phase (SPM), IPM, and degenerate four-wave mixing (DFWM) fused-silica fiber. Initial delay dependence by FDTD qualitatively agrees previous experimental results. An ultrabroad spectrum induced IPM mostly that had optimum delay. A Fourier...
We demonstrated a 380 fs dual-wavelength independently mode-locked Yb:YAG ceramic laser at 1033.6 and 1047.6 nm. To the best of our knowledge, this is first mode locking achieved in Yb-doped solid-state lasers
The diode-end-pumped Yb:YAG ceramic tunable laser with the maximum output power of 6.8 W and slope efficiency 72% was demonstrated. range 118.3 nm from 992.5 to 1110.8 obtained.