arXiv subjects

Anna Suzuki

Publications and source records attributed to Anna Suzuki.

8 recordsLinked to original sources

arXiv2026

Scaling of broadband Ho:CALGO regenerative amplifier to multi-mJ pulse energy

We report on energy scaling of a 2.08-{\mu}m wavelength regenerative amplifier (RA) system based on the broadband gain material Ho:CaAlGdO4 (CALGO) to multi-mJ pulse energy at kHz repetition rates. Compared to previous reports, energy scaling was enabled thanks to an upgraded seed laser with a higher fluence and better spectral overlap to the gain spectrum of Ho:CALGO, which increased amplification efficiency. Bifurcation-free energy extraction was investigated experimentally and numerically for various repetition rates. A stable output was obtained at 10 W average power for repetition rates of 30 kHz and above. In addition, stable 3.4-mJ energy extraction was achieved at a 1-kHz repetition rate. We discuss the further scaling potential of pulse energy and pulse duration.

physics.optics↗

arXiv2026

Ho3+-doped CALGO crystals for high-power ultrafast 2.1-{\mu}m lasers

Ho3+-doped disordered CaAlGdO4 (CALGO) crystals have recently emerged as a promising gain material platform for next-generation high-power ultrafast 2.1-{\mu}m laser systems. This laser gain material offers a unique combination of high-gain, small quantum defect, inhomogeneously broadened spectra, and good thermal conductivity, enabling ultrashort pulse generation and amplification at high-average power and high pulse energy. Many systems, including mode-locked oscillators and amplifiers with state-of-the-art performance, have been demonstrated in the last few years that promise to meet growing application demands for efficient ultrafast laser technology in this wavelength region. In this review paper, we summarize recent achievements using this gain material both in oscillators and amplifiers and place these results in the state-of-the-art of 2-{\mu}m ultrafast laser technology, present detailed spectroscopic characterization of this material, and discuss future perspectives of further performance scaling of Ho:CALGO lasers.

physics.optics↗

arXiv2025

Energy scaling of Kerr-lens modelocked Ho:YAG thin-disk oscillators to the microjoule level

We demonstrate peak power and pulse energy scaling of Kerr-lens modelocking (KLM) Ho:YAG thin-disk lasers (TDLs) emitting at 2.1-{\mu}m wavelength. We compare different laser configurations to reach a maximum pulse energy of 1.7 {\mu}J at an output power of 29 W with a pulse duration of 434 fs, corresponding to a peak power of 3.7 MW. This represents a 5-fold increase in pulse energy and 4-fold increase in peak power compared to previous KLM Ho:YAG TDLs, thus reaching record high peak power for 2.1-{\mu}m mode-locked oscillators. We discuss current limitations at this wavelength and guidelines for future work towards higher power and pulse energies.

physics.optics↗

arXiv2024

High peak-power 2.1-{\mu}m femtosecond Holmium amplifier at 100 kHz

High-power ultrafast laser sources in the short-wave infrared region are of great interest for numerous applications, including secondary sources of radiation and processing of materials commonly opaque in the near-infrared region. In this wavelength region, direct laser amplification around 2.1-{\mu}m wavelength within the atmospheric transparency window is particularly attractive for realizing compact and efficient high-power lasers. However, this wavelength region was widely underrepresented in femtosecond laser technology so far. Here, we report on a 2.1-{\mu}m laser system delivering 97-fs pulses with an unprecedented combination of high peak power of 525 MW and high repetition rate of 100 kHz. The amplifier system consists of a mode-locked oscillator seeding a regenerative amplifier (RA) using the novel broadband material Holmium (Ho)-doped CaAlGdO4 (CALGO), operating in the chirped pulse amplification (CPA) scheme and a nonlinear compression stage based on a Herriott-type multi-pass cell (MPC) with bulk material. We demonstrate the potential of this unique laser system by generating a micro plasma in ambient air, demonstrating its high intensity for future plasma-driven secondary sources. This system bridges the gap between conventional 1-to-10 kHz amplifiers and high-power MHz laser oscillators in this attractive wavelength range.

physics.optics↗

arXiv2022

A Note on the "Various Atmospheres over Water Oceans on Terrestrial Planets with a One-Dimensional Radiative-Convective Equilibrium Model

It has been investigated the possibility of the various atmospheres over water oceans. We have considered the H$_2$ atmosphere and He atmosphere concerning to N$_2$ atmosphere over oceans. One of the main subjects in astrobiology is to estimate the habitable zone. If there is an ocean on the planet with an atmosphere, there is an upper limit to the outgoing infrared radiation called the Komabayashi-Ingersoll limit (KI-limit). This limit depends on the components of the atmospheres. We have investigated this dependence under the simple model, using the one-dimensional gray radiative-convective equilibrium model adopted by Nakajima et al. (1992). The outgoing infrared radiation ($F_{IRout}$) with the surface temperature ($T_s$) has shown some peculiar behavior. The examples for H$_2$, He, and N$_2$ background gas for H$_2$O vapour are investigated. There is another limit called the Simpson-Nakajima limit (SN-limit) mainly composed of vapour. This steam limit does not depend on the background atmosphere components. Under super-Earth case ($g=2\times$9.8 m/s$^2$), several cases are also calculated. The KI-limit dependence on the initial pressure is presented. The various emission rates by Koll & Cronin (2019) are investigated.

astro-ph.EP↗

arXiv2021

On the Possible Evolutionary History of the Water Ocean on Venus

We have investigated the possible evolutional history of the water ocean on Venus, adopting the one dimensional radiative-convective model,including the parameters as albedo and relative humidity. Under this model, it has the possibility that the habitable zone could include Venus. It could continue for $\sim 1$ Gy in faint young solar flux increasing, with modest parameters such as albedo = 0.3, relative humidity (RH=1), and $p_{n0}=10^5 $Pa. If we relax parameters considering the 3-Dimensional calculations, the ocean could exist there longer than $\sim$ 4.6 Gy. In such cases, we have to consider the cause of runaway other than just solar luminosity increasing. It is important to investigate Venus history for the coming future of Earth and observations of exoplanets for their historical habitable zones.

astro-ph.EP↗

arXiv2021

On the maximum principle for the multi-term fractional transport equation

In this paper, we prove a maximum principle for the general multi-term space-time-fractional transport equation and apply it for establishing uniqueness of solution to an initial-boundary-value problem for this equation. We also derive some comparison principles for solutions to the initial-boundary-value problems with different problem data. Finally, we present a maximum principle for the Cauchy problem for a time-fractional transport equation on an unbounded domain.

math.AP↗

arXiv2017

Constraints for the thawing and freezing potentials

We study the accelerating present universe in terms of the time evolution of the equation of state $w(z)$ (redshift $z$) due to thawing and freezing scalar potentials in the quintessence model. The values of $dw/da$ and $d^2w/da^2$ at scale factor of $a = 1$ are associated with two parameters of each potential. For five type scalar potentials, the scalar fields $Q$ and $w$ as function of time $t$ and/or $z$ are numerically calculated under the fixed boundary condition of $w(z=0)=-1+Δ$. The observational constraint $w_{obs}$ (Planck 2015) is imposed to test whether the numerical $w(z)$ is in $w_{obs}$. Some solutions show the thawing features in the freezing potentials. Mutually exclusive allowed regions in $dw/da$ vs. $d^2w/da^2$ diagram are obtained in order to identify the likely scalar potential and even the potential parameters by future observational tests.

astro-ph.CO↗