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1.
Phys Rev Lett ; 131(9): 096701, 2023 Sep 01.
Article in English | MEDLINE | ID: mdl-37721841

ABSTRACT

Finding efficient and ultrafast ways to control antiferromagnets is believed to be instrumental in unlocking their potential for magnetic devices operating at THz frequencies. Still, it is challenged by the absence of net magnetization in the ground state. Here, we show that the magnetization emerging from a state of coherent spin precession in antiferromagnetic iron borate FeBO_{3} can be used to enable the nonlinear coupling of light to another, otherwise weakly susceptible, mode of spin precession. This nonlinear mechanism can facilitate conceptually new ways of controlling antiferromagnetism.

2.
Rev Sci Instrum ; 94(7)2023 Jul 01.
Article in English | MEDLINE | ID: mdl-37498165

ABSTRACT

Usually, the presence of multiple eigenstates (magnons and phonons) in a system makes it difficult to analyze the coupled excitation mechanism using conventional single-pulse terahertz (THz) spectroscopy. On the contrary, 2D THz spectroscopy reveals energy flows between these states, which facilitates the identification of the coupled dynamics. In this article, we provide a theoretical description of this advanced technique and an experimental demonstration of its performance in antiferromagnet CoF2. Here, 2D THz spectroscopy shows that the THz pulse induces energy transfer from the magnon mode to the Raman-active phonon mode via a nonlinear excitation pathway.

3.
Opt Express ; 30(3): 3741-3748, 2022 Jan 31.
Article in English | MEDLINE | ID: mdl-35209626

ABSTRACT

We propose and experimentally prove efficient high-resolution electro-optic sampling measurement of broadband terahertz waveforms in a LiNbO3 crystal in the configuration with the probe laser beam propagating along the optical axis of the crystal. This configuration allows one to avoid the detrimental effect of strong intrinsic birefringence of LiNbO3 without any additional optical elements. To achieve velocity matching of the terahertz wave and the probe beam, the terahertz wave is introduced into the crystal through a Si prism at the Cherenkov angle to the probe beam. The workability of the scheme at different wavelengths of the probe optical beam (800 and 1550 nm) is demonstrated.

4.
Phys Rev Lett ; 127(3): 037203, 2021 Jul 16.
Article in English | MEDLINE | ID: mdl-34328781

ABSTRACT

THz magnetization dynamics of antiferromagnetically coupled spins in ferrimagnetic Tm_{3}Fe_{5}O_{12} is excited by a picosecond single-cycle pulse of a magnetic field and probed with the help of the magneto-optical Faraday effect. Data analysis combined with numerical modeling shows that the dynamics corresponds to the exchange mode excited by the Zeeman interaction of the THz magnetic field with the spins. We argue that THz-pump-IR-probe experiments on ferrimagnets offer a unique tool for quantitative studies of dynamics and mechanisms to control antiferromagnetically coupled spins.

5.
Phys Rev Lett ; 123(15): 157202, 2019 Oct 11.
Article in English | MEDLINE | ID: mdl-31702317

ABSTRACT

A nearly single cycle intense terahertz (THz) pulse with peak electric and magnetic fields of 0.5 MV/cm and 0.16 T, respectively, excites both modes of spin resonances in the weak antiferromagnet FeBO_{3}. The high frequency quasiantiferromagnetic mode is excited resonantly and its amplitude scales linearly with the strength of the THz magnetic field, whereas the low frequency quasiferromagnetic mode is excited via a nonlinear mechanism that scales quadratically with the strength of the THz electric field and can be regarded as a THz inverse Cotton-Mouton effect. THz optomagnetism is shown to be more energy efficient than similar effects reported previously for the near-infrared spectral range.

6.
Opt Express ; 26(18): 23359-23365, 2018 Sep 03.
Article in English | MEDLINE | ID: mdl-30184987

ABSTRACT

We report efficient high-resolution electro-optic sampling detection of broadband terahertz radiation by measuring direct intensity modulation of a femtosecond fiber laser beam induced by terahertz field in a 1-cm thick GaAs crystal.

7.
Opt Lett ; 39(24): 6779-82, 2014 Dec 15.
Article in English | MEDLINE | ID: mdl-25502995

ABSTRACT

We show that a Cherenkov emission of terahertz waves from a femtosecond optical pulse propagating in a LiNbO(3) crystal can be strongly spatially asymmetric with respect to the direction of the optical pulse propagation. We propose using this phenomenon to improve the spectral characteristics of one of the most efficient optical-to-terahertz converters: a thin LiNbO(3) layer attached to a Si-prism outcoupler.

8.
Opt Express ; 20(27): 28573-85, 2012 Dec 17.
Article in English | MEDLINE | ID: mdl-23263095

ABSTRACT

To circumvent a velocity mismatch between optical pump and terahertz waves in electro-optic crystals, we propose to use dual-wavelength optical beams tilted with respect to their planes of equal amplitude. The tilt is achieved by transmission of a dual-wavelength laser beam through a diffraction grating placed on the crystal boundary. The proposed technique extends optical rectification of tilted-front femtosecond laser pulses to difference-frequency generation with longer (nanosecond) pulses. Our analysis of the technique for LiNbO(3) pumped at 1.3 µm and GaAs pumped at 1.55 µm shows its efficiency.


Subject(s)
Lasers, Solid-State , Terahertz Radiation , Equipment Design , Equipment Failure Analysis
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