All-Optical In Situ Histology of Brain Tissue with Femtosecond Laser Pulses

Abstract All-optical magnetization reversal with femtosecond laser pulses facilitates the fastest and least dissipative magnetic recording, but writing magnetic bits with spatial resolution better than the wavelength of light has so far been seen as a major challenge. Here, we demonstrate that a single femtosecond laser pulse of wavelength 800 nm can be used to toggle the magnetization exclusively within one of two 10-nm thick magnetic nanolayers, separated by just 80 nm, without affecting the other one. The choice of the addressed layer is enabled by the excitation of a plasmon-polariton at a targeted interface of the nanostructure, and realized merely by rotating the polarization-axis of the linearly-polarized ultrashort optical pulse by 90°. Our results unveil a robust tool that can be deployed to reliably switch magnetization in targeted nanolayers of heterostructures, and paves the way to increasing the storage density of opto-magnetic recording by a factor of at least 2.

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Live cell bioimaging with carbon dots produced in situ by femtosecond laser from intracellular material

10.1101/455808 ◽

2018 ◽

Cited By ~ 1

Author(s):

Aleksander M. Shakhov ◽

Artyom A. Astafiev ◽

Alina A. Osychenko ◽

Maria S. Syrchina ◽

Viktor A. Nadtochenko

Keyword(s):

Femtosecond Laser ◽

Carbon Dots ◽

Near Infrared ◽

Laser Pulses ◽

Culture Cell ◽

Femtosecond Laser Pulses ◽

Live Cell ◽

Two Photon ◽

Two Photon Fluorescence

Owning to excellent optical properties and high biocompatibility carbon dots (CDs) have drawn increasing attention and have been widely applied as imaging agents for various bio-applications. Here we report a strategy for live-cell fluorescent bioimaging based on in situ synthesis of CDs within cells by tightly focused femtosecond laser pulses. Laser-produced carbon dots exhibit bright excitation-dependent fluorescence and are highly two-photon active under near infrared femtosecond excitation, thus demonstrating a potential for two-photon fluorescence imaging. The Raman spectra of fluorescent centers show strong D (1350 cm-1) and G (1590 cm-1) bands, thus suggesting that they are composed of carbon dots with sp2-hybridized core. Using Mouse GV oocytes as a model system we examine cytotoxicity and demonstrate the possibility of long-term fluorescent intracellular tracking of the laser-produced CDs. Created virtually in any point of the live cell, CD-based fluorescent μm-sized markers demonstrate high structural stability and retain bright fluorescence many hours after formation. Our results point to laser-produced fluorescent CDs as a highly-potent tool for cell cycle tracking, culture cell marking and probing intracellular movements.

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Magnetization Switching in the GdFeCo Films with In-Plane Anisotropy via Femtosecond Laser Pulses

Molecules ◽

10.3390/molecules26216406 ◽

2021 ◽

Vol 26 (21) ◽

pp. 6406

Author(s):

Daria O. Ignatyeva ◽

Pavel O. Kapralov ◽

Kiran Horabail Prabhakara ◽

Hiroki Yoshikawa ◽

Arata Tsukamoto ◽

...

Keyword(s):

Magnetic Field ◽

Femtosecond Laser ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Metal Alloys ◽

Magnetization Switching ◽

Small Magnetic Field ◽

Plane Anisotropy ◽

All Optical ◽

Out Of Plane

Ferrimagnetic rare-earth substituted metal alloys GdFeCo were shown to exhibit the phenomenon of all-optical magnetization switching via femtosecond laser pulses. All-optical magnetization switching has been comprehensively investigated in out-of-plane magnetized GdFeCo films; however, the films with the in-plane magnetic anisotropy have not yet been studied in detail. We report experimental observations of the magnetization switching of in-plane magnetized GdFeCo films by means of the femtosecond laser pulses in the presence of a small magnetic field of about 40 µT. The switching effect has a threshold both in the applied magnetic field and in the light intensity.

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