We demonstrate propagation of 14 nJ femtosecond pulses through a large-mode-area, higher-order-mode (HOM) fiber with an effective area of 2100 microm2. The pulses propagate stably in the LP07 mode of the fiber through lengths as long as 12 m. The strongly chirped pulses exiting the amplifier fiber are dechirped by the high-order-mode fiber, resulting in pulses with a peak power of 61 kW after propagation in 5 m of the positive-dispersion fiber. A small amount of self-phase modulation is observed in the compressed pulses and is described well by a nonlinear Schrödinger equation model that takes into account the measured effective area and dispersion of the HOM fiber.
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http://dx.doi.org/10.1364/ol.31.003191 | DOI Listing |
ACS Omega
January 2025
Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
The spatial propagation of neuronal activity within neuronal circuits, which is associated with brain functions, such as memory and learning, is regulated by external stimuli. Conventional external stimuli, such as electrical inputs, pharmacological treatments, and optogenetic modifications, have been used to modify neuronal activity. However, these methods are tissue invasive, have insufficient spatial resolution, and cause irreversible gene modifications.
View Article and Find Full Text PDFSmall
January 2025
Faculty of Physics and Astronomy, Adam Mickiewicz University, Poznan, 61-614, Poland.
The behavior of triple-cation mixed halide perovskite solar cells (PSCs) under ultrashort laser pulse irradiation at varying fluences is investigated, with a focus on local heating effects observed in femtosecond transient absorption (TA) studies. The carrier cooling time constant is found to increase from 230 fs at 2 µJ cm⁻ to 1.3 ps at 2 mJ cm⁻ while the charge population decay accelerates from tens of nanoseconds to the picosecond range within the same fluence range.
View Article and Find Full Text PDFNat Nanotechnol
January 2025
Department of Chemistry, Columbia University, New York, NY, USA.
Van der Waals (vdW) semiconductors have emerged as promising platforms for efficient nonlinear optical conversion, including harmonic and entangled photon generation. Although major efforts are devoted to integrating vdW materials in nanoscale waveguides for miniaturization, the realization of efficient, phase-matched conversion in these platforms remains challenging. Here, to address this challenge, we report a far-field ultrafast imaging method to track the propagation of both fundamental and harmonic waves within vdW waveguides with femtosecond and sub-50 nanometre spatiotemporal precision.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada.
We report a nonlinear terahertz (THz) detection device based on a metallic bull's-eye plasmonic antenna. The antenna, fabricated with femtosecond laser direct writing and deposited on a nonlinear gallium phosphide (GaP) crystal, focuses incoming THz waveforms within the sub-wavelength bull's eye region to locally enhance the THz field. Additionally, the plasmonic structure minimizes diffraction effects allowing a relatively long interaction length between the transmitted THz field and the co-propagating near-infrared gating pulse used in an electro-optic sampling configuration.
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