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Graphene and thin graphite films for ultrafast optical Kerr gating at 1 GHz repetition rate under focused illumination
Amr Farrag, Assegid M. Flatae, Mario Agio
https://arxiv.org/abs/2511.17713 https://arxiv.org/pdf/2511.17713 https://arxiv.org/html/2511.17713
arXiv:2511.17713v1 Announce Type: new
Abstract: The ability to address sub-picosecond events of weak optical signals is essential for progress in quantum science, nonlinear optics, and ultrafast spectroscopy. While up-conversion and optical Kerr gating (OKG) offer femtosecond resolution, they are generally limited to ensemble measurements, making ultrafast detection in nano-optics challenging. OKG, with its broadband response and high throughput without phase-matching, is especially promising when used at high repetition rates under focused illumination.
Here, we demonstrate an ultrafast detection scheme using the third-order nonlinearity of graphene and thin graphite films, operating at 1 GHz with sub-nanojoule pulses and achieving 141 fs temporal resolution. Their exceptionally large nonlinear refractive index, orders of magnitude higher than conventional Kerr media, enhances detection efficiency at smaller thicknesses, enables sub-picosecond response, and supports broadband operation. Their atomic-scale thickness minimizes dispersion and simplifies integration with microscopy platforms, optical fibers, and nanophotonic circuits, making them a compact, practical material platform for nano-optical and on-chip ultrafast Kerr gating.
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Gas stoves are filling millions of homes with hidden toxic air #environment

Gas stoves are filling millions of homes with hidden toxic air
Stanford researchers found that gas stoves expose Americans to surprisingly high levels of nitrogen dioxide—often matching or exceeding outdoor pollution. For millions, cooking alone pushes NO2 over long-term safety thresholds. Smaller homes, renters, and rural households face the highest concentrations. Cleaner cooking technologies could substantially reduce the risks.