We show that the temporal broadening of a pulsed, tightly focused TEM(00) beam propagating in a scattering medium can be accurately modeled as a convolution between the initial pulse profile and an effective impulse response that is given by the propagation behavior of an infinitely thin pulse in the said medium. The impulse response is obtained with a Monte Carlo (MC) analysis of the propagating photons in the impulse. Our algorithm is 2 orders of magnitude less complex than the full MC solution of the pulse propagation problem. The accuracies, however, are comparable even for scattering path lengths that are 20 times the mean free path.
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http://dx.doi.org/10.1364/ao.38.005433 | DOI Listing |
Ultrashort pulse sources are complex and resource-intensive. To reduce overhead and simplify operations, we had previously developed a method to deliver ultra-short pulses through fiber-optic links to multiple locations and to characterize them remotely using a compact detector module. We created a pulse pair with varying delays at the central location using a pulse shaper before launching them into the fiber links and measured the first and second-order autocorrelations at the satellite location.
View Article and Find Full Text PDFA 2.6-fold spectral broadening of mid-infrared femtosecond µJ-level pulses has been achieved using an unfolded multi-pass configuration of germanium plates and zinc selenide lenses. This method maintains a throughput higher than 60% while preserving the spatial quality and the temporal duration of the input beam.
View Article and Find Full Text PDFHigh-order solitons exhibit fascinating dynamics during their propagation in anomalous dispersion media. High-order soliton dynamics have been intensively exploited for extreme pulse compression and coherent ultra-broadband spectrum generation. Despite recent advances, most previous studies have been restricted to soliton propagation external to a laser cavity, leaving the intracavity generation and evolution of high-order solitons less explored.
View Article and Find Full Text PDFSensors (Basel)
January 2025
Department of Biomedical Engineering, Price Faculty of Engineering, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.
Goal: Current methodologies for assessing cerebral compliance using pressure sensor technologies are prone to errors and issues with inter- and intra-observer consistency. RAP, a metric for measuring intracranial compensatory reserve (and therefore compliance), holds promise. It is derived using the moving correlation between intracranial pressure (ICP) and the pulse amplitude of ICP (AMP).
View Article and Find Full Text PDFElife
January 2025
Department of Neurobiology, Harvard Medical School, Boston, United States.
Unipolar brush cells (UBCs) are excitatory interneurons in the cerebellar cortex that receive mossy fiber (MF) inputs and excite granule cells. The UBC population responds to brief burst activation of MFs with a continuum of temporal transformations, but it is not known how UBCs transform the diverse range of MF input patterns that occur in vivo. Here, we use cell-attached recordings from UBCs in acute cerebellar slices to examine responses to MF firing patterns that are based on in vivo recordings.
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