Causality and special relativity pose an upper limit to the amount of advance that an optical pulse can acquire during a superluminal propagation. Such a limit can be circumvented if the pulse, before entering the superluminal medium, is retarded by letting it propagate under normal dispersion. We present an experimental evidence of this fact by showing that a laser pulse propagating in an atomic vapor, quasi resonant with an inverted transition and in conditions of anomalous dispersion, moves faster if it is previously retarded in a cell containing the same medium with no population inversion. Optical transmission lines often need an amplification stage to overcome the signal attenuation and the unavoidable delay respect to propagation at c; in this paper we tailor such stage to provide also an optical controlled recover of such delay. We believe that our results can open exciting prospects for real-life optical data processing and communication.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OE.22.028566 | DOI Listing |
Cornea
January 2025
Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil.
Purpose: To evaluate the efficacy and safety of intense pulsed light (IPL) combined with meibomian gland expression (MGX) for the treatment of dry eye disease and meibomian gland dysfunction associated with chronic Stevens-Johnson syndrome and toxic epidermal necrolysis.
Methods: This prospective noncomparative interventional study included 29 patients (58 eyes) who underwent 3 sessions of IPL and MGX at 2-week intervals. Subjective symptoms (ocular surface disease index score) and objective dry eye tests: matrix metalloproteinase 9, tear meniscus height, bulbar redness score, tear film lipid layer thickness (LLT), Schirmer I test, conjunctival and corneal staining, meibomian gland loss, MGX score [meibomian gland score (MGS)], and tear break-up time were assessed at the baseline and after 4, 8, and 12 weeks.
Phys Chem Chem Phys
January 2025
Theoretical Physics Section, Bhabha Atomic Research Centre, Mumbai-400085, India.
Extensive research on ultrashort laser-induced melting of noble metals like Au, Ag and Cu is available. However, studies on laser energy deposition and thermal damage of their alloys, which are currently attracting interest for energy harvesting and storage devices, are limited. This study investigates the melting damage threshold (DT) of three intermetallic alloys of Au and Cu (AuCu, AuCu and AuCu) subjected to single-pulse femtosecond laser irradiation, comparing them with their constituent metals.
View Article and Find Full Text PDFAdv Sci (Weinh)
January 2025
ENT Institute and Department of Otolaryngology, Eye & ENT Hospital of Fudan University, Shanghai, 200031, China.
Tinnitus, a widespread condition affecting numerous individuals worldwide, remains a significant challenge due to limited effective therapeutic interventions. Intriguingly, patients using cochlear implants (CIs) have reported significant relief from tinnitus symptoms, although the underlying mechanisms remain unclear and intracochlear implantation risks cochlear damage and hearing loss. This study demonstrates that targeted intracochlear electrical stimulation (ES) in guinea pigs with noise-induced hearing loss reversed tinnitus-related maladaptive plasticity in the cochlear nucleus (CN), characterized by reduced auditory innervation, increased somatosensory innervation, and diminished inhibitory neural networks.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Chemistry, Brandeis University, 415 South Street, Waltham, Massachusetts 02453, United States.
The photocatalytic efficiency of materials such as graphene and noble metal nanoclusters depends on their plasmon lifetimes. Plasmon dephasing and decay in these materials is thought to occur on ultrafast time scales, ranging from a few femtoseconds to hundreds of femtoseconds and longer. Here we focus on understanding the dephasing and decay pathways of excited states in small lithium and silver clusters and in plasmonic states of the π-conjugated molecule anthracene, providing insights that are crucial for interpreting optical properties and photophysics.
View Article and Find Full Text PDFAdv Mater
January 2025
Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149, Münster, Germany.
As a phase change material (PCM), antimony exhibits a set of desirable properties that make it an interesting candidate for photonic memory applications. These include a large optical contrast between crystalline and amorphous solid states over a wide wavelength range. Switching between the states is possible on nanosecond timescales by applying short heating pulses.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!
© LitMetric 2025. All rights reserved.