We demonstrate all fiber Fabry-Perot resonators (F-P resonators) based on Sagnac loop mirrors assembled with tellurite microfibers. As-assembled F-P resonators, with dimensions of hundreds of micrometers, show clear resonant responses with typical quality factor of about 5700, free spectral range of about 1 nm, and a maximum extinction ratio of 18 dB. The reflectivity of the loop mirror and the effective cavity length of the F-P resonator can be tuned by micromanipulation under an optical microscope. F-P resonators demonstrated here show advantages of small size, good resonance, easy fabrication, tunability, and easy integration with fiber systems.
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http://dx.doi.org/10.1364/ol.34.000253 | DOI Listing |
Anal Chem
January 2025
School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian 116024, Liaoning, China.
A cantilever-enhanced fiber-optic photoacoustic (PA) spectrophone is reported for trace gas detection at a low-pressure environment. A cantilever-based fiber-optic Fabry-Perot (F-P) interferometer (FPI) is utilized for simultaneous measurement of air pressure and PA pressure. Since the cantilever resonance frequency follows air pressure linearly, the fundamental frequency intensity modulation (1-IM) technique is applied to scan the frequency response of the solid PA signal from tube wall absorption for tracking the cantilever resonance frequency in real time.
View Article and Find Full Text PDFHum Brain Mapp
January 2025
Queen Square Multiple Sclerosis Centre, Department of Neuroinflammation, UCL Queen Square Institute of Neurology, University College London, London, UK.
Disruptions to brain networks, measured using structural (sMRI), diffusion (dMRI), or functional (fMRI) MRI, have been shown in people with multiple sclerosis (PwMS), highlighting the relevance of regions in the core of the connectome but yielding mixed results depending on the studied connectivity domain. Using a multilayer network approach, we integrated these three modalities to portray an enriched representation of the brain's core-periphery organization and explore its alterations in PwMS. In this retrospective cross-sectional study, we selected PwMS and healthy controls with complete multimodal brain MRI acquisitions from 13 European centers within the MAGNIMS network.
View Article and Find Full Text PDFHum Brain Mapp
December 2024
Department of Psychiatry and Psychotherapy, University Hospital LMU, Munich, Germany.
Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique used to modulates cortical brain activity. However, its effects on brain metabolites within the dorsolateral prefrontal cortex (DLPFC), a crucial area targeted for brain stimulation in mental disorders, remain unclear. This study aimed to investigate whether prefrontal tDCS over the left and right DLPFC modulates levels of key metabolites, including gamma-aminobutyric acid (GABA), glutamate (Glu), glutamine/glutamate (Glx), N-acetylaspartate (NAA), near to the target region and to explore potential sex-specific effects on these metabolite concentrations.
View Article and Find Full Text PDFSci Rep
December 2024
Experimental and Clinical Research Center, a Cooperation Between Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Charité - Universitätsmedizin Berlin, Geschäftsführung, Charitéplatz 1, 10117, Berlin, Germany.
Quantitative magnetic resonance imaging (qMRI) involves mapping microstructure in standardized units sensitive to histological properties and supplements conventional MRI, which relies on contrast weighted images where intensities have no biophysical meaning. While measuring tissue properties such as myelin, iron or water content is desired in a disease context, qMRI changes may typically reflect mixed influences from aging or pre-clinical degeneration. We used a fast multi-parameter mapping (MPM) protocol for clinical routine at 3T to reconstruct whole-brain quantitative maps of magnetization transfer saturation (MT), proton density (PD), longitudinal (R1), and transverse relaxation rate (R2*) with 1.
View Article and Find Full Text PDFNanophotonics
April 2024
The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin 300071, People's Republic of China.
The linear electro-optic effect offers a valuable means to control light properties via an external electric field. Lithium niobate (LN), with its high electro-optic coefficients and broad optical transparency ranges, stands out as a prominent material for efficient electro-optic modulators. The recent advent of lithium niobate-on-insulator (LNOI) wafers has sparked renewed interest in LN for compact photonic devices.
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