We report on a fiber-stabilized agile laser with ultra-low frequency noise. The frequency noise power spectral density is comparable to that of an ultra-stable cavity stabilized laser at Fourier frequencies higher than 30 Hz. When it is chirped at a constant rate of approximately 40 MHz/s, the max non-linearity frequency error is about 50 Hz peak-to-peak over more than 600 MHz tuning range. The Rayleigh backscattering is found to be a significant frequency noise source dependent on fiber length, chirping rate and the power imbalance of the interferometer arms. We analyze this effect both theoretically and experimentally and put forward techniques to reduce this noise contribution.
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http://dx.doi.org/10.1364/OE.18.003284 | DOI Listing |
Front Public Health
December 2024
Landscape Architecture College, Sichuan Agricultural University, Chengdu, China.
Introduction: The COVID-19 pandemic has underscored the health benefits of green spaces, yet research on how specific elements of natural infrastructure affect well-being during the pandemic has been limited.
Methods: This study, conducted at Sichuan Agricultural University with 300 students in 2022, investigated how urban natural infrastructure impacts physical and psychological well-being during the pandemic. Different aspects of natural infrastructure, such as thermal comfort, air quality (negative ion concentration), and noise and light levels, varied in their positive effects on students' health.
Toxicol Rep
December 2024
Department of Occupational Health and Ergonomic, Qazvin Medical University, Qazvin, Iran.
Occupational exposures are generally complex, workers are exposed with more than one hazardous agent in work environment. Combined exposure to noise and benzene is common in occupational environments. Sub-acute exposure to benzene vapors can induce oxidative stress in serum.
View Article and Find Full Text PDFJ Otol
July 2024
College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Chinese PLA Medical School, 28 Fuxing Road, Beijing, China.
Objective: This study aimed to develop and evaluate a novel software tool for robust analysis of the Visually Enhanced Vestibular-Ocular Reflex (VVOR) and video head impulse test (vHIT) saccades.
Methods: A retrospective study was conducted on 94 patients with Meniere's Disease (MD), unilateral vestibular hypofunction (UVH), and vestibular migraine (VM). The MATLAB-based VVOR Analysis System and Saccades All in One software were utilized for data processing.
Environ Pollut
December 2024
Department of Epidemiology and Health Statistics, School of Public Health, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, China; Key Laboratory of Environmental Factors and Chronic Disease Control, Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region 750004, China. Electronic address:
Current literature lacks information regarding impacts of green spaces on susceptibility to cardiovascular disease (CVD) related to harmful environmental exposures. The UK Biobank cohort study was utilized to investigate whether green spaces can mitigate risks associated with air pollutants, nighttime light, noise, and traffic intensity. Latent Profile Analysis was performed on green spaces and adverse environmental exposures in order to assess individual level exposure.
View Article and Find Full Text PDFSci Rep
December 2024
Xi'an Key Laboratory of Wellbore Integrity Evaluation, Xi'an Shiyou University, Xi'an, 710065, China.
Rolling bearings of the vibration exciter are prone to failure due to long-term high amplitude alternating impact loads, causing economic losses and threatening production safety. The heavy environmental noise during the operation of the vibration exciter and the high vibration level generated by the eccentric block make the weak bearing fault features submerged and difficult to extract. Teager-Kaiser energy operator is a popular method for extracting bearing fault features.
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