A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavity. The main ring cavity provides forward stimulated Brillouin scattering gain and utilizes a nonlinear polarization rotation effect to achieve TR mode locking. By combining the sub ring cavity with the main ring cavity and utilizing the Vernier effect, the TR mode microwave photonic single longitudinal mode (SLM) output can be ensured. Meanwhile, the 6.281 Hz narrow linewidth of the TR mode is achieved by reducing the intrinsic linewidth of the passive resonant cavity. The acoustic mode suppression ratio and side mode suppression ratio of the TR mode were 43 dB and 54 dB, respectively. The power and frequency fluctuations of within 40 min were approximately ±0.49 dB and ±0.187 kHz, indicating good stability. At a frequency offset of 10 kHz, the TR mode had a low phase noise value of -110 dBc/Hz. This solution can be used in various fields, such as high-precision radar detection, long-distance optical communication, and high-performance fiber optic sensing.
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http://dx.doi.org/10.3390/mi16010097 | DOI Listing |
Micromachines (Basel)
January 2025
Key Laboratory of Instrumentation Science and Dynamic Measurement Ministry of Education, North University of China, Taiyuan 030051, China.
A Hz level narrow linewidth all-optical microwave oscillator based on the torsional radial acoustic modes (TR) of a single-mode fiber (SMF) is proposed and validated. The all-optical microwave oscillator consists of a 20 km SMF main ring cavity and a 5 km SMF sub ring cavity. The main ring cavity provides forward stimulated Brillouin scattering gain and utilizes a nonlinear polarization rotation effect to achieve TR mode locking.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States.
We present direct frequency comb cavity ring-down spectroscopy with Vernier filtering as a straightforward approach to sensitive and multiplexed trace gas detection. The high finesse cavity acts both to extend the interaction length with the sample and as a spectral filter, alleviating the need for dispersive elements or an interferometer. In this demonstration, a free running interband cascade laser was used to generate a comb centered at 3.
View Article and Find Full Text PDFHeliyon
January 2025
Department of Mathematics, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, 8100, Bangladesh.
The numerical analysis examines the attributes of magnetohydrodynamic natural convection in a closed cavity including a circular hollow. Because mono and hybrid nanofluids have many applications in thermal engineering and manufacturing, hybrid nanofluids are utilized as the substance within the entire domain. The investigation centers on a closed, trapezoidal-shaped hollow with a heated surface ring.
View Article and Find Full Text PDFACS Earth Space Chem
January 2025
Earth and Environmental Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States.
Naturally occurring bedded salt deposits are considered robust for the permanent disposal of heat-generating nuclear waste due to their unique physical and geological properties. The Brine Availability Test in Salt (BATS) is a US-DOE Office of Nuclear Energy funded project that uses heated borehole experiments underground (∼655 meters depth) at the Waste Isolation Pilot Plant (WIPP) in the bedded salt deposits of the Salado Formation to investigate the capacity for safe disposal of high-level, heat generating nuclear waste in salt. Uncertainties associated with brine mobility near heat-generating waste motivates the need to characterize the processes and sources of brine in salt deposits.
View Article and Find Full Text PDFAm J Ophthalmol
January 2025
Raghudeep Eye Hospital, Laden Cataract and IOL research centre, Ahmedabad, India 380052.
Purpose: To evaluate demographic profile, risk factors and outcomes following intraocular lens (IOL) exchange surgery for late decentration of IOLs in the dead bag syndrome DESIGN: Prospective, interventional case series PARTICIPANTS: 46 eyes (43 patients) with late decentration/dislocation of IOLs and spontaneous posterior capsule rupture in a clear and relatively intact capsular bag. None of the eyes had significant zonular weakness.
Methods: Study conducted at Raghudeep Eye Hospital, India.
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