scholarly journals High-resolution inversion for dispersion characteristics of acoustic logging waveforms

2020 ◽  
Vol 17 (3) ◽  
pp. 439-450
Author(s):  
Da Chen ◽  
Wei Guan ◽  
Chao Zhang ◽  
Qihang Zhou ◽  
Hengshan Hu
Keyword(s):  
Energy Spectrum ◽  
High Resolution ◽  
Extreme Point ◽  
Calculation Method ◽  
Single Mode ◽  
Dispersion Characteristics ◽  
Acoustic Logging ◽  
Multiple Modes ◽  
Logging While Drilling ◽  
Multi Mode

Abstract In acoustic logging, most published studies of extracting array data characteristics are difficult to avoid the interference from the false modes. The false modes contribute little to the acoustic waveforms but makes the true modes hard to identify. We introduce a threshold of the energy spectrum into the pole-calculation method to remove the false modes, thereby eliminating their interferences to the true modes. To avoid the separation of multiple crossings of pole distribution, we directly acquire the slowness dispersion of multiple modes by superposing the single-mode results calculated from the weighted spectral semblance method. We processed the slowness-frequency snapshot and design an extreme-point extraction formula to generate the multi-mode scatterplot, which provide a precise slowness dispersion result. In terms of four synthetic cases of acoustic logging, it has demonstrated that the proposed algorithm can provide a high-resolution slowness dispersion profile for multiple modes. Even for acoustic logging while drilling with strong tool wave components, the aliases and interferences of false modes do not exist. Finally, a test proves that the proposed algorithm also has a good anti-noise ability.

scholarly journals A Relaxation Filtering Approach for Two-Dimensional Rayleigh–Taylor Instability-Induced Flows

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 78 ◽  
Author(s):  
Sk. Mashfiqur Rahman ◽  
Omer San
Keyword(s):  
High Resolution ◽  
Numerical Experiments ◽  
Single Mode ◽  
Taylor Instability ◽  
Two Dimensional ◽  
Reconstruction Scheme ◽  
Rayleigh Taylor Instability ◽  
Multi Mode ◽  
Filtering Approach ◽  
Point Stencil

In this paper, we investigate the performance of a relaxation filtering approach for the Euler turbulence using a central seven-point stencil reconstruction scheme. High-resolution numerical experiments are performed for both multi-mode and single-mode

scholarly journals Peta-bit-per-second optical communications system using a standard cladding diameter 15-mode fiber

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Georg Rademacher ◽  
Benjamin J. Puttnam ◽  
Ruben S. Luís ◽  
Tobias A. Eriksson ◽  
Nicolas K. Fontaine ◽  
...  
Keyword(s):  
Wavelength Division Multiplexing ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Capacity Limits ◽  
Wavelength Division ◽  
Core Networks ◽  
Space Division Multiplexing ◽  
Space Division ◽  
Data Rates ◽  
Multi Mode

AbstractData rates in optical fiber networks have increased exponentially over the past decades and core-networks are expected to operate in the peta-bit-per-second regime by 2030. As current single-mode fiber-based transmission systems are reaching their capacity limits, space-division multiplexing has been investigated as a means to increase the per-fiber capacity. Of all space-division multiplexing fibers proposed to date, multi-mode fibers have the highest spatial channel density, as signals traveling in orthogonal fiber modes share the same fiber-core. By combining a high mode-count multi-mode fiber with wideband wavelength-division multiplexing, we report a peta-bit-per-second class transmission demonstration in multi-mode fibers. This was enabled by combining three key technologies: a wideband optical comb-based transmitter to generate highly spectral efficient 64-quadrature-amplitude modulated signals between 1528 nm and 1610 nm wavelength, a broadband mode-multiplexer, based on multi-plane light conversion, and a 15-mode multi-mode fiber with optimized transmission characteristics for wideband operation.

Dispersion properties of single-mode optical fibers in telecommunication region: poly (methyl methacrylate) (PMMA) versus silica

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hassan Pakarzadeh ◽  
Seyed Mostafa Rezaei ◽  
Mostafa Taghizadeh ◽  
Forough Bozorgzadeh
Keyword(s):  
Methyl Methacrylate ◽  
Optical Fibers ◽  
Spectral Range ◽  
Structural Parameters ◽  
Practical Importance ◽  
Single Mode ◽  
Dispersion Characteristics ◽  
Poly Methyl Methacrylate ◽  
Dispersion Wavelength ◽  
Zero Dispersion Wavelength

AbstractIn this paper, the dispersion characteristics of two standard single-mode optical fibers (SMFs), fabricated with silica and poly (methyl methacrylate) (PMMA) are studied in telecommunication spectral regions. The effect of structural parameters, such as the radius of the fiber core and the relative core-cladding index difference, is numerically investigated. It is found that over whole spectral range, the PMMA-based SMF shows lower dispersion than the silica SMF. Also, the zero-dispersion wavelength (ZDW) of PMMA-based SMF is longer than that of silica fiber. The results may be of practical importance for the telecommunication applications.

scholarly journals Optical whispering-gallery mode barcodes for high-precision and wide-range temperature measurements

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jie Liao ◽  
Lan Yang
Keyword(s):  
High Precision ◽  
Dynamic Range ◽  
Single Mode ◽  
Whispering Gallery Mode ◽  
Temperature Measurements ◽  
Laser Source ◽  
Multiple Modes ◽  
Whispering Gallery ◽  
Wide Range ◽  
Thermal Sensing

AbstractTemperature is one of the most fundamental physical properties to characterize various physical, chemical, and biological processes. Even a slight change in temperature could have an impact on the status or dynamics of a system. Thus, there is a great need for high-precision and large-dynamic-range temperature measurements. Conventional temperature sensors encounter difficulties in high-precision thermal sensing on the submicron scale. Recently, optical whispering-gallery mode (WGM) sensors have shown promise for many sensing applications, such as thermal sensing, magnetic detection, and biosensing. However, despite their superior sensitivity, the conventional sensing method for WGM resonators relies on tracking the changes in a single mode, which limits the dynamic range constrained by the laser source that has to be fine-tuned in a timely manner to follow the selected mode during the measurement. Moreover, we cannot derive the actual temperature from the spectrum directly but rather derive a relative temperature change. Here, we demonstrate an optical WGM barcode technique involving simultaneous monitoring of the patterns of multiple modes that can provide a direct temperature readout from the spectrum. The measurement relies on the patterns of multiple modes in the WGM spectrum instead of the changes of a particular mode. It can provide us with more information than the single-mode spectrum, such as the precise measurement of actual temperatures. Leveraging the high sensitivity of WGMs and eliminating the need to monitor particular modes, this work lays the foundation for developing a high-performance temperature sensor with not only superior sensitivity but also a broad dynamic range.

scholarly journals Silicon integrated multi-mode ring resonator

Nanophotonics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 1265-1272
Author(s):  
Mengyuan Ye ◽  
Chunlei Sun ◽  
Yu Yu ◽  
Yunhong Ding ◽  
Xinliang Zhang
Keyword(s):  
Integrated Circuit ◽  
Ring Resonator ◽  
Rapid Development ◽  
Essential Element ◽  
Single Mode ◽  
Modal Dispersion ◽  
Waveguide Width ◽  
Mode Division Multiplexing ◽  
Evanescent Coupling ◽  
Multi Mode

Abstract Ring resonator is an essential element in silicon integrated circuit, it is widely used as filter, wavelength multiplexer and switch in single-mode operation regime. As the rapid development of mode division multiplexing (MDM) technique, ring resonator that can process multi-mode signals simultaneously and uniformly is highly desired. However, the severe modal dispersion makes identical transmission for different modes very hard. In this paper, by breaking through the limitation of conventional multi-mode manipulation design with evanescent coupling or mode interference, we propose and demonstrate a multi-mode ring resonator (MMRR) inspired by the free space geometric optics. Arbitrary number of supporting modes can be achieved by simply widening the waveguide width. For proof-of-concept demonstration, an MMRR supporting four modes is fabricated with uniform transmittance. Furthermore, architecture of cascaded four MMRRs are also demonstrated experimentally.

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