scholarly journals Light Amplification By Biofilm And Its Polarization Dependence

2017 ◽  
Author(s):  
Sanhita Ray ◽  
Anjan Kr Dasgupta
Keyword(s):  
Rayleigh Scattering ◽  
Scattered Light ◽  
Monochromatic Light ◽  
Pore Wall ◽  
Mie Scattering ◽  
Photonic Devices ◽  
Light Amplification ◽  
Enhancement Factors ◽  
Pore Wall Thickness

AbstractWe report amplified, transmitted light intensity, compared to input, when photosynthetic biofilms were placed in the path of Rayleigh scattered, monochromatic light. Enhancement spectrum shows peak at around 505 nm, which corresponds to the pore wall thickness in biofilm ultra-structure, suggesting role of resonant Mie scattering. Enhancement factors differed when biofilms from different stages of growth were used. Enhancement factors were found to depend on the nature of Rayleigh scattering liquid. Polarizing Rayleigh scattered light by the use of polarizers affected the percentage of enhancement. Amplified output is achievable with constructive interference arising out of coherent forward light scattering, a theoretically predicted outcome of Anderson localization of photons. Possible uses of photosynthetic biofilms in organic material based photonic devices have been discussed.

Atmospheric Scattering

2017 ◽  
Author(s):  
Kelly Chance ◽  
Randall V. Martin
Keyword(s):  
Function Approximation ◽  
Legendre Polynomials ◽  
Rayleigh Scattering ◽  
Scattered Light ◽  
Incident Light ◽  
Mie Scattering ◽  
Spherical Particles ◽  
Atmospheric Scattering ◽  
Phase Functions ◽  
Scatterer Size

This chapter describes elastic scattering events, where the wavelength of the scattered light is unchanged from that of the incident light and conservative scattering, scattering without absorption, sometimes closely approximated in clouds. The scattering regime, scattering versus wavelengths and scatterer size are introduced. Polarization in scattering is described by the Stokes vector and the polarization ellipse. Molecular (Rayleigh) scattering is presented and its atmospherically-important inelastic component, Raman scattering (the Ring effect) quantified. Mie scattering for spherical particles is described as is the commonly-used Henyey-Greenstein Mie phase function approximation. Non-spherical scatterers are introduced. The Ångstrom exponent and the expansion of phase functions in Legendre polynomials are described.

scholarly journals Surface-Enhanced Raman Scattering: Introduction and Applications

2020 ◽  
Author(s):  
Samir Kumar ◽  
Prabhat Kumar ◽  
Anamika Das ◽  
Chandra Shakher Pathak
Keyword(s):  
Raman Spectroscopy ◽  
Raman Scattering ◽  
Rayleigh Scattering ◽  
Scattered Light ◽  
Monochromatic Light ◽  
Surface Enhanced Raman Scattering ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Laser Sources

Scattering of light by molecules can be elastic, Rayleigh scattering, or inelastic, Raman scattering. In the elastic scattering, the photon’s energy and the state of the molecule after the scattering events are unchanged. Hence, Rayleigh scattered light does not contain much information on the structure of molecular states. In inelastic scattering, the frequency of monochromatic light changes upon interaction with the vibrational states, or modes, of a molecule. With the advancement in the laser sources, better and compact spectrometers, detectors, and optics Raman spectroscopy have developed as a highly sensitive technique to probe structural details of a complex molecular structure. However, the low scattering cross section (10−31) of Raman scattering has limited the applications of the conventional Raman spectroscopy. With the discovery of surface-enhanced Raman scattering (SERS) in 1973 by Martin Fleischmann, the interest of the research community in Raman spectroscopy as an analytical method has been revived. This chapter aims to familiarize the readers with the basics of Raman scattering phenomenon and SERS. This chapter will also discuss the latest developments in the SERS and its applications in various fields.

Aeolus Rayleigh-channel winds in cloudy conditions

2021 ◽  
Author(s):  
Gert-Jan Marseille
Keyword(s):  
Rayleigh Scattering ◽  
Scattered Light ◽  
Weather Prediction ◽  
Ultra Violet ◽  
Mie Scattering ◽  
Atmospheric Conditions ◽  
Atmospheric Flow ◽  
Rayleigh Channel ◽  
Wind Profiles ◽  
Height Assignment

<p>Aeolus was launched in August 2018 and is expected to be operational until 2022. Aeolus is the first Doppler wind lidar in space to measure wind profiles through Rayleigh scattering of an ultra-violet laser beam and the determination of the Doppler shift of the scattered light by molecules along the Line-Of-Sight (LOS). In addition, Mie scattering provides winds on aerosol and cloud particles. The atmosphere return signal is a small bandwidth peak (from Mie scattering) on top of a broadband spectrum (from Rayleigh scattering). The tails and central part of the spectrum are being processed separately to yield so-called Rayleigh channel and Mie channel winds respectively.</p><p>Signals in both channels are being accumulated onboard the satellite to segments of 2.85 km length along the satellite track, denoted measurements. Rayleigh winds are obtained by on-ground processing through accumulating typically 30 measurements to yield a single Rayleigh wind observation of sufficient quality for use in Numerical Weather Prediction (NWP). The vertical resolution of the horizontally projected LOS wind profiles is typically 500 m in the boundary layer, 1 km in the free-troposphere and 1.5-2 km in the stratosphere, but this can and has been changed in a flexible way during the mission.</p><p>In case of clouds and/or aerosols presence within the sensing atmospheric volume, signal from Mie scattering leaks into the Rayleigh channel signal. Since the Rayleigh-channel signal processing assumes a pure molecular signal this so-called Mie contamination causes biases in retrieved winds. This is solved through classifying measurements as either ‘clear’ or ‘cloudy’ before accumulation to observation level. Clear measurements (out of a total of 30) are accumulated to yield a Rayleigh-clear wind. This procedure has proven successful and Aeolus Rayleigh-clear winds are used operationally today by a number of meteorological centers around the world.</p><p>A similar procedure for cloudy measurements is less trivial and requires correction for Mie contamination. So far, implemented corrections were not successful in producing Rayleigh-cloudy winds of sufficient quality for use in NWP. A new correction scheme has been introduced and tested recently and proved successful to produce bias-free winds and a random error slightly larger as compared to Rayleigh-clear winds. The latter is explained by increased heterogeneous atmospheric conditions in which Rayleigh-cloudy winds are obtained. Interestingly, Rayleigh-cloudy and Mie-cloudy winds are obtained for identical atmospheric conditions and as such provide independent information on the atmospheric flow, which allows to characterize the error sources of the different types of wind observations, including instrumental/calibration errors, but also errors due to incorrect height assignment and representativity.</p><p>This paper describes the new scheme to correct Rayleigh winds for Mie contamination and its application to Aeolus data. The results show that resulting Rayleigh-cloudy winds are of good quality to be considered for operational use in NWP.</p>

scholarly journals A Review on Metamaterials for Device Applications

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 518
Author(s):  
N. Suresh Kumar ◽  
K. Chandra Babu Naidu ◽  
Prasun Banerjee ◽  
T. Anil Babu ◽  
B. Venkata Shiva Reddy
Keyword(s):  
Quantum Interference ◽  
Effective Properties ◽  
Photonic Devices ◽  
Vital Role ◽  
Major Type ◽  
Electric Permittivity ◽  
Superconducting Quantum Interference Devices ◽  
Device Applications ◽  
Microwave Sensors

Metamaterials are the major type of artificially engineered materials which exhibit naturally unobtainable properties according to how their microarchitectures are engineered. Owing to their unique and controllable effective properties, including electric permittivity and magnetic permeability, the metamaterials play a vital role in the development of meta-devices. Therefore, the recent research has mainly focused on shifting towards achieving tunable, switchable, nonlinear, and sensing functionalities. In this review, we summarize the recent progress in terahertz, microwave electromagnetic, and photonic metamaterials, and their applications. The review also encompasses the role of metamaterials in the advancement of microwave sensors, photonic devices, antennas, energy harvesting, and superconducting quantum interference devices (SQUIDs).

scholarly journals Detection of Fire Smoke Plumes Based on Aerosol Scattering Using VIIRS Data over Global Fire-Prone Regions

2021 ◽  
Vol 13 (2) ◽  
pp. 196
Author(s):  
Xiaoman Lu ◽  
Xiaoyang Zhang ◽  
Fangjun Li ◽  
Mark A. Cochrane ◽  
Pubu Ciren
Keyword(s):  
Infrared Imaging ◽  
Scattered Light ◽  
Detection Algorithm ◽  
Mie Scattering ◽  
Spectral Contrast ◽  
Aerosol Scattering ◽  
Smoke Plumes ◽  
Fire Smoke ◽  
Weather And Human Health ◽  
Aerosol Index

Smoke from fires significantly influences climate, weather, and human health. Fire smoke is traditionally detected using an aerosol index calculated from spectral contrast changes. However, such methods usually miss thin smoke plumes. It also remains challenging to accurately separate smoke plumes from dust, clouds, and bright surfaces. To improve smoke plume detections, this paper presents a new scattering-based smoke detection algorithm (SSDA) depending mainly on visible and infrared imaging radiometer suite (VIIRS) blue and green bands. The SSDA is established based on the theory of Mie scattering that occurs when the diameter of an atmospheric particulate is similar to the wavelength of the scattered light. Thus, smoke commonly causes Mie scattering in VIIRS blue and green bands because of the close correspondence between smoke particulate diameters and the blue/green band wavelengths. For developing the SSDA, training samples were selected from global fire-prone regions in North America, South America, Africa, Indonesia, Siberia, and Australia. The SSDA performance was evaluated against the VIIRS aerosol detection product and smoke detections from the ultraviolet aerosol index using manually labeled fire smoke plumes as a benchmark. Results show that the SSDA smoke detections are superior to existing products due chiefly to the improved ability of the algorithm to detect thin smoke and separate fire smoke from other surface types. Moreover, the SSDA smoke distribution pattern exhibits a high spatial correlation with the global fire density map, suggesting that SSDA is capable of detecting smoke plumes of fires in near real-time across the globe.

scholarly journals Role of Mie scattering in the seeding of matter-wave superradiance

2012 ◽  
Vol 86 (4) ◽  
Author(s):  
R. Bachelard ◽  
H. Bender ◽  
Ph. W. Courteille ◽  
N. Piovella ◽  
C. Stehle ◽  
...  
Keyword(s):  
Mie Scattering ◽  
Matter Wave

scholarly journals Strain-rate enhancement at Dye 3, Greenland

1999 ◽  
Vol 45 (150) ◽  
pp. 338-345 ◽  
Author(s):  
Throstur Thorsteinsson ◽  
E. D. Waddington ◽  
K. C. Taylor ◽  
R. B. Alley ◽  
D. D. Blankenship
Keyword(s):  
Crystal Size ◽  
Ice Sheets ◽  
Ion Concentration ◽  
Strain Rates ◽  
Anisotropic Flow ◽  
Enhancement Factors ◽  
Measured Strain ◽  
Soluble Ion ◽  
Flow Laws

AbstractIce at depth in ice sheets can be softer in bed-parallel shear than Glen’s flow law predicts. For example, at Dye 3, Greenland, enhancement factors of 3 4 are needed in order to explain the rate of borehole tilting Previous authors have identified crystal fabric as the dominant contributor, but the role of impurities and crystal size is still incompletely resolved. Here we use two formulations of anisotropic flow laws for ice (Azuma’s and Sachs’ models) to account for the effects of anisotropy, and show that the measured anisotropy of the ice at Dye 3 cannot explain all the detailed variations in the measured strain rates, the jump in enhancement across the Holocene–Wisconsin boundary is larger than expected from the measured fabrics alone. Dust and soluble-ion concentration divided by crystal size correlates well with the residual enhancement, indicating that most of the “excess deformation” may be due to impurities or crystal size. While the major features of the deformation at Dye 3 are explained by anisotropy and temperature, results also suggest that further research into the role of impurities and crystal size is warranted.

The Polarization Properties Research of Atmospheric Based on Actual Weather Conditions

2014 ◽  
Vol 556-562 ◽  
pp. 933-936
Author(s):  
Fei Zhang ◽  
Xiao Ping Du ◽  
Shen Wang
Keyword(s):  
Rayleigh Scattering ◽  
Weather Conditions ◽  
Mie Scattering ◽  
New Method ◽  
Degree Of Polarization ◽  
Scattering Angle ◽  
Polarization Characteristics ◽  
Simulation Results

A new method to calculate the polarization properties of the atmosphere by combining the Rayleigh scattering and Mie scattering is proposed in this paper. We inversed the values of the required data by experiment and simulated of the atmosphere polarization characteristics under the same conditions. The simulation results show that the proposed method can accurately describe the variation of the atmosphere polarization properties. Besides, the results show such variation: in the same weather conditions, the degree of polarization is gradually increased while scattering angle is gradually increased as 90°; in the same detect conditions, the degree of polarization decreases with the deteriorating weather conditions.

Design and Compiling of Laser Propagation Simulation Software in Atmospheric Environment

2012 ◽  
Vol 490-495 ◽  
pp. 2136-2140
Author(s):  
Tong Gang Zhao ◽  
Zhi Qiang Zhang
Keyword(s):  
Theoretical Model ◽  
Rayleigh Scattering ◽  
Hot Spot ◽  
Theoretical Models ◽  
Mie Scattering ◽  
Simulation System ◽  
Simulation Software ◽  
Atmospheric Environment ◽  
Laser Propagation ◽  
Atmospheric Propagation

As development of laser technology, the characteristic of laser atmospheric propagation is always hot spot in laser domain. Using theoretical models of laser atmospheric propagation, a simulation system is researched by implementing a scientific method of software development. This simulation system can simulate the radiate property of laser propagation in atmosphere, and demonstrate the course of laser propagation. This theoretical model of atmospheric propagation is based on Lambert-Beer law, combined with other classic theoretical model such as Rayleigh scattering and Mie scattering. Multiple scattering theories are used when simulating the laser propagation in smoke or fog. In calculation, the atmosphere is divided into layer. An appropriate model will be selected for calculation in each layer in order to enhance the stimulation precision. Lastly, the figure of light spot is drawn along with transmission space. Laser atmospheric propagation is demonstrated.

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