scholarly journals Glass-on-Glass Fabrication of Bottle-Shaped Tunable Microlasers and their Applications

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Jonathan M. Ward ◽  
Yong Yang ◽  
Síle Nic Chormaic
Keyword(s):  
Gas Flow ◽  
60 Ghz ◽  
Melting Points ◽  
Simple Method ◽  
Flow Sensitivity ◽  
Whispering Gallery ◽  
Wide Range ◽  
Novel Method ◽  
Doped Glass ◽  
Lasing Modes

Abstract We describe a novel method for making microbottle-shaped lasers by using a CO2 laser to melt Er:Yb glass onto silica microcapillaries or fibres. This is realised by the fact that the two glasses have different melting points. The CO2 laser power is controlled to flow the doped glass around the silica cylinder. In the case of a capillary, the resulting geometry is a hollow, microbottle-shaped resonator. This is a simple method for fabricating a number of glass whispering gallery mode (WGM) lasers with a wide range of sizes on a single, micron-scale structure. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fibre and WGM lasing is recorded around 1535 nm. This structure facilitates a new way to thermo-optically tune the microlaser modes by passing gas through the capillary. The cooling effect of the gas flow shifts the WGMs towards shorter wavelengths and thermal tuning of the lasing modes over 70 GHz is achieved. Results are fitted using the theory of hot wire anemometry, allowing the flow rate to be calibrated with a flow sensitivity as high as 72 GHz/sccm. Strain tuning of the microlaser modes by up to 60 GHz is also demonstrated.

Glass Microspherical Lasers

2008 ◽  
Vol 55 ◽  
pp. 46-55 ◽  
Author(s):  
Gualtiero Nunzi Conti ◽  
S. Soria ◽  
Simone Berneschi ◽  
M. Brenci ◽  
F. Cosi ◽  
...  
Keyword(s):  
Sol Gel ◽  
Laser Action ◽  
Whispering Gallery Modes ◽  
Whispering Gallery ◽  
Gel Layer ◽  
Wide Range ◽  
Evanescent Coupling ◽  
Low Threshold ◽  
Laser Sources ◽  
Doped Glass

We report experimental results obtained in our laboratories in the development of Er3+- doped glass microspherical cavities for the fabrication of compact and low threshold laser sources at 1.55 μm. We investigate three different approaches in order to fabricate the microspheres including direct melting of Er3+-doped glass powders, coating of silica microspheres with an Er3+- doped sol-gel layer, and synthesis of Er3+-doped monolithic microspheres using the sol-gel route in acid catalysis. Details of the different fabrication processes are presented together with the photoluminescence characterization in free space configuration of the microspheres and of the glass precursor. We analyse the photoluminescence spectra of the whispering gallery modes of the microspheres exited using evanescent coupling and we demonstrate laser action in a wide range of wavelengths around 1.55 μm.

scholarly journals Simple Wide Frequency Range Impedance Meter Based on AD5933 Integrated Circuit

2015 ◽  
Vol 22 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Konrad Chabowski ◽  
Tomasz Piasecki ◽  
Andrzej Dzierka ◽  
Karol Nitsch
Keyword(s):  
Integrated Circuit ◽  
Wide Frequency Range ◽  
Simple Method ◽  
Spectral Leakage ◽  
Dc Offset ◽  
Wide Range ◽  
Novel Method ◽  
And Performance ◽  
Interesting Solution ◽  
Impedance Meter

Abstract As it contains elements of complete digital impedance meter, the AD5933 integrated circuit is an interesting solution for impedance measurements. However, its use for measurements in a wide range of impedances and frequencies requires an additional digital and analogue circuitry. This paper presents the design and performance of a simple impedance meter based on the AD5933 IC. Apart from the AD5933 IC it consists of a clock generator with a programmable prescaler, a novel DC offset canceller for the excitation signal based on peak detectors and a current to voltage converter with switchable conversion ratios. The authors proposed a simple method for choosing the measurement frequency to minimalize errors resulting from the spectral leakage and distortion caused by a lack of an anti-aliasing filter in the DDS generator. Additionally, a novel method for the AD5933 IC calibration was proposed. It consists in a mathematical compensation of the systematic error occurring in the argument of the value returned from the AD5933 IC as a result. The performance of the whole system is demonstrated in an exemplary measurement.

Variable Precision Depth Encoding for 3D Range Geometry Compression

2020 ◽  
Vol 2020 (17) ◽  
pp. 34-1-34-7
Author(s):  
Matthew G. Finley ◽  
Tyler Bell
Keyword(s):  
Normal Distribution ◽  
Arbitrary Distribution ◽  
File Size ◽  
Geometry Compression ◽  
Variable Precision ◽  
Wide Range ◽  
Novel Method ◽  
Encoding Method ◽  
Rgb Image ◽  
Color Channels

This paper presents a novel method for accurately encoding 3D range geometry within the color channels of a 2D RGB image that allows the encoding frequency—and therefore the encoding precision—to be uniquely determined for each coordinate. The proposed method can thus be used to balance between encoding precision and file size by encoding geometry along a normal distribution; encoding more precisely where the density of data is high and less precisely where the density is low. Alternative distributions may be followed to produce encodings optimized for specific applications. In general, the nature of the proposed encoding method is such that the precision of each point can be freely controlled or derived from an arbitrary distribution, ideally enabling this method for use within a wide range of applications.

Expressing the Self

2018 ◽  
Keyword(s):  
Philosophy Of Mind ◽  
The Self ◽  
Epistemic Status ◽  
First Person ◽  
Semantic Categories ◽  
Wide Range ◽  
Person Reference ◽  
De Se ◽  
Novel Method ◽  
Cultural Pragmatics

This book addresses different linguistic and philosophical aspects of referring to the self in a wide range of languages from different language families, including Amharic, English, French, Japanese, Korean, Mandarin, Newari (Sino-Tibetan), Polish, Tariana (Arawak), and Thai. In the domain of speaking about oneself, languages use a myriad of expressions that cut across grammatical and semantic categories, as well as a wide variety of constructions. Languages of Southeast and East Asia famously employ a great number of terms for first-person reference to signal honorification. The number and mixed properties of these terms make them debatable candidates for pronounhood, with many grammar-driven classifications opting to classify them with nouns. Some languages make use of egophors or logophors, and many exhibit an interaction between expressing the self and expressing evidentiality qua the epistemic status of information held from the ego perspective. The volume’s focus on expressing the self, however, is not directly motivated by an interest in the grammar or lexicon, but instead stems from philosophical discussions of the special status of thoughts about oneself, known as de se thoughts. It is this interdisciplinary understanding of expressing the self that underlies this volume, comprising philosophy of mind at one end of the spectrum and cross-cultural pragmatics of self-expression at the other. This unprecedented juxtaposition results in a novel method of approaching de se and de se expressions, in which research methods from linguistics and philosophy inform each other. The importance of this interdisciplinary perspective on expressing the self cannot be overemphasized. Crucially, the volume also demonstrates that linguistic research on first-person reference makes a valuable contribution to research on the self tout court, by exploring the ways in which the self is expressed, and thereby adding to the insights gained through philosophy, psychology, and cognitive science.

scholarly journals Atmospheric Pressure Plasma Deposition of TiO2: A Review

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2931
Author(s):  
Soumya Banerjee ◽  
Ek Adhikari ◽  
Pitambar Sapkota ◽  
Amal Sebastian ◽  
Sylwia Ptasinska
Keyword(s):  
Atmospheric Pressure ◽  
Gas Flow ◽  
Plasma Deposition ◽  
Atmospheric Pressure Plasma ◽  
Cost Savings ◽  
Historical Background ◽  
Pressure Plasma ◽  
Wide Range ◽  
The Status ◽  
Deposition Techniques

Atmospheric pressure plasma (APP) deposition techniques are useful today because of their simplicity and their time and cost savings, particularly for growth of oxide films. Among the oxide materials, titanium dioxide (TiO2) has a wide range of applications in electronics, solar cells, and photocatalysis, which has made it an extremely popular research topic for decades. Here, we provide an overview of non-thermal APP deposition techniques for TiO2 thin film, some historical background, and some very recent findings and developments. First, we define non-thermal plasma, and then we describe the advantages of APP deposition. In addition, we explain the importance of TiO2 and then describe briefly the three deposition techniques used to date. We also compare the structural, electronic, and optical properties of TiO2 films deposited by different APP methods. Lastly, we examine the status of current research related to the effects of such deposition parameters as plasma power, feed gas, bias voltage, gas flow rate, and substrate temperature on the deposition rate, crystal phase, and other film properties. The examples given cover the most common APP deposition techniques for TiO2 growth to understand their advantages for specific applications. In addition, we discuss the important challenges that APP deposition is facing in this rapidly growing field.

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 Measurement and analysis of gas-puff density distributions for plasma radiation source z pinches

2001 ◽  
Vol 19 (4) ◽  
pp. 579-595 ◽  
Author(s):  
D. MOSHER ◽  
B.V. WEBER ◽  
B. MOOSMAN ◽  
R.J. COMMISSO ◽  
P. COLEMAN ◽  
...  
Keyword(s):  
Radiation Source ◽  
Gas Flow ◽  
Initial Density ◽  
High Sensitivity ◽  
Plasma Radiation ◽  
Analysis Techniques ◽  
Density Distributions ◽  
Radiation Properties ◽  
Wide Range ◽  
Measurement And Analysis

High-sensitivity interferometry measurements of initial density distributions are reviewed for a wide range of gas-puff nozzles used in plasma radiation source (PRS) z-pinch experiments. Accurate gas distributions are required for determining experimental load parameters, modeling implosion dynamics, understanding the radiation properties of the stagnated pinch, and for predicting PRS performance in future experiments. For a number of these nozzles, a simple ballistic-gas-flow model (BFM) has been used to provide good physics-based analytic fits to the measured r, z density distributions. These BFM fits provide a convenient means to smoothly interpolate radial density distributions between discrete axial measurement locations for finer-zoned two-dimensional MHD calculations, and can be used to determine how changes in nozzle parameters and load geometry might alter implosion dynamics and radiation performance. These measurement and analysis techniques are demonstrated for a nested-shell nozzle used in Double Eagle and Saturn experiments. For this nozzle, the analysis suggests load modifications that may increase the K-shell yield.

Study of Gas Flow in Micronozzles Using an Unstructured DSMC Method

2009 ◽  
Author(s):  
Ehsan Roohi ◽  
Masoud Darbandi ◽  
Vahid Mirjalili
Keyword(s):  
Boundary Layer ◽  
Knudsen Number ◽  
Gas Flow ◽  
Subsonic Flow ◽  
Flow Behavior ◽  
Boundary Layer Separation ◽  
Back Pressure ◽  
Viscous Force ◽  
Dsmc Method ◽  
Wide Range

The current research uses an unstructured direct simulation Monte Carlo (DSMC) method to numerically investigate supersonic and subsonic flow behavior in micro convergent–divergent nozzle over a wide range of rarefied regimes. The current unstructured DSMC solver has been suitably modified via using uniform distribution of particles, employing proper subcell geometry, and benefiting from an advanced molecular tracking algorithm. Using this solver, we study the effects of back pressure, gas/surface interactions (diffuse/specular reflections), and Knudsen number, on the flow field in micronozzles. We show that high viscous force manifesting in boundary layers prevents supersonic flow formation in the divergent section of nozzles as soon as the Knudsen number increases above a moderate magnitude. In order to accurately simulate subsonic flow at the nozzle outlet, it is necessary to add a buffer zone to the end of nozzle. If we apply the back pressure at the outlet, boundary layer separation is observed and a region of backward flow appears inside the boundary layer while the core region of inviscid flow experiences multiple shock-expansion waves. We also show that the wall boundary layer prevents forming shocks in the divergent part. Alternatively, Mach cores appear at the nozzle center followed by bow shocks and an expansion region.

The Pyrocarbon Deposition Techniques of Mechanical Heart Valve Prostheses

2011 ◽  
Vol 464 ◽  
pp. 749-752 ◽  
Author(s):  
Jian Hui Zhang ◽  
Xin Chen
Keyword(s):  
Fluidized Bed ◽  
Heart Valve ◽  
Gas Flow ◽  
Mechanical Heart Valve ◽  
Carbon Matrix ◽  
Artificial Heart Valve ◽  
Bed Temperature ◽  
Wide Range ◽  
Isotropic Carbon ◽  
Deposition Conditions

The structure and property of pyrocarbon varies widely with different deposition conditions. The isotropic carbon which can only been deposited in the bed of fluidized particles is very important in biomedical fields, for instance, it is often used as the coating of artificial heart valve components. The deposition of isotropic pyrocarbon containing silicon is experimented in fluidized bed over a wide range of deposition conditions. The results show that bed temperature influences strongly average coating rate, coating density, silicon content and coating micro-hardness. Propane concentration has a much effect on coating density, carbon matrix density and isotropic characteristics. Total gas flow rate and inlet dimension of fluidized bed affect the formation of fluidized bed.

Establishment of a simple method to evaluate mixing times in a plastic bag photobioreactor using image processing based on freeware tools

2021 ◽  
Author(s):  
Michael Sandmann
Keyword(s):  
Image Processing ◽  
Optical Method ◽  
Gas Flow ◽  
Mixing Time ◽  
Pearson Correlation ◽  
Mixing Times ◽  
Simple Method ◽  
Area Of Interest ◽  
Background Removal ◽  
Programming Skills

Abstract Objective The aim of this work was to develop a simple optical method to determine the mixing time in a photobioreactor. The image processing method should be based on freeware tools and should not require programming skills. Results An optical method has been established to analyze images from recorded videos of mixing experiments. The basic steps are: 1. Extraction of a sequence of images from the video file; 2. Cropping of the pictures; 3. Background removal; and 4. Image analysis and mixing time evaluation based on quantification of pixel-to-pixel heterogeneity (standard deviation over pixel intensities) within a given area of interest. The novel method was generally able to track the dependency between aeration rate and mixing time within the investigated photobioreactor. In a direct comparison, a Pearson correlation coefficient of rho = 0.9957 was obtained. Gas flow rates between 10 L h−1, and 300 L h−1 resulted from mixing times of between 48 sec and 14 sec, respectively. This simple technique is applicable even without programming skills and can be used in education within high schools and in early stages of undergraduate programs.

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