Wave impedance of the linear resonant gain medium characterized by a Doppler broadened Lorentz line

1977 ◽  
Vol 65 (8) ◽  
pp. 1215-1217 ◽  
Author(s):  
H. Gamo
Keyword(s):  
Wave Impedance ◽  
Gain Medium ◽  
Lorentz Line

Apparent Superluminal Propagation of a Laser Pulse in a Gain Medium

2001 ◽  
Author(s):  
Phillip Sprangle ◽  
Joseph Penano ◽  
Bahman Hafizi
Keyword(s):  
Laser Pulse ◽  
Gain Medium ◽  
Superluminal Propagation

GeSn Lasers with Uniaxial Tensile Strain in the Gain Medium

2019 ◽  
Author(s):  
Mathieu Bertrand ◽  
Francesco Armand Pilon ◽  
Vincent Reboud ◽  
Hans Sigg ◽  
Quang-Minh Thai ◽  
...  
Keyword(s):  
Tensile Strain ◽  
Gain Medium ◽  
Uniaxial Tensile

scholarly journals Amplification by stimulated emission of nitrogen-vacancy centres in a diamond-loaded fibre cavity

Nanophotonics ◽  
2020 ◽  
Vol 9 (15) ◽  
pp. 4505-4518
Author(s):  
Sarath Raman Nair ◽  
Lachlan J. Rogers ◽  
Xavier Vidal ◽  
Reece P. Roberts ◽  
Hiroshi Abe ◽  
...  
Keyword(s):  
Room Temperature ◽  
Gain Medium ◽  
Stimulated Emission ◽  
Nitrogen Vacancy ◽  
Qualitative Model ◽  
Seed Laser ◽  
Laser Threshold ◽  
Cavity System ◽  
Emission Changes ◽  
532 Nm

AbstractLaser threshold magnetometry using the negatively charged nitrogen-vacancy (NV−) centre in diamond as a gain medium has been proposed as a technique to dramatically enhance the sensitivity of room-temperature magnetometry. We experimentally explore a diamond-loaded open tunable fibre-cavity system as a potential contender for the realisation of lasing with NV− centres. We observe amplification of the transmission of a cavity-resonant seed laser at 721 nm when the cavity is pumped at 532 nm and attribute this to stimulated emission. Changes in the intensity of spontaneously emitted photons accompany the amplification, and a qualitative model including stimulated emission and ionisation dynamics of the NV− centre captures the dynamics in the experiment very well. These results highlight important considerations in the realisation of an NV− laser in diamond.

scholarly journals A GPR-Based Pavement Density Profiler: Operating Principles and Applications

2021 ◽  
Vol 13 (13) ◽  
pp. 2613
Author(s):  
Nectaria Diamanti ◽  
A. Peter Annan ◽  
Steven R. Jackson ◽  
Dylan Klazinga
Keyword(s):  
Asphalt Pavement ◽  
Wave Impedance ◽  
Asphalt Mixtures ◽  
Void Content ◽  
Air Voids ◽  
New Instrument ◽  
Pavement Engineering ◽  
And Performance ◽  
Air Void ◽  
Air Void Content

Density is one of the most important parameters in the construction of asphalt mixtures and pavement engineering. When a mixture is properly designed and compacted, it will contain enough air voids to prevent plastic deformation but will have low enough air void content to prevent water ingress and moisture damage. By mapping asphalt pavement density, areas with air void content outside of the acceptable range can be identified to predict its future life and performance. We describe a new instrument, the pavement density profiler (PDP) that has evolved from many years of making measurements of asphalt pavement properties. This instrument measures the electromagnetic (EM) wave impedance to infer the asphalt pavement density (or air void content) locally and over profiles.

scholarly journals In-situ monitoring for liquid metal jetting using a millimeter-wave impedance diagnostic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tammy Chang ◽  
Saptarshi Mukherjee ◽  
Nicholas N. Watkins ◽  
David M. Stobbe ◽  
Owen Mays ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Millimeter Wave ◽  
Manufacturing Systems ◽  
Wave Impedance ◽  
In Situ Monitoring ◽  
Full Wave ◽  
Drop On Demand ◽  
The Time Domain ◽  
Metal Droplets

AbstractThis article presents a millimeter-wave diagnostic for the in-situ monitoring of liquid metal jetting additive manufacturing systems. The diagnostic leverages a T-junction waveguide device to monitor impedance changes due to jetted metal droplets in real time. An analytical formulation for the time-domain T-junction operation is presented and supported with a quasi-static full-wave electromagnetic simulation model. The approach is evaluated experimentally with metallic spheres of known diameters ranging from 0.79 to 3.18 mm. It is then demonstrated in a custom drop-on-demand liquid metal jetting system where effective droplet diameters ranging from 0.8 to 1.6 mm are detected. Experimental results demonstrate that this approach can provide information about droplet size, timing, and motion by monitoring a single parameter, the reflection coefficient amplitude at the input port. These results show the promise of the impedance diagnostic as a reliable in-situ characterization method for metal droplets in an advanced manufacturing system.

scholarly journals Modeling and Measurement of Thermal Effect in a Flashlamp-Pumped Direct-Liquid-Cooled Split-Disk Nd:LuAG Ceramic Laser Amplifier

Photonics ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 97
Author(s):  
Shengzhe Ji ◽  
Wenfa Huang ◽  
Tao Feng ◽  
Long Pan ◽  
Jiangfeng Wang ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Thermal Effects ◽  
Thermal Deformation ◽  
High Energy ◽  
Gain Medium ◽  
Wavefront Aberration ◽  
Experimental Measurements ◽  
Laser Amplifier ◽  
Design And Optimization ◽  
Ceramic Laser

In this paper, a model to predict the thermal effects in a flashlamp-pumped direct-liquid-cooled split-disk Nd:LuAG ceramic laser amplifier has been presented. In addition to pumping distribution, the model calculates thermal-induced wavefront aberration as a function of temperature, thermal stress and thermal deformation in the gain medium. Experimental measurements are carried out to assess the accuracy of the model. We expect that this study will assist in the design and optimization of high-energy lasers operated at repetition rate.

A new strategy to reduce edge chipping using stress wave impedance matching

CIRP Annals ◽  
2021 ◽  
Author(s):  
Yifan Zhang ◽  
Yuyang Zhao ◽  
Jundong Xu ◽  
Mengqi Rao ◽  
Yuehong Yin
Keyword(s):  
Stress Wave ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Edge Chipping ◽  
New Strategy

scholarly journals Optimization of spaceflight millimeter-wave impedance matching networks using laser trimming

2021 ◽  
pp. 1-7
Author(s):  
K. Parow-Souchon ◽  
D. Cuadrado-Calle ◽  
S. Rea ◽  
M. Henry ◽  
M. Merritt ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Millimeter Wave ◽  
Impedance Matching ◽  
Wave Impedance ◽  
Low Noise ◽  
Device Performance ◽  
Interface Circuits ◽  
Interface Circuit ◽  
Noise Amplifier

Abstract Realizing packaged state-of-the-art performance of monolithic microwave integrated circuits (MMICs) operating at millimeter wavelengths presents significant challenges in terms of electrical interface circuitry and physical construction. For instance, even with the aid of modern electromagnetic simulation tools, modeling the interaction between the MMIC and its package embedding circuit can lack the necessary precision to achieve optimum device performance. Physical implementation also introduces inaccuracies and requires iterative interface component substitution that can produce variable results, is invasive and risks damaging the MMIC. This paper describes a novel method for in situ optimization of packaged millimeter-wave devices using a pulsed ultraviolet laser to remove pre-selected areas of interface circuit metallization. The method was successfully demonstrated through the optimization of a 183 GHz low noise amplifier destined for use on the MetOp-SG meteorological satellite series. An improvement in amplifier output return loss from an average of 12.9 dB to 22.7 dB was achieved across an operational frequency range of 175–191 GHz and the improved circuit reproduced. We believe that our in situ tuning technique can be applied more widely to planar millimeter-wave interface circuits that are critical in achieving optimum device performance.

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