scholarly journals First Observations of Narrowband Stimulated Electromagnetic Emissions at the Pump Frequency Second Harmonic During Ionosphere Interaction Experiments

2018 ◽  
Vol 45 (16) ◽  
pp. 8690-8697 ◽  
Author(s):  
A. D. Yellu ◽  
W. A. Scales ◽  
A. Mahmoudian ◽  
P. A. Bernhardt ◽  
C. L. Siefring ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Pump Frequency ◽  
Electromagnetic Emissions

scholarly journals Pump Power Effects on Second Harmonic Stimulated Electromagnetic Emissions During Ionosphere Heating

2019 ◽  
Vol 124 (11) ◽  
pp. 9739-9754 ◽  
Author(s):  
A. D. Yellu ◽  
W. A. Scales ◽  
A. Mahmoudian ◽  
P. A. Bernhardt ◽  
C. L. Siefring ◽  
...  
Keyword(s):  
Pump Power ◽  
Second Harmonic ◽  
Electromagnetic Emissions ◽  
Ionosphere Heating

scholarly journals Second harmonic generation of q-Gaussian laser beam in plasma channel created by ignitor heater technique

2019 ◽  
Vol 37 (2) ◽  
pp. 184-196 ◽  
Author(s):  
Naveen Gupta
Keyword(s):  
Second Harmonic Generation ◽  
Laser Beam ◽  
Harmonic Generation ◽  
Plasma Channel ◽  
Second Harmonic ◽  
Laser Beams ◽  
Theory Approach ◽  
Gaussian Laser Beam ◽  
Incident Laser ◽  
Pump Frequency

AbstractThis paper presents a scheme for second harmonic generation (SHG) of q-Gaussian laser beam in plasma channel created by ignitor heater technique. The ignitor beam creates plasma by tunnel ionization of air. The heater beam heats the plasma electrons and establishes a parabolic density profile. The third beam (q-Gaussian beam) is guided in this plasma channel under the combined effects of density nonuniformity of the plasma channel and relativistic mass nonlinearity of the plasma electrons. The propagation of q-Gaussian laser beam through the plasma channel excites an electron plasma wave at pump frequency that interacts with the incident laser beam to produce its second harmonics. The formulation is based on finding the numerical solution of the nonlinear Schrodinger wave equation for the fields of the incident laser beams with the help of moment theory approach. Particular emphasis is put on dynamical variations of the spot size of the laser beams and conversion efficiency of the second harmonics with distance of propagation.

scholarly journals Generation of Second Harmonics of Relativistically Self-Focused q-Gaussian Laser Beams in Underdense Plasma with Axial Density Ramp

2021 ◽  
Author(s):  
Naveen Gupta ◽  
Sandeep Kumar
Keyword(s):  
Laser Beam ◽  
Plasma Wave ◽  
Pump Beam ◽  
Second Harmonic ◽  
Fluid Model ◽  
Intense Laser ◽  
Laser Beams ◽  
Variational Theory ◽  
Plasma Parameters ◽  
Pump Frequency

Abstract An investigation on frequency doubling of intense laser beams through the phenomenon of second harmonic generation (SHG) in underdense plasmas has been presented. In order to increase the efficiency of S.H.G the density profile of plasma has been considered in the shape of upward ramp. When laser beam with frequency !0 propagates through plasma, it makes the plasma electrons to oscillate at pump frequency. These oscillations of plasma electrons in the presence of thermal velocity generate a plasma wave at frequency !0. The generated plasma wave beats with the pump beam to double its frequency. Variational theory has been adopted to find semi analytical solution of the wave equation for the slowly varying envelope of the laser beam. By using hydrodynamic fluid model of plasma, nonlinear current density for SHG has been obtained. Emphasis are put on investigation of the effect of various laser and plasma parameters on propagation dynamics of pump beam and the power of generated second harmonics.

scholarly journals Optical Frequency Combs in Quadratically Nonlinear Resonators

Micromachines ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 230 ◽  
Author(s):  
Iolanda Ricciardi ◽  
Simona Mosca ◽  
Maria Parisi ◽  
François Leo ◽  
Tobias Hansson ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Frequency Comb ◽  
Second Harmonic ◽  
Theoretical Work ◽  
Optical Frequency ◽  
Pump Frequency ◽  
Optical Frequency Combs ◽  
Frequency Combs ◽  
New Class ◽  
Parametric Processes

Optical frequency combs are one of the most remarkable inventions in recent decades. Originally conceived as the spectral counterpart of the train of short pulses emitted by mode-locked lasers, frequency combs have also been subsequently generated in continuously pumped microresonators, through third-order parametric processes. Quite recently, direct generation of optical frequency combs has been demonstrated in continuous-wave laser-pumped optical resonators with a second-order nonlinear medium inside. Here, we present a concise introduction to such quadratic combs and the physical mechanism that underlies their formation. We mainly review our recent experimental and theoretical work on formation and dynamics of quadratic frequency combs. We experimentally demonstrated comb generation in two configurations: a cavity for second harmonic generation, where combs are generated both around the pump frequency and its second harmonic and a degenerate optical parametric oscillator, where combs are generated around the pump frequency and its subharmonic. The experiments have been supported by a thorough theoretical analysis, aimed at modelling the dynamics of quadratic combs, both in frequency and time domains, providing useful insights into the physics of this new class of optical frequency comb synthesizers. Quadratic combs establish a new class of efficient frequency comb synthesizers, with unique features, which could enable straightforward access to new spectral regions and stimulate novel applications.

scholarly journals Exponential density transition-based enhanced second harmonic generation in plasma

2018 ◽  
Vol 36 (3) ◽  
pp. 363-368 ◽  
Author(s):  
Vishal Thakur ◽  
Niti Kant
Keyword(s):  
Magnetic Field ◽  
Second Harmonic Generation ◽  
Plasma Density ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Focal Region ◽  
Pump Frequency ◽  
Self Focusing ◽  
Exponential Density ◽  
Wiggler Magnetic Field

AbstractEnhanced harmonic generation of second order based on exponential density ramp in plasma has been noticed. It is well known that self-focusing of pump laser induces a transverse intensity gradient, which gives rise to the plasma wave at the pump frequency. Highly intense Gaussian laser with exponential density ramp profile generates a second harmonic pulse in plasma. It is noticed that the amplitude of second-harmonic pulse varies periodically with the distance and reaches its peak value in the focal region. Further, it is found that exponential plasma density ramp is useful for stronger self-focusing, which lead to rise second harmonic generation (SHG). Wiggler magnetic field provides the additional angular momentum required for second harmonic photon and aids in growing of resonant process. One may clearly see that exponential plasma density ramp imparts a major role in enhancing the SHG in plasma. Further, the combined effect of exponential density ramp and wiggler magnetic field boosts the SHG in plasma.

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