scholarly journals Optical power limiter in the femtosecond filamentation regime

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Leonidas Agiotis ◽  
Michel Meunier
Keyword(s):  
Critical Power ◽  
Optical Breakdown ◽  
Optical Power ◽  
Laser Pulses ◽  
Optical Response ◽  
Threshold Power ◽  
Spontaneous Transformation ◽  
Self Focusing ◽  
Imaging Characteristics ◽  
Femtosecond Filamentation

AbstractWe present the use of a power limiting apparatus to evaluate ultrafast optical nonlinearities of transparent liquids (water and ethanol) in the femtosecond filamentation regime. The setup has been previously employed for the same purpose, however, in a longer pulsewidth (> 20 ps) regime, which leads to an ambiguous evaluation of the critical power for self-focusing. The uncertainty originates from the existence of a threshold power for optical breakdown well below the critical power for self-focusing within this timeframe. Contrarily, using the proposed apparatus in the femtosecond regime, we observe for the first time a unique optical response, which features the underlying physics of laser filamentation. Importantly, we demonstrate a dependence of the optical transmission of the power limiter on its geometrical, imaging characteristics and the conditions under which a distinct demarcation for the critical power for self-focusing can be determined. The result is supported by numerical simulations, which indicate that the features of the observed power-dependent optical response of the power limiting setup are physically related to the spontaneous transformation of the laser pulses into nonlinear conical waves.

scholarly journals Nonlinear relativistic self-focusing of laser radiation in plasmas: Arbitrary intensity

1994 ◽  
Vol 12 (4) ◽  
pp. 623-632 ◽  
Author(s):  
M. Asthana ◽  
K.P. Maheshwari ◽  
M.S. Sodha
Keyword(s):  
Dielectric Constant ◽  
Critical Power ◽  
Laser Pulses ◽  
Density Fluctuations ◽  
Effective Dielectric Constant ◽  
Gaussian Laser Beam ◽  
Nonlinear Part ◽  
Self Focusing ◽  
Paraxial Ray ◽  
Arbitrary Intensity

A paraxial theory of relativistic self-focusing of a Gaussian laser beam in plasmas, when the nonlinear part of the effective dielectric constant is arbitrarily large, is presented. The plasma is taken to be homogeneous without any density fluctuations being necessary. The approach of Akhmanov et al. based on the WKB and paraxial ray approximations has been followed. It is seen that the saturating nature of nonlinearity leads to two values of critical power of the beam (Pcrl and Pcr2) for self-focusing. When the power of the beam P lies between the two critical values (i.e., Pcr1 < P < Pcr2), the medium behaves as an oscillatory waveguide; the beam first converges and then diverges, converges again, and so on. For P > Pcr2 the beam first diverges, then converges, then diverges, and so on. Because the relativistic mechanism is instantaneous, the theory is applicable to the understanding of selffocusing of laser pulses also.

INTERACTION OF INTENSE SHORT LASER PULSES WITH AIR AND DIELECTRIC MATERIALS

2007 ◽  
Vol 21 (03n04) ◽  
pp. 615-625 ◽  
Author(s):  
S. EISENMANN ◽  
Y. KATZIR ◽  
A. ZIGLER ◽  
G. FIBICH ◽  
E. LOUZON ◽  
...  
Keyword(s):  
Critical Power ◽  
Laser Pulses ◽  
Dielectric Materials ◽  
Laser Beams ◽  
Threshold Fluence ◽  
Short Pulses ◽  
Self Focusing ◽  
Chirped Pulses ◽  
Short Laser Pulses ◽  
Wide Gap

A study of the propagation of intense short laser pulses in air and the interaction of these pulses with distant targets is described. It is shown that the beam filamentation pattern can be controlled by introducing beam astigmatism. In addition, it is demonstrated that the collapse distance of intense femtosecond laser beams scales as P -1/2 for input powers that are moderately above the critical power for self focusing, and that at higher powers the collapse distance scales as P -1. Related to the interaction of intense short pulses with distant targets, it is measured that the threshold fluence for optical damage in wide gap materials is lower by up to 20% for negatively chirped pulses than for positively chirped, at pulse durations ranging from 60 fs to 1 ps.

scholarly journals Self-focusing limits at the laser-plasma interaction for treatment of cataract with nanosecond and picosecond pulses

1992 ◽  
Vol 10 (1) ◽  
pp. 163-178 ◽  
Author(s):  
Rosemarie H. Hora ◽  
Hans G. L. Coster ◽  
Clement J. Walter ◽  
Heinrich Hora
Keyword(s):  
Optical Breakdown ◽  
Laser Pulses ◽  
The Self ◽  
Laser Beams ◽  
Temperature Plasma ◽  
Picosecond Pulses ◽  
Laser Plasma Interaction ◽  
Self Focusing ◽  
Nanosecond Range ◽  
Transparent Area

Laser pulses are focused in the interior of a human eye in areas of opacity to produce there an optical breakdown resulting in a high-temperature plasma, after which the filling up with liquid results in a transparent area. The empirically given limits for Q-switch laser pulses in the nanosecond range and for mode-locked pulses in the picosecond range are analyzed, and it is shown that these limits are below the self-focusing condition of laser beams in plasmas. A further analysis evaluates theoretically where the maximum limits are given in order to provide the parameters for the highest possible pulse energy that avoids damage in the eye by self-focusing.

scholarly journals Relativistic Propagation of Linearly/Circularly Polarized Laser Radiation in Plasmas

ISRN Optics ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Sonu Sen ◽  
Meenu Asthana Varshney ◽  
Dinesh Varshney
Keyword(s):  
Dielectric Constant ◽  
Critical Power ◽  
Laser Pulses ◽  
Interaction Process ◽  
Laser Beams ◽  
Laser Beam Propagation ◽  
Circularly Polarized ◽  
Nonlinear Dielectric ◽  
Laser Plasma Interaction ◽  
Self Focusing

Paraxial theory of relativistic self-focusing of Gaussian laser beams in plasmas for arbitrary magnitude of intensity of the beam has been presented in this paper. The nonlinearity in the dielectric constant arises on account of relativistic variation of mass. An appropriate expression for the nonlinear dielectric constant has been used to study laser beam propagation for linearly/circularly polarized wave. The variation of beamwidth parameter with distance of propagation, self-trapping condition, and critical power has been evaluated. The saturating nature of nonlinearity yields two values of critical power of the beam ( and ) for self-focusing. When the beam diverges. When the beam first converges then diverges and so on. When the beam first diverges and then converges and so on. Numerical estimates are made for linearly/circularly polarized wave applicable for typical values of relativistic laser-plasma interaction process in underdense and overdense plasmas. Since the relativistic mechanism is instantaneous, this theory is applicable to understanding of self-focusing of laser pulses.

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