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Compression Of Laser Radiation In Plasmas Via Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Compression Of Laser Radiation In Plasmas Via Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Serge Youri Kalmykov
A train of few-laser-cycle relativistically intense radiation spikes with a terahertz repetition rate can be organized self-consistently in plasma from two frequency detuned co-propagating laser beams of low intensity. Large frequency bandwidth for the compression of spikes is produced via laser-induced periodic modulation of the plasma refractive index. The beat-wave-driven electron plasma wave downshifted from the plasma frequency creates a moving index grating thus inducing a periodic phase modulation of the driving laser (in spectral terms, electromagnetic cascading). The group velocity dispersion compresses the chirped laser beat notes to a few-cycle duration and relativistic intensity either concurrently in the same, …
Nonlinear Evolution Of The Plasma Beat Wave: Compressing The Laser Beat Notes Via Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Nonlinear Evolution Of The Plasma Beat Wave: Compressing The Laser Beat Notes Via Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Serge Youri Kalmykov
The near-resonant beat wave excitation of an electron plasma wave (EPW) can be employed for generating the trains of few-femtosecond electromagnetic (EM) pulses in rarefied plasmas. The EPW produces a comoving index grating that induces a laser phase modulation at the difference frequency. As a result, the cascade of sidebands red and blue shifted by integer multiples of the beat frequency is generated in the laser spectrum. The bandwidth of the phase-modulated laser is proportional to the product of the plasma length, laser wavelength, and amplitude of the electron density perturbation. When the beat frequency is lower than the electron …
Compression Of Laser Radiation In Plasmas Using Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Compression Of Laser Radiation In Plasmas Using Electromagnetic Cascading, Serguei Y. Kalmykov, Gennady Shvets
Serge Youri Kalmykov
Compressing high-power laser beams in plasmas via generation of a coherent cascade of electromagnetic sidebands is described. The technique requires two copropagating beams detuned by a near-resonant frequency, \Omega < \omega_{p}. The ponderomotive force of the laser beat wave drives an electron plasma wave which modifies the refractive index of plasma so as to produce a periodic phase modulation of the laser field with the beat period t_b = 2\pi/\Omega. A train of chirped laser beat notes (each of duration t_b) is thus created. The group velocity dispersion of radiation in plasma can then compress each beat note to a few-laser-cycle duration. As a result, a train of sharp electromagnetic spikes separated in time by t_b is formed. Depending on the plasma and laser parameters, chirping and compression can be implemented either concurrently in the same plasma or sequentially in different plasmas.
Application Of Detuned Laser Beatwave For Generation Of Few-Cycle Electromagnetic Pulses, Serguei Y. Kalmykov, Gennady Shvets
Application Of Detuned Laser Beatwave For Generation Of Few-Cycle Electromagnetic Pulses, Serguei Y. Kalmykov, Gennady Shvets
Serge Youri Kalmykov
An approach to compressing high-power laser beams in plasmas via coherent Raman sideband generation is described. The technique requires two beams: a pump and a probe detuned by a near-resonant frequency \Omega < \omega_p. The two laser beams drive a high-amplitude electron plasma wave (EPW) which modifies the refractive index of plasma so as to produce a periodic phase modulation of the incident laser with the laser beat period t_b = 2\pi / \Omega. After propagation through plasma, the original laser beam breaks into a train of chirped beatnotes (each of duration t_b). The chirp is positive (the longer-wavelength sidebands are advanced in time) when \Omega < \omega_p and negative otherwise. Finite group velocity dispersion (GVD) of radiation in plasma can compress the positively chirped beatnotes to a few-laser-cycle duration thus creating in plasma a sequence of sharp electromagnetic spikes separated in time by t_b. Driven EPW strongly couples the laser sidebands and thus reduces the effect of GVD. Compression of the chirped beatnotes can be implemented in a separate plasma of higher density, where the laser sidebands become uncoupled.