Development of a New Type of Ultra-Powerful Compact Femtosecond Laser
Ultra-high intensity and ultra-short pulse laser via Raman amplification and compression in plasmas
Stimulated Raman backscattering (RBS) can be pictured as an incident electromagnetic wave with frequency, w1, resonantly decaying into a longitudinal plasma wave (Langmuir wave) with plasma frequency, wp , and a scattered electromagnetic wave with frequency ,w2. A weak short seed laser pulse can be amplified by a long counter-propagating pump pulse through this plasma mediated three-wave interaction process.
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A Very high intensity of the amplified pulse can be achieved when the resonant Raman backscattering amplification process is operated in the nonlinear regime, where pump depletion is accompanied by the temporal compression of the amplified pulse. The energy transferred from pump to seed is proportional to their frequencies, and with wpump³ 10wpe, the efficiency can be as high as 90%.
Current work focuses on building a very compact, table-top, low cost (without any expensive optical elements in the system) Raman amplifier with high energy transfer efficiency from pump to seed. Very high output intensities in the order of ~ 1020 W/cm2 are expected to be obtained in the near future. By using a significantly larger pump laser and a larger size plasma (larger diameter and length) intensities in the order of 1025 W/cm2 can be reachable from our system, as well.