High Density Optical-Field-Ionization Soft X-Ray Lasers

Abstract : Generating an optical-field-ionization (OFI) collisional soft X-ray laser amplifier in a high density plasma would allow a significant increase of the saturation intensity, laser gain, and reduction of the emitted pulse duration. Due to strong refraction of the pump infrared beam in the plasma, guiding techniques have to be implemented. Using an optically preformed plasma waveguide, we successfully achieved guiding of J-energy pulses in a near-critical density krypton plasma with 50 % total transmission over 5 to 10 mm. X-ray lasing at 32.8 nm has also been demonstrated. This technique is a step towards OFI recombination soft X-ray lasers. This pumping scheme requires the production of a cold and dense plasma. We propose to pump a high density neon VIII plasma by a frequency doubled intense Ti:Sa laser. Guiding of the 405 nm pump pulse has already been achieved at LOA.