Fourier-limited seeded soft x-ray laser pulse.

We present what we believe to be the first measurement of the spectral properties of a soft x-ray laser seeded by a high-order harmonic beam. Using an interferometric method, the spectral profile of a seeded Ni-like krypton soft x-ray laser (32.8 nm) generated by optical field ionization has been experimentally determined, and the shortest possible pulse duration has been deduced. The source exhibits a Voigt spectral profile with an FWHM of 3.1+/-0.3 mA, leading to a Fourier-transform pulse duration of 4.7 ps. This value is comparable with the upper limit of the soft x-ray pulse duration determined by experimentally investigating the gain dynamics, from which we conclude that the source has reached the Fourier limit. The measured bandwidth is in good agreement with the predictions of a radiative transfer code, including gain line narrowing and saturation rebroadening.

[1]  T. Mocek,et al.  A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam , 2004, Nature.

[2]  K. Cassou,et al.  Longitudinal coherence and spectral profile of a nickel-like silver transient soft X-ray laser , 2006 .

[3]  Akira Sasaki,et al.  Direct measurement of the temporal profile of the amplification gain of the transient collisional excitation neonlike manganese x-ray laser medium , 2007 .

[4]  A Carillon,et al.  Demonstration of a Ni-like Kr optical-field-ionization collisional soft x-ray laser at 32.8 nm. , 2002, Physical review letters.

[5]  Tomas Mocek,et al.  Characterization of the collisionally pumped optical-field-ionized soft-x-ray laser at 41.8 nm driven in capillary tubes , 2006 .

[6]  Underwood,et al.  Experimental and theoretical investigation of neonlike selenium x-ray laser spectral linewidths and their variation with amplification. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[7]  Karol A. Janulewicz,et al.  Amplification of a high-order harmonic pulse in an active medium of a plasma-based x-ray laser , 2009 .

[8]  A Klisnick,et al.  Dynamical description of transient x-ray lasers seeded with high-order harmonic radiation through Maxwell-Bloch numerical simulations. , 2007, Physical review letters.

[9]  Barbara Gayraud-Morel,et al.  Mrf4 determines skeletal muscle identity in Myf5:Myod double-mutant mice , 2004, Nature.

[10]  Tomas Mocek,et al.  Determination of the Ion Temperature in a Plasma Created by Optical Field Ionization , 2007 .

[11]  Klein,et al.  Frequency-fluctuation model for line-shape calculations in plasma spectroscopy. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[12]  Jorge J. Rocca,et al.  Measurement of 1-ps soft-x-ray laser pulses from an injection-seeded plasma amplifier , 2009 .

[13]  Yong Wang,et al.  Phase-coherent, injection-seeded, table-top soft-X-ray lasers at 18.9 nm and 13.9 nm , 2008 .