Polarization control of high order harmonics in the EUV photon energy range.

We report the generation of circularly polarized high order harmonics in the extreme ultraviolet range (18-27 nm) from a linearly polarized infrared laser (40 fs, 0.25 TW) focused into a neon filled gas cell. To circularly polarize the initially linearly polarized harmonics we have implemented a four-reflector phase-shifter. Fully circularly polarized radiation has been obtained with an efficiency of a few percents, thus being significantly more efficient than currently demonstrated direct generation of elliptically polarized harmonics. This demonstration opens up new experimental capabilities based on high order harmonics, for example, in biology and materials science. The inherent femtosecond time resolution of high order harmonic generating table top laser sources renders these an ideal tool for the investigation of ultrafast magnetization dynamics now that the magnetic circular dichroism at the absorption M-edges of transition metals can be exploited.

[1]  David Garzella,et al.  Injection of harmonics generated in gas in a free-electron laser providing intense and coherent extreme-ultraviolet light , 2008 .

[2]  J W McConkey,et al.  Production and measurement of circular polarization in the VUV. , 1985, Applied optics.

[3]  Constance Valentin,et al.  An optimized kHz two-colour high harmonic source for seeding free-electron lasers and plasma-based soft x-ray lasers , 2009 .

[4]  Sophie Kazamias,et al.  Submicrometer digital in-line holographic microscopy at 32 nm with high-order harmonics. , 2006, Optics letters.

[5]  Roman Tatchyn,et al.  The LCLS: A fourth generation light source using the SLAC linac , 1995 .

[6]  Martin Aeschlimann,et al.  Ultrafast demagnetization dynamics at the M edges of magnetic elements observed using a tabletop high-harmonic soft x-ray source. , 2009, Physical review letters.

[7]  M. Murnane,et al.  Elliptically polarized high-order harmonic emission from molecules in linearly polarized laser fields. , 2009, Physical review letters.

[8]  Ivanov,et al.  Theory of high-harmonic generation by low-frequency laser fields. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[9]  F. Krausz.  Attosecond Physics , 2007, 2007 Conference on Lasers and Electro-Optics - Pacific Rim.

[10]  Ivanov,et al.  High-harmonic generation and correlated two-electron multiphoton ionization with elliptically polarized light. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[11]  Paolo Villoresi,et al.  High-order laser harmonics and synchrotron study of transition metals M 2,3 edges , 2006 .

[12]  H. Wabnitz,et al.  The soft x-ray free-electron laser FLASH at DESY: beamlines, diagnostics and end-stations , 2009 .

[13]  P. Bucksbaum,et al.  Measurement of the polarization state of high harmonics generated in gases , 1996 .

[14]  M. Skibowski,et al.  Determination of the ellipticity of light and of optical constants by use of two reflection polarizers. , 1971, Applied optics.

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

[16]  David L. Windt,et al.  IMD—software for modeling the optical properties of multilayer films , 1998 .

[17]  Hartmut Höchst,et al.  Multiple-reflection λ4 phase shifter: A viable alternative to generate circular-polarized synchrotron radiation , 1994 .

[18]  Henry C. Kapteyn,et al.  High-harmonic generation: Ultrafast lasers yield X-rays , 2010 .

[19]  Philippe Balcou,et al.  Probing coherently excited optical phonons by extreme ultraviolet radiation with femtosecond time resolution , 2008 .