Chair: Ming-Chang Chen, National Tsing Hua University, Hsinchu, Taiwan

#14, 15:30 – 16:00 Attosecond sampling of arbitrary light waves, KYUNG TAEC KIM, KYUNGSEUNG KIM, CHUNMEI ZHANG, D. M. VILLENEUVE, P. B. CORKUM AND CHANG HEE NAM, An arbitrary optical waveform can be completely determined by measuring phase shifts of high harmonic radiation altered by an additional signal field. Since the electron motion in the process of high harmonic generation is used as a fast gate, the temporal resolution of the waveform measurement is related with the excursion time of the electron trajectory. Here we show that the waveform measurement exhibits strong wavelength dependence for short wavelength signals. Our calculations show that the signal field in the ultraviolet wavelength range can be accurately measured when the wavelength dependence of the measurement is taken into account.

#15, 16:15 – 16:30 Gating Attosecond Pulses in a Noncollinear Geometry, M. LOUISY, C.L. ARNOLD, M. MIRANDA, E.W. LARSEN, S. BENGTSSON, D. KROON, M. KOTUR, D. GUÉNOT, L. RADING, P. RUDAWSKI, F. BRIZUELA, F. CAMPI, B. KIM, A. JARNAC, A, HOUARD, J. MAURITSSON, P. JOHNSSON , A. L’HUILLIER , AND C.M. HEYL, We experimentally demonstrate that angular streaking of attosecond pulses in a noncollinear geometry is a suitable gating technique for high-order harmonic sources. Our results indicate the generation of angularly separated isolated attosecond pulses whose direction of emission can be controlled by the carrier envelope phase of the driving laser pulses. This technique is particularly suited for attosecond pump-probe measurement and intra-cavity attosecond pulse generation, as the noncollinear geometry naturally separates the fundamental driving field from the generated attosecond pulses and, as no major manipulations of the driving field are required.

#16, 16:30- 16:45 Full characterization of Attosecond Pulses Generated by Ultrafast Wavefront Rotation, TJ HAMMOND, CHUNMEI ZHANG, KYUNG TAEC KIM, GRAHAM G. BROWN, D.M. VILLENEUVE, AND P.B. CORKUM, The attosecond lighthouse is a method of using ultrafast wavefront rotation to create a series of spatially separated attosecond pulses. We present the results of two experiments, characterizing attosecond pulses generated by the lighthouse from 760nm and 1.8m sources. Photoelectron streaking is performed on the three most intense pulses generated by a kHz Ti:Sapphire laser. For longer driving wavelength, we use an in-situ measurement for spatial and spectral characterization, which is scalable to the soft X-ray spectral region. In both cases, the reconstructed, isolated pulses are compared to theory.

#17, 16:45 – 17:00 Ionization induced lighthouse effect in Ar, V. TOSA, J.S. LEE, H.T. KIM, C.H. NAM, High harmonic generation under high ionization conditions is numerically investigated. A new structure of the driving field during propagation is obtained and characterized in temporal, spectral and spatial domains. The complete depletion of neutral Ar on axis gives rise to additional wavelets which propagate with increasing divergence as the radial distances from the axis increases, generating the rotation of the propagated wavefront. We obtain attosecond bursts of light emitted with different divergences in successive optical half-cycles so that in the far field these bursts arrive at different distance from the beam axis.

#18, 17:00 – 17:15 High flux isolated attosecond pulses from non-collinear high-order harmonic generation, SHIYANG ZHONG, XINKUI HE, HAO TENG, KUN ZHAO, ZHIYI WEI, We proposed a new approach for producing high flux isolated attosecond pulses (IAPs) based on non-collinear geometry of high order harmonic generation (HHG). A main driving pulses and a short gating pulse is non-collinearly synthesized to form a rotated wavefront which leading to spatially separated IAP generation. Since the new approach no restriction on the pulse duration of the main driving pulse, it enables the present super-high energy laser could be used as driving laser for high flux IAP generation.