Yield and temporal characterization of high-order harmonics from intense midinfrared excitation of a cesium vapor

T. O. Clatterbuck, Brookhaven National Laboratory
C. Lyngå, Brookhaven National Laboratory
P. M. Paul, Brookhaven National Laboratory
L. F. DiMauro, Brookhaven National Laboratory
M. B. Gaarde, Louisiana State University
K. J. Schafer, Louisiana State University
P. Agostini, Commissariat a L'Energie Atomique CEA
K. C. Kulander, Lawrence Livermore National Laboratory
I. Walmsley, University of Oxford


Cesium vapor produced high harmonic radiation in the visible/UV spectral range when interacting with a tightly focused, intense midinfrared source. It was found that the measured yields of harmonic orders 9-17 yielded quantitative agreement with numerical simulations. Using an autocorrelation method, the 5th-9th harmonic orders were generated with sufficient pulse energies for direct temporal measurements. The cause of the spectral broadening was found to be a blueshift connected to a strong time-dependent ionization.