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High-harmonic generation from noble gases exposed to intense laser fields. Gavin Waters Supervisor: Dr. L. J. Frasinski. Schematic Diagram of Equipment. Three-step Model of HHG. Step 1: Tunnel ionization Step 2: Quasi-classical electron acceleration in strong laser field
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High-harmonic generation from noble gases exposed to intense laser fields Gavin Waters Supervisor: Dr. L. J. Frasinski
Schematic Diagram of Equipment Diagram: Y. Mairesse et al; 'Attosecond Synchronization of High-Harmonic Soft X-rays' Science, Vol 302, 28 November 2003, 1540-1543
Three-step Model of HHG Step 1: Tunnel ionization Step 2: Quasi-classical electron acceleration in strong laser field Step 3: Electron-nucleus recombination, emission of High Harmonic photon Due to this process occurring every half of the optical cycle of the driving beam, only photons of frequency that are odd harmonics of the driving beam are produced Diagram: P. Agostini, L. F. DiMauro; 'The Physics of Attosecond Light Pulses' Rep. Prog. Phys. 67 (2004) 813-855
Electron Wave-packet Model of HHG Electron now represented by its wave-function, ψ Part of the wave-function, ψg, remains in the ground state Remaining part of wave-function, ψc, interferes with ψg on re-collision This interference effect leads to an electron charge oscillation, and the emission of High Harmonic radiation Diagram: J. Itatani et al; ' Tomographic Imaging of Molecular Orbitals' Nature, Vol 432, 16 December 2004, 867-871
Technical Drawing of Apparatus Side view of the HHG equipment. Equipment designed by J. Tisch (Imperial College). The two main components shown are HHG chamber (right) and mirror chamber (left). Diagram: J. Tisch, Imperial College
Technical Drawing of Apparatus Top down view of the HHG equipment. Red line represents driving laser beam (pulse duration about 30fs). Green line represents HHG laser beam (pulse duration less than 1fs). Diagram: J. Tisch, Imperial College