High-harmonic generation from noble gases exposed to intense laser fields Gavin Waters Supervisor:...

Diagram: P. Agostini, L. F. DiMauro; 'ThDiagram: P. Agostini, L. F. DiMauro; 'The Physics of Attosecond Light Pulses' Re Physics of Attosecond Light Pulses' Rep. Prog. Phys. 67 (2004) 813-855ep. Prog. Phys. 67 (2004) 813-855

High-harmonic generation High-harmonic generation from noble gases exposed from noble gases exposed

to intense laser fieldsto intense laser fields

Gavin WatersGavin Waters

Supervisor: Dr. L. J. FrasinskiSupervisor: Dr. L. J. Frasinski

Diagram: Y. Mairesse et al; 'AttoseconDiagram: Y. Mairesse et al; 'Attosecond Synchronization of High-Harmonic Sd Synchronization of High-Harmonic Soft X-rays' Science, Vol 302, 28 Noveoft X-rays' Science, Vol 302, 28 November 2003, 1540-1543 mber 2003, 1540-1543

Schematic Diagram of Equipment Schematic Diagram of Equipment


Three-step Model of HHGThree-step Model of HHGStep 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: J. Itatani et al; ' TomographicDiagram: J. Itatani et al; ' Tomographic Imaging of Molecular Orbitals' Nature, Imaging of Molecular Orbitals' Nature, Vol 432, 16 December 2004, 867-871 Vol 432, 16 December 2004, 867-871

Electron Wave-packet Model of Electron Wave-packet Model of HHGHHG

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. Tisch, Imperial CollegeDiagram: J. Tisch, Imperial College

Technical Drawing of Technical Drawing of ApparatusApparatus

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 CollegeDiagram: J. Tisch, Imperial College

Technical Drawing of Technical Drawing of ApparatusApparatus

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).


HHG equipment used in Saclay HHG equipment used in Saclay experimentexperiment


Mirror Chamber used in Saclay Mirror Chamber used in Saclay ExperimentExperiment


ULL, University of ReadingULL, University of Reading

High-harmonic generation from noble gases exposed to intense laser fields Gavin Waters Supervisor:...

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