Effects of carrier envelope phase on single shot XUV super continuum generation Mahendra Man Shakya, Steve Gilbertson, Chris Nakamura, Chengquan Li, Eric Moon, Zuoliang Duan, Janson Tacket, Shambhu Ghimire and Zenghu Chang 200

Why do we need attosecond pulses? Time asps fs s s s RotationVibration Circulation

85 eV135 ev Attosecond pulse train Single attosecond pulse (250 as) BALTU KA et al., Nature 421, 611( 2003) Laser pulse: 5 fs, 0.75  m What Was Before reported? Single attosecond pulse at cutoff E laser t

Our Goal To study dynamics of electron in atoms and molecules using pump-probe technique with the pulse as short as 25 attosecond (one atomic unit) generated from plateau region of XUV spectrum. To Study effect of CE phase change on the dynamics of electrons in atoms. To determine the absolute CE phase from XUV Spectrum

f-2f set up measures the relative CE phase change. But it is possible to determine absolute phase from XUV by investigating shot to shot variation of CE phase with polarization gated input. What is the advantage of XUV single shot over f-2f spectrometer ?

V. T. Platonenko and V. V. Strelkov J. Opt. Soc. Am. B 16, 435 (1999) Left Circular Pulse Right Circular Pulse TdTd e-e- e-e- e-e- What is the polarization gating??? Ellipticity dependent pulse

Quartz Plate /4 Waveplate Ellipticity-dependent pulse Our Method: Generation of pulses with a time-dependent ellipticity Using Quartz plate Optic axis Optic axis

Z. Chang, PRA (2004) Polarization gate width : Simplified Formula and Example

Major problem: Less number of photons Phase Matched Pressure. Small Diverging Angle of XUV Aluminum Filter Shield (Design) Our Effort:

Our Design: Higher Efficiency CCD1

Phase matching

Phase matched Plot

20Torr 30Torr 80Torr 125Torr From phase matching pressure to phase mismatching pressure 8Jan05_Sun eV 55 Torr 60 Torr

Phase matching

Measurement of half the diverging angle of the XUV beam D=0.4cm 8.1mrads 21.7mrads Focus 1.35cm Diffraction Grating D=0.4cm W=1.3cm W0W0

Measurement of half the diverging angle of the XUV beam D=0.4cm 8.1mrads 21.7mrads Focus 1.35cm Diffraction Grating D=0.4cm W=1.3cm W0W0

Single slit Multi-slit What do we expect to see with polarization gated input?? -spatial analogy Single electron – ion Collision Many Electron-ion Collision

CE phase Zero Degree ( Double slits analogy)

CE phase 90 Degree ( Single Slit analogy)

Linear and Long pulse ( 25fs) Harmonic spectrum (Multi- Slits analogy)

Discrete harmonics with linear and long pulse(25fs) input

Linear and Short pulse (6fs) spectrum before polarization gating was applied ( Reduced Slit Number )

Discrete but broad spectral width with linear 6fs input before gating( reduced slit analogy)

Super continuum with Polarization Gated input at 100 shots (Single Slit Analogy)

Super continuum with polarization gated input at 100 shot (Single slit analogy)

Measurement of The Number of photons per pulse Retractable Mirror MCP1 Gas Cell Parabolic Mirror Aluminum Filter Diffraction Grating MCP2 nA CCD2 CCD1 e- nA MCP2 Phosphor Screen hνhν hνhν MCP2 e- nA e-

Effect of CE Phase Change on XUV Spectrum

2’28” 2’20” 1’23” 1’06” 0’50” 0’35” 0’17” 0’0” Single shot spectrum with CE phase unlocked

4Dec05_Sun Single Shot Super continuum with CE Phase locked

Summary Dependence of the photon flux of polarization gated high harmonics on the target gas pressure was investigated. Highest number of photons was estimated to be ~10 4, which was enough to run single shot experiment. We observed effect of CE phase on XUV spectra, which could be applied as a “phase meter”.

Phosphor Screen hνhν MCP2 e- nA e- Measurement of Number of photons per pulse

=1.3cm D=? Collimating mirror f = 1.5 m Focusing mirror f = 250 mm D=0.4cm Required D is 1.3 cm Required D is Required Beam Size to eliminate photon loss 1.3 cm

Measurement of half the diverging angle of the XUV beam D=0.4cm 8.1mrads 21.7mrads Focus 1.35cm Diffraction Grating D=0.4cm W=1.3cm W0W0