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Effects of carrier envelope phase on single shot XUV super continuum generation Mahendra Man Shakya,...
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Transcript of Effects of carrier envelope phase on single shot XUV super continuum generation Mahendra Man Shakya,...
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
as psfs10-18 s 10-15 s 10-12 s
RotationVibrationCirculation
85 eV 135 ev
Attosecond pulse train
Single attosecond pulse (250 as)
BALTU KA et al., Nature 421, 611( 2003)
•Laser pulse: 5 fs, 0.75m
What Was Before reported?Single attosecond pulse at cutoff
Elaser
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
Td
e-
e-
e-
What is the polarization gating???
p
Ellipticity dependent pulse
L45°
e-pulse o-pulse
t= L( 1ve - 1
vo)
Bing ShanOct. 2003
Quartz Plate /4 Waveplate
Ellipticity-dependent pulse
Our Method: Generation of pulseswith a time-dependent ellipticity
Using Quartz plate
Opticaxis
Opticaxis
Z. Chang, PRA (2004)
Polarization gate width : Simplified Formula and Example
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.00.0
0.2
0.4
0.6
0.8
1.0
t=1.3 fs
p=8 fs
Td=15 fs
time (fs)
d
p
Tt
2
2.0 3.0
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
MCP1
Gas Cell
Parabolic Mirror
Aluminum Filter
Retractable Mirror Diffraction
Grating
MCP2 nA
CCD2
Phase matching
35 40 45 50 55 600.0
0.2
0.4
0.6
0.8
1.0
1.28Jan06_Sun
No
rma
lize
d I
nte
nstiy
Photon Energy (eV)
5 Torr 15 25 35 45 55 65
Phase matched Plot
35 40 45 50 55 600.0
0.1
0.2
0.3
0.4
0.5
In
ten
sity (
arb
.un
it)
Photon Energy (eV)
5Torr 10Torr 15Torr 20Torr 25Torr 30Torr 35Torr 40Torr 45Torr 55Torr 60Torr
8Jan06_Sun
20Torr
30Torr
80Torr
125Torr
From phase matching pressure to phase mismatching pressure
8Jan05_Sun
35.65 38.75 41.85 45 48 51 54.25 57.35eV
55 Torr
60 Torr
Phase matching
0 20 40 60 80 100 1200.0
0.2
0.4
0.6
0.8
1.0 8Jan06_Sun
In
tens
ity (
rala
tive)
Pressure (Torr)
25th 27th 29th 31st 33rd
Measurement of half the diverging angle of the XUV beam
D=0.4cm
-10 -5 0 5 100.0
0.2
0.4
0.6
0.8
1.0
1/e2 = 3.5 mrads
No
rma
lize
d In
ten
sit
y
Divergence Angle (mrads)
8.1mrads
21.7mrads
Focus
1.35cm
Diffraction Grating
D=0.4cmW=1.3cm
W0
MCP1
Gas Cell
Parabolic Mirror
Aluminum Filter
Retractable Mirror Diffraction
Grating
MCP2 nA
CCD2
Measurement of half the diverging angle of the XUV beam
D=0.4cm
-10 -5 0 5 100.0
0.2
0.4
0.6
0.8
1.0
1/e2 = 3.5 mrads
No
rma
lize
d In
ten
sit
y
Divergence Angle (mrads)
8.1mrads
21.7mrads
Focus
1.35cm
Diffraction Grating
D=0.4cmW=1.3cm
W0
Single slit
Multi-slit
What do we expect to see with polarization gated input?? -spatial analogy
Single
electron – ion
Collision
Many
Electron-ion
Collision
-5.0 -2.5 0.0 2.5 5.0
-1.0
-0.5
0.0
0.5
1.0
-1.0
-0.5
0.0
0.5
1.0(b)
Gate
Elli
ptic
ity
Ex (
Nor
mal
ized
)
Time (fs)
CE phase Zero Degree ( Double slits analogy)
-5.0 -2.5 0.0 2.5 5.0
-1.0
-0.5
0.0
0.5
1.0
-1.0
-0.5
0.0
0.5
1.0(a)
Gate
Elli
ptic
ity
Ex (
Nor
mal
ized
)
Time (fs)
CE phase 90 Degree ( Single Slit analogy)
Linear and Long pulse ( 25fs) Harmonic spectrum
(Multi- Slits analogy)
35 40 45 50 55 600.0
0.2
0.4
0.6
0.8
1.0
Inte
nsi
ty (
arb
.un
it)
Photon Energy (eV)
Intensity2
Discrete harmonics with linear and long pulse(25fs) input
Linear and Short pulse (6fs) spectrum before polarization gating was applied
( Reduced Slit Number )
35 40 45 50 55 60
0.0
0.2
0.4
0.6
0.8
1.0
Inte
nsi
ty (
arb
.un
it)
Photon energy (eV)
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)
35 40 45 50 55 60
0.2
0.4
0.6
0.8
1.0
In
tens
ity (
arb.
unit)
Photon energy (eV)
Super continuum with polarization gated input at 100 shot (Single slit analogy)
Measurement of The Number of photons per pulse
Retractable Mirror
MCP1
Gas CellParabolic Mirror
Aluminum Filter
Diffraction Grating
MCP2 nA
CCD2
CCD1
e-nA
MCP2
Phosphor Screen
hν
Phosphor Screen
hν
MCP2
e-
nA
)8.1(04.0
8.0
)27(02.0
1.01063.5
30000
kVatAIT
HarmonicsthR
Q
G
TQRfGe
IN
Al
Al
AlAlrep
e-
20 30 400
1
2
3
4
5
-11.25o
11.25o
33.75o
56.25o
ce
=78.75o
Inte
nsity
(R
elat
ive)
Harmonic order
Effect of CE Phase Change on XUV Spectrum
22 24 26 28 30 32 34 36 380
100
200
300
400
500
600
700
Y
Axi
s T
itle
Harmonics
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
24 26 28 30 32 34 36 380
100
200
300
400
500
600
700
8002'11"
1'58"
1'38"
1'15"
0'55"
0'39"
0'21"
0'00"
Y
Axi
s T
itle
Harmonics
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 ~104 , 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
hν
MCP2
e-
nA
)8.1(04.0
8.0
)27(02.0
1.01063.5
30000
kVatAIT
HarmonicsthR
Q
G
TQRfGe
IN
Al
Al
AlAlrep
e-
Measurement of Number of photons per pulse
0
=1.3cm
D=?
Collimating mirror f = 1.5 m
Focusing mirror f = 250 mm
D=0.4cm
Required D is
D
fw0
z
zww
R
210
1.3 cm
Required D is
Required Beam Size to eliminate photon loss
w
z R02
1.3 cm
Measurement of half the diverging angle of the XUV beam
D=0.4cm
-10 -5 0 5 100.0
0.2
0.4
0.6
0.8
1.0
1/e2 = 3.5 mrads
No
rma
lize
d In
ten
sit
y
Divergence Angle (mrads)
8.1mrads
21.7mrads
Focus
1.35cm
Diffraction Grating
D=0.4cmW=1.3cm
W0