Transcript Application, limitation, and distortion of single

Distortion of single-shot EO
sampling techniques in measuring
particle beam profiles
and SR application
Yuelin Li
Accelerator Systems Division
Argonne National Laboratory
ICFA: Frontiers of Short Bunches in Storage Rings
Frascati, Italy, Nov. 7-8, 2005
Argonne National Laboratory is managed by
The University of Chicago for the U.S. Department of Energy
Acknowlegement




K. -J. Kim, K. Harkay, moral, financial support
J. Wang, E. Landahl, real estate surpport
P. Bolton, X. Zhang, helpful discussion
Work supported by the U. S. Department of Energy, Office of Basic
Energy Sciences, Contract No. W-31-109-ENG-38.
2
Measuring ultrashort electron beam using electro optical
sampling
Laser
(001)
y
p
x
E
p
z (110)
E beam
Probe laser
P1
P2
1
nx , y  n  n 3 Er41
2
2n3 Er41l

~ 7.27 10 4 El

1
I   I p [1  cos( r   )]  ( r   ) 2 ,
2
I //  I p [1  cos( r   )].
e beam
r: crystal residual or bias
birefringence.
3
EO history and its application in beam measurement



Observation of optical rectification, 1962
Bass et al., PRL 9, 446 (1962)
Demonstration of picosecond optical sampling, 1982
Valadmanis et al, APL 41, 212, (1982)
Demonstration of single-shot EO techniques, 2000Chirped laser pulse, Jiang and Zhang, APL 72, 1945 (1998)
THz/Probe correlation, Shan et al, OL 25, 426 (2000)
Double correlation, Jamison et al, OL 28, 1710 (2003)
FROG EO: proposed by Bolton (2002)
 Application in beam measurement, 1998–
–
–
–
–
FNAL and BNL: 100 ps- ns temporal resolution
FELIX: Yan et al., PRL 85, 3404 (2000);
FELIX: Wilke et al., PRL 88, 124801 (2002), 2 ps
FELIX: Berden et al., PRL 93, 114802 (2004), 300 fs
SLAC/SPPS: Cavalieri et al., PRL 94, 114801 (2005), 300
fs
4
What’s left?

Choice of single-shot techniques
–
–
–

Distortions and corrections for precision measurement
–
–
–

Identification of distortion effects
Crystal orientation?
Known effect: group velocity mismatch, crystal response
Better temporal resolution
–

Chirped probe pulse mapping
Probe laser cross correlation
“Real” time-resolved
Physical limit: crystal response and choice of techniques
Application beyond short bunch measurement for linac beam
–
Scenario for SR applications
5
Off-line EO testing experiment
 Replace the particle beam with an EM impulse, i.e., THz pulse
Probe laser
P1
Probe laser
P2
P1
P2
Pump laser
e beam
THz
 Differences from a THz experiment
– Particle beam fields has a zero carrier frequency
– Particle beam may deliver much higher field strength
– Particle beams require single-shot measurement
6
Experiment setup
Adjustment optical bias r
I   I p [1  cos( r   )],
Pump/Probe duration: 70 fs
I //  I p [1  cos( r   )].
Pump Energy: 0.8 mJ/pulse
Probe: 0.08 mJ/pulse
Adjustment of sampling crystal angle
Shan et al, Opt Lett 25, 426 (2000).
0.28 ps
Adjustment of pump intensity

ETHz () 
  (,  )G(,  , l )E
pump
( ) E *pump (  )d

 I pump  I 0 cos 2 
  ETHz
Time
7
Effect of optical bias
Background
I p [1  cos  r ]
Raw data
I p [1  cos( r   )]
Background subtracted
I p [cos  r  cos( r   )]
 I p (2 r   2 ).
 The signal can be linear or nonlinear depends on the relative magnitude
of r and .
 The signal can flip sign artificially!
8
Intensity distortion
1.5
B
0.67
0.59
0.50
0.33
0.18
0.07
0
A
0.5
cos  r  cos( r   )
 2 r   2 ,
0.0
5
6
7
8
t (ps)
1.0
1.0
B
A
0.8
0.8
0.6
0.6
Signal
Signal
I (a.u.)
1.0
0.4
0.4
0.2
0.2
0.0
0.0
-0.2
-0.0
-0.2
-0.4
-0.6
-0.8
THz field strength (au)
-1.0
0.0
0.2
0.4
0.6
0.8
1.0
THz field strength (au)
9
Correction and caution
 These distortion are important for near zero optical (crossed polarizer)
configuration.
– Recent SLAC and FELIX experiments are performed in this region
 In general, correction is impossible if signal sign flipping occurs, i.e., the
beam induced phase shift becomes larger than the residue/bias and has an
opposite sign.
– [Jiang et al., APL 74, 1191 (1999)]
 To avoid artificial sign flipping and distortion
– Working with large optical bias up to quarter wave to maintain linearity
(balanced detector)
– If have to work at near to zero bias, proper orientation of the sampling
crystal is needed to make the residue in line with the expected field
orientation.
10
Dependence on sampling crystal orientation: unexpected
Planken eta l., JOSA B18, 313 (2001)
0.8
I (a.u.)
0.4
0.0
-0.4
-0.8
0
50
100
150
200
250
300
350
Orientation (degree)
11
Experimental waveform at different angles
Waveform at angles are completely different
1.0
I (a.u.)
40
220
0.0
0.5
85
265
-0.5
0.0
I (a.u.)
1.0 -2
0
2
4
-1.0
6 1.0-2
135
315
0.5
0
2
4
6
165
345
0.5
0.0
0.0
-0.5
-2
0
2
t (ps)
4
6
-2
0
2
t (ps)
4
6
•First observation of orientation
dependence in this geometry
•May have to do with the tilt of
the crystal?
•Further investigation is needed
12
SR applications
beam profile and position monitor in 1
 Linac: obvious
– SASE, etc
 Storage ring: turn by turn profile monitor
– Short bunch/CSR instability/CSR radiation (Kuske, Byrd)
– Femto slicing (Byrd, Baeck)
– Tilted beam (K. Harkay, Borland)
– Microwave instability/bursting mode
– Charge fluctuation
– Bunch length modulation (Biscari)
– Timing monitor for pump probe experiment
13
SR application example 1
 Microwave instability
I
I
1.05
1
t
-30
-20
-10
10
20
ps
30
0.95
0.8
0.9
0.85
0.6
0.8
0.4
0.2
-150
-100
-50
50
100
150
t
ps
40 ps rms bunch + modulation (3 ps, 2%)
E beam:
12 nC
Laser:
2% bandwidth @ 800 nm, stretched to 60 ps rms
Crystal:
0.1 mm ZnTe @ 1 cm from the beam
A 0.015% white noise is added to simulate the noise level of a 16 bit detector.
14
SR application 2: Timing monitor for pump-probe
experiment
 Locking the laser to the pump/probe laser
 Observe the relative shift of the bunch in respect to the laser pulse
Bunch oscillation in bucket by 10 ps
I
0.06
0.05
0.04
0.03
0.02
0.01
t
-150
-100
-50
50
100
ps
150
E beam:
40 ps, 12 nC
Laser:
2% BW @ 800 nm, 100 ps
Crystal:
0.1 mm ZnTe @ 1 cm
0.015% white noise added to simulate a realistic situation for a 16 bit camera.
15
Summary
 Distortion at near zero optical bias
– Artificial flipping of field sign
– Quadratic signal dependence on the field under investigation
– Dependence on the orientation of the sampling crystal
 Application in SR
– As beam profile monitor/transverse motion monitor
– As timing monitor for pump-probe experiment
– ….
 Future work needed:
– Clarify the angular dependence of the crystal orientation
– Crystal property measurement: to reach the limit of the technique
16