3D Laser pulse shaping for photoinjector applications Yuelin Li Accelerator Systems Division and X-ray Science Division Argonne National Laboratory

ERL 2009, Ithaca, June 9, Acknowledgement K. Harkay, K.-J. Kim, and E. Gluskin for strong support J. Lewellen, Y. Sun for discussion and help with GPT simulation S. Chemrisov for helping with experiments This work is support by DOE, Office of Basic Science

ERL 2009, Ithaca, June 9, Outline The case of pulse shaping: high brightness or low emittance –Thermal/cathode emittance: casted after emission –Emittance growth due to space charge force: can be compensated –Uniform ellipsoidal beam is the key Pulse shaping techniques –Mechanical: pulse stacking –Physics: self evolving –Phase modulation: Mechanism optics and beam simulation Progress at ANL: A proof of principle experiment –Measurement method –Phase tailoring procedure –Results Summary

ERL 2009, Ithaca, June 9, Outline The case of pulse shaping: high brightness or low emittance –Thermal/cathode emittance: casted after emission –Emittance growth due to space charge force: can be compensated –Uniform ellipsoidal beam is the key Pulse shaping techniques –Mechanical: pulse stacking –Physics: self evolving –Phase modulation: Mechanism optics and beam simulation Progress at ANL: A proof of principle experiment –Measurement method –Phase tailoring procedure –Results Summary and acknowledgement

ERL 2009, Ithaca, June 9, The case of pulse shaping The case of pulse shaping: –Theory of emittance compensation Emittance growth due to space charge force can be compensated if the space charge force is linear – Carlsten, NIMA 285, 313, (1989) – Serafini and Rosenzweig, PRE 55, 7565 (1997) –Homogeneous ellipsoidal beam is the key Uniform electron density distribution in a ellipsoid Has linear space charge force (M. Reiser, Theory and Design of Charged Particle Beams, Wiley, New York.) {

ERL 2009, Ithaca, June 9, Space charge force distribution: three geometries 3D Gaussian Cylindrical H. Ellipsodial

ERL 2009, Ithaca, June 9, Outline The case of pulse shaping: high brightness or low emittance –Thermal/cathode emittance: casted after emission –Emittance growth due to space charge force: can be compensated –Uniform ellipsoidal beam is the key Pulse shaping techniques –Mechanical: pulse stacking –Physics: self evolving –Phase modulation: Mechanism optics and beam simulation Progress at ANL: A proof of principle experiment –Measurement method –Phase tailoring procedure –Results Summary

ERL 2009, Ithaca, June 9, Pulse stacking Excellent for longitudinally flat topped pulse –Interferometer setup C. Sider, Appl. Opt. 37, 5302 (1998). –Bi-fringence crystals C. S. Zhou, et al., Applied Optics 46, (2007). I.V. Bazarov, D.G. Ouzounov, B.M. Dunham, Phys. Rev. ST AB 11, (2008). For uniform ellipsoidal pulse generation: very complicated –First beam simulation by Limborg C. Limborg-Deprey and P. Bolton, Nucl. Instrum. Methods A 557, 106 (2006). –Design exists, but with low efficiency H. Tomizawa, private communication).

ERL 2009, Ithaca, June 9, Self-evolution of the a pancake beam Pro –Easy: Need a short pulse (100 fs) with initial parabolic transverse distribution, no longi shaping needed Con –Cannot put too many charges: image charge will distort the beam –Pancake geometry thus larger transverse size: larger cathode emittance to start with L. Serafini, AIP Conf. Proc. 413, 321 (1997). O. J. Luiten et al, Phys. Rev. Lett. 93, (2004). B. J. Claessens, Phys. Rev. Lett. 95, (2005). J. B. Rosenzweig et al., Nucl. Instrum. Methods A 557, 87 (2006). P. Musumeci, et al., Phys. Rev. Lett. 100, (2008).

ERL 2009, Ithaca, June 9, Pulse shaping: 3D laser pulse shaping to generate an ellipsoidal beam Difficulties –Simultaneous evolving longitudinal and transverse profiles –Homogeneous in 3-D –Actually a 2-D problem due to rotation symmetry Hope: coupling between time and space via chromatic dispersion Phase:  (  ) Amplitude: A(  ) Frequency domain Phase:  (t) Amplitude: A(t) Size: r(t) Amplitude: A(t) Chromatic dispersion Time domain Spatiotemporal =

ERL 2009, Ithaca, June 9, Phase tailoring t  Chromatic dispersion for ellipsoidal pulse Chromatic dispersion + Radius modulation

ERL 2009, Ithaca, June 9, Can an ellipsoidal pulse be generated? Y. Li and J. Lewellen, PRL 100, (2008) A EM pulse can be written as An ellipsoidal pulse Chromatic Dispersion Gaussian beam Therefore

ERL 2009, Ithaca, June 9, Numerical calculation: Fourier optics method Full wave optics (Fresnel diffraction) adapted from Kempe et al. (JOSA B 9, 1158 (1992)) Group velocity dispersion and group velocity delay effect considered up to the second order Kempe et al.,JOSA B 9, 1158 (1992)

ERL 2009, Ithaca, June 9, The 3D laser pulse at the focal plane of a lens f=150 mm, 249 nm, 12 ps FW Li, Lewellen and Chemerisov, PRSTAB 12, (2009).  =8%, 4%, 2%, 1%, and 0.5%, a0=25 mm, a 0 =25, 12, 6, 4, and 2 mm,  =8%,

ERL 2009, Ithaca, June 9, Performance at 1 nC very promising in simulation Y. Li and J. Lewellen, PRL 100, (2008) Simulation condition for LCLS from: M. Ferrario et. al., Proc. EPAC 2000, p Spatiotemporal profile Emittance

ERL 2009, Ithaca, June 9, Outline The case of pulse shaping: high brightness or low emittance –Thermal/cathode emittance: casted after emission –Emittance growth due to space charge force: can be compensated –Uniform ellipsoidal beam is the key Pulse shaping techniques –Mechanical: pulse stacking –Physics: self evolving –Phase modulation: Mechanism optics and beam simulation Progress at ANL: A proof of principle experiment –Measurement method –Phase tailoring procedure –Results Summary

ERL 2009, Ithaca, June 9, A proof of principle experiment Experimental setup –800 nm laser, 1 kHz, 10 nJ per pulse, 40 nm bandwidth –ZnSe lens as the focal lens for high dispersion 25-mm diameter, 88.9-mm radius of curvature, and 2.9-mm center thickness, Janos Technology, A , Dispersion 250 fs2/mm at 800 nm ) –DAZZLER as the phase modulator –Achromatic lens for transport C AL ZSL SF PP D ODL PP: pulse picker; D: AOPDF; SF: achromatic spatial filter; ZSL: ZnSe lens; AL: achromatic image relay lens; ODL: optical delay line; C: camera. Y. Li and S. Chemerisov, Opt. Lett. 33, 1996 (2008); Li, Lewellen and Chemerisov, PRSTAB 12, (2009).

ERL 2009, Ithaca, June 9, The signal recorded on the camera is If probe is much shorter than the main pulse Measuring the contrast ratio C( ,r), and integrated probe intensity I p (r), 3D mapping method Interference term Main beam profile at  Y. Li and S. Chemerisov, Opt. Lett. 33, 1996 (2008). Li, Lewellen and Chemerisov, PRSTAB 12, (2009).

ERL 2009, Ithaca, June 9, Data processing example Raw IpIp Fringe map imim

ERL 2009, Ithaca, June 9, Phase and amplitude modulation via Acousto-optic Programmable Dispersive Filter (DAZZLER) A device widely used in laser and optical research –F. Verluise, V. Laude, Z. Cheng, Ch. Spielmann, and P. Tournois, Opt. Lett. 25, 575 (2000). DAZZLER and similar phase modulation device have been applied to photoinjector related laser pulse shaping for cylindrical pulse –H. Tomizawa et. al., Nucl. Instrum. Methods A 557, 117 (2006). –J. Yang, et al., J. Appl. Phys. 92, 1608 (2002). –S. Cialdi, et al., Appl. Opt. 46, 4959 (2007). UV version available UV version available – –T. Oksenhendler, CLEO nm

ERL 2009, Ithaca, June 9, Generating the desired phase and amplitude modulation Calculate the time domain amplitude and phase Fourier transform for frequency domain for desire spectrum Take a spectrum of the laser and calculate the spectrum to load to the DAZZLER Load the spectrum and phase to the DAZZLER Y. Li and S. Chemerisov, Opt. Lett. 33, 1996 (2008).

ERL 2009, Ithaca, June 9, Results for a Gaussian beam with different aperture size Excellent between data and simulation Work for the future –Demonstration in UV with larger beam –Beam experiment Input beam Y. Li and S. Chemerisov, Opt. Lett. 33, 1996 (2008). Li, Lewellen and Chemerisov, PRSTAB 12, (2009). Data Sim Comp

ERL 2009, Ithaca, June 9, Effect of residual linear chirp Beam radius: 1/e 2 width of 3 mm Li, Lewellen and Chemerisov, PRSTAB 12, (2009). Data Sim Comp

ERL 2009, Ithaca, June 9, Outline The case of pulse shaping: high brightness or low emittance –Thermal/cathode emittance: casted after emission –Emittance growth due to space charge force: can be compensated –Uniform ellipsoidal beam is the key Pulse shaping techniques –Mechanical: pulse stacking –Physics: self evolving –Phase modulation: Mechanism optics and beam simulation Progress at ANL: A proof of principle experiment –Measurement method –Phase tailoring procedure –Results Summary

ERL 2009, Ithaca, June 9, Summary Current status –Laser pulse shaping may generate 3D shaped pulses, potentially uniform ellipsoid –A 3D mapping method is developed Issues –High rep rate and longer pulse duration: longer crystals Fastlite, private communications Future plan –Generating a flat topped beam as input –Demonstration in UV –Beam generation