FEL2011 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
MOPA02	Development of a Microscopic Irradiation Technique for Delivering VIS-FELs to Single Cells through a Fine-tapered Glass Rod	FEL, laser, electron, controls	16
	F. Shishikura Nihon University School of Medicine, Tokyo, Japan K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka LEBRA, Funabashi, Japan
	The first lasing of LEBRA* succeeded in 2001 to produce near infrared FELs, by which the higher harmonics generated by means of the non-linear optical crystals now covered with visible and near infrared regions from 0.35 to 6 microns. The VIS-FELs are of particular interest and are expected to reveal photochemical reactions of single cells, even those in living organisms. To do this, it is a prerequisite to develop a micro-irradiation technique for targeting a single cell without photochemical effect to neighboring cells. We have established a microscopic irradiation technique with VIS-FELs through a fine glass rod. The FEL delivered through a fine-tapered glass rod with a diameter of about 5 microns has two major advantages compared with conventional microscope irradiation systems. The first is to deliver the FEL directly into targeted single cells in accordance with standard microinjection techniques used in developmental biology. The second is the ability to irradiate specific areas of the cytoplasm including cell organelle without severely damaging targeted cells. Using this technique, we also report micro-irradiation experiments on targeted single cells in living organisms. *Laboratory for Electron Beam Research and Application, Nihon University

MOPB05	Smith-Purcell Radiation with Negative-index Material	radiation, electron, laser, feedback	20
	D. Li, K. Imasaki ILT, Suita, Osaka, Japan M.R. Asakawa Kansai University, Osaka, Japan M. Hangyo, K. Takano ILE Osaka, Suita, Japan S. Miyamoto LASTI, Hyogo, Japan Y. Tsunawaki OSU, Daito, Osaka, Japan Z. Yang UESTC, Chengdu, Sichuan, People's Republic of China
	Smith-Purcell radiation from an electric line charge that moves, at constant speed, parallel to a grating made of metamaterial with negative index is analyzed. Through theoretical analysis and computations, we show that the Smith-Purcell radiation is stronger from a grating of negative-index material, than positive-index material and perfect conductor. Also, we found the radiation strongly depends on the values of permeability and permittivity.

MOPB06	Smith-Purcell Free Electron Laser with Bragg Reflector	electron, laser, simulation, radiation	24
	D. Li, K. Imasaki ILT, Suita, Osaka, Japan M.R. Asakawa Kansai University, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan S. Miyamoto LASTI, Hyogo, Japan Y. Tsunawaki OSU, Daito, Osaka, Japan Z. Yang UESTC, Chengdu, Sichuan, People's Republic of China
	Grating with Bragg reflectors for the Smith-Purcell free-electron laser is proposed to improve the reflection coefficient, resulting in enhancing the interaction of the surface wave with the electron beam and, consequently, relax the requirements to the electron beam. With the help of particle-in-cell simulations, it has been shown that, the usage of Bragg reflectors may improve the growth rate, shorten the time for the device to reach saturation and lower the start current for the operation of a Smith-Purcell free-electron laser.

MOPC21	Comparison of Growth Rates of Two-Stream Free Electron Lasers (TSFEL) with Planar Wiggler Magnet and AC Electrical Wiggler Pumps	wiggler, electron, FEL, laser	136
	N. Mahdizadeh Islamic Azad University, Sabzevar Branch, Sabzevar, Iran F.M. Aghamir University of Tehran, Tehran, Iran
	Funding: Sabzevar Branch, Islamic Azad University A Comparison between growth rates of a Two Stream Free Electron Laser (TSFEL) with a planar wiggler pump and ac electrical wiggler pump has been presented. With the aid of fluid theory, dispersion relations are derived and their characteristics have been numerically analyzed. In this analysis, the longitudinal component of the stress tensor has been retained for beam temperature consideration. Similarities and differences in dispersion relations and growth rate have, also, been presented.

MOPC22	Nonlinear Analyses in Two-stream Free-Electron Laser with Helical Wiggler Pump	electron, wiggler, radiation, FEL	138
	N. Mahdizadeh Islamic Azad University, Sabzevar Branch, Sabzevar, Iran F.M. Aghamir University of Tehran, Tehran, Iran A. Raghavi PNUM, Mashhad, Iran
	Funding: Sabzevar Branch, Islamic Azad University The analysis of a Two-Stream Free Electron Laser (TSFEL) with a helical wiggler pump is presented. The power and the signal growth rate are calculated. A set of coupled nonlinear differential equations for slowly varying amplitudes and phases is obtained through the substitution of vector and scalar potentials into the Maxwell-Poisson equations. The electron orbit equations are derived by Lorentz force equation. The obtained equations for fields and ensemble of electrons are solved numerically. The power and growth rate of TSFEL are compared with those of conventional FEL. It has been found that the TSFEL reaches the saturation regime in a longer axial distance in comparison to the conventional FEL and the growth rate of the TSFEL is somewhat lower than conventional FEL.

MOPC27	Small Signal Gain for Two Stream FEL	electron, FEL, wiggler, resonance	141
	A. Raghavi PNUM, Mashhad, Iran N. Mahdizadeh Islamic Azad University, Sabzevar Branch, Sabzevar, Iran
	The problem of wave-particle interaction in the small signal gain regime for the tow-stream free electron laser is considered using a relativistic moving frame. The equation of motion in this frame is solved by means of a non-relativistic Hamiltonian. Small signal gain (SSG) for the laser is derived in both moving and laboratory frames.

TUOA2	Collective and Individual Aspects of Fluctuations in Relativistic Electron Beams for Free Electron Lasers	plasma, electron, FEL, bunching	156
	K.-J. Kim, R.R. Lindberg ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Fluctuations in highly bright, relativistic electron beam for free electron lasers (FELs) exhibit both collective as well as individual particle aspects[1]. If the collective part characterized by plasma oscillation dominate, then it might be feasible to suppress the shot noise[2]. To study these issues, we solve the 1-D coupled Poisson-Klimontovich equations by the Laplace transform technique. We find the density fluctuations to be a linear combination of the collective plasma oscillation and the random motion of Debye-screened dressed particles[3]. The relative magnitude ξ of the random to the collective part can be computed explicitly. For the LCLS case, we find that ξ is about unity for electron beams just prior to the λ = 1.5 Å FEL, and about 1% for the beam at 135 MeV at λ = 1 μm. The “position noise” (bunching factor) could be reduced to about ξ by a quarter of plasma oscillation. However, this leads to an increase in the “momentum noise”, which contributes significantly to the growth of the self-amplified spontaneous emission. [1] D. Pines, D. Bohm, Phys. Rev.,85,338 (1952) [2] A. Gover, E. Dyunin, Phys. Rev.Letters, 102,154801 (2009) [3] S. Ichimaru, Basic Principles of Plasma Physics, The Benjamin/Cummins Pub. Co. (1973)
	Slides TUOA2 [0.361 MB]

TUPB09	Free Electron Lasers in 2011	FEL, electron, undulator, laser	274
	J. Blau, K. R. Cohn, W.B. Colson, C.M. Pogue, M. Stanton, A.I. Yilmaz NPS, Monterey, California, USA
	Funding: This work has been supported by the Office of Naval Research. Thirty-five years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.

WEPA14	Effect of a Quasiperiodic Undulator on FEL Radiation	undulator, radiation, electron, FEL	352
	F. Briquez, C. Benabderrahmane, M.-E. Couprie, C. Evain, M. Labat SOLEIL, Gif-sur-Yvette, France
	The operation of conventional undulators results from an interference scheme in order to generate radiation of a fundamental wavelength and its harmonics. Whereas these harmonics are in most of the cases useful to reach higher energies, it is profitable in specific configurations to shift or reduce them, for instance to limit power on optics or to distinguish between one or two photon process in user experiments. This can be performed by so-called quasi-periodic undulators in which the periodicity of the magnetic field is destructed. In this case, the field amplitude is reduced on a few positions among the axis, inducing a destruction of the interference scheme. Such undulators are commonly used to generate spontaneous emission in synchrotron radiation facilities but could also be installed in Free Electron Lasers. The emitted radiation of the quasi-periodic undulator is compared with the usual configuration one, in the case of LUNEX5. Simulations using GENESIS code are described and results are discussed.

WEPA19	Report on the Redesign of the Fibre Link Stabilisation Units at FLASH	laser, optics, controls, alignment	370
	M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, H. Schlarb, B. Schmidt, S. Schulz DESY, Hamburg, Germany M. Kuntzsch HZDR, Dresden, Germany
	Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285) Recently, the fibre link stabilisation unit of the optical synchronisation system at FLASH has been subject to several design changes involving some major issues. Enhancements of the optical design have led to improvements in the efficiency of the free space optics and a new optical delay line allows for a more than two times longer adjustment range. The amplitude noise, encountered previously at the remote station of the links, was drastically decreased by a new beam splitting configuration. In future, this new link design will not only be used for the planned additional fibre links at FLASH, but it will also replace the already installed ones. In this paper we report on the changes of opto-mechanical design and we present first results from the recently commissioned links.

WEPA24	Error Analysis for Hybrid Undulators	undulator, insertion, insertion-device, laser	387
	D. Arbelaez, A. Madur, S. Marks, S. Prestemon, D. Schlueter LBNL, Berkeley, California, USA H.-D. Nuhn SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Director, Office of Science, of the US Department of Energy under Contract No. DE-AC02-05CH11231. An analysis is performed on various possible errors that may occur throughout a hybrid undulator. Of particular significance is the scaling of the various errors with variations in the gap of the device. Tuning strategies are considered for the mitigation of these errors for the entire range of usable gap. Sorting strategies for the reduction of the initial errors in the undulator are also considered. Specifically, the effectiveness of the sorting algorithm is evaluated with respect to the number of permanent magnet blocks used per pole as well as the size and distribution of the block population. The results of this analysis are applied to the LCLS-II undulators to determine the required machining and positioning tolerances and viable tuning strategies in order to meet the design requirements.

THPA32	Femtosecond Stable Laser-to-RF Phase Detection Using Optical Modulators	laser, controls, coupling, feedback	551
	T. Lamb, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz DESY, Hamburg, Germany E. Janas Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Free-Electron Lasers like FLASH and the European XFEL require the synchronization of RF stations to the optical timing reference of the accelerator. For this purpose, a new technique to phase-lock RF sources to an optical pulse train has been invented. The new technique uses an opto-microwave coupling device together with an ultra-low phase-noise RF source operating at a frequency of 1.3 GHz. In our arrangement, the laser-to-RF phase detector is insensitive to amplitude fluctuations of the optical reference pulse train, which allows the detector to achieve femtosecond precision over long time periods. In this paper, we present the balanced laser-to-RF phase detection principle along with a tolerance study of the arrangement and first results from our prototype setup.

FROA3	Sub-100-attosecond Timing Jitter Ultrafast Fiber Lasers for FEL Optical Master Oscillators	laser, FEL, cavity, electron	648
	J. Kim, K. Jung, C. Kim, H. Kim, T.K. Kim, S. Park, Y. Song, H. Yang KAIST, Daejeon, Republic of Korea
	Funding: Pohang Accelerator Laboratory and NRF of Korea (2010-0003974) Future FELs require femtosecond and even sub-femtosecond timing precision over the entire facility. To meet this timing demand, optical techniques based on modulated cw lasers or ultrafast pulsed lasers have been investigated intensively. It has recently been shown that the timing system based on ultrafast fiber lasers and timing-stabilized fiber links enables long-term stable, sub-10-femtosecond level synchronization []. In order to achieve sub-femtosecond level synchronization, the optimization of timing jitter in ultrafast fiber lasers is required. In this work, by operating the fiber lasers at close-to-zero intracavity dispersion, we optimize the timing jitter of ultrafast fiber lasers toward sub-femtosecond level for the first time. The measured timing jitter of 80 MHz Er-fiber and Yb-fiber lasers is 100 attosecond and 185 attosecond, respectively, when integrated from 10 kHz to 40 MHz (Nyquist frequency) offset frequency. To our knowledge, this is the lowest high-frequency timing jitter from ultrafast fiber lasers so far. The sub-100-attosecond timing jitter from optical master oscillators is the first step toward attosecond-precision FEL timing systems. [1] J. Kim et al, "Drift-free femtosecond timing synchronization of remote optical and microwave sources," Nature Photonics 2, 733-736 (2008).*

Paper

Title

Other Keywords

Page

Development of a Microscopic Irradiation Technique for Delivering VIS-FELs to Single Cells through a Fine-tapered Glass Rod

FEL, laser, electron, controls

16

F. Shishikura
Nihon University School of Medicine, Tokyo, Japan
K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Tanaka
LEBRA, Funabashi, Japan

The first lasing of LEBRA* succeeded in 2001 to produce near infrared FELs, by which the higher harmonics generated by means of the non-linear optical crystals now covered with visible and near infrared regions from 0.35 to 6 microns. The VIS-FELs are of particular interest and are expected to reveal photochemical reactions of single cells, even those in living organisms. To do this, it is a prerequisite to develop a micro-irradiation technique for targeting a single cell without photochemical effect to neighboring cells. We have established a microscopic irradiation technique with VIS-FELs through a fine glass rod. The FEL delivered through a fine-tapered glass rod with a diameter of about 5 microns has two major advantages compared with conventional microscope irradiation systems. The first is to deliver the FEL directly into targeted single cells in accordance with standard microinjection techniques used in developmental biology. The second is the ability to irradiate specific areas of the cytoplasm including cell organelle without severely damaging targeted cells. Using this technique, we also report micro-irradiation experiments on targeted single cells in living organisms.
*Laboratory for Electron Beam Research and Application, Nihon University

MOPB05

Smith-Purcell Radiation with Negative-index Material

radiation, electron, laser, feedback

20

D. Li, K. Imasaki
ILT, Suita, Osaka, Japan
M.R. Asakawa
Kansai University, Osaka, Japan
M. Hangyo, K. Takano
ILE Osaka, Suita, Japan
S. Miyamoto
LASTI, Hyogo, Japan
Y. Tsunawaki
OSU, Daito, Osaka, Japan
Z. Yang
UESTC, Chengdu, Sichuan, People's Republic of China

Smith-Purcell radiation from an electric line charge that moves, at constant speed, parallel to a grating made of metamaterial with negative index is analyzed. Through theoretical analysis and computations, we show that the Smith-Purcell radiation is stronger from a grating of negative-index material, than positive-index material and perfect conductor. Also, we found the radiation strongly depends on the values of permeability and permittivity.

MOPB06

Smith-Purcell Free Electron Laser with Bragg Reflector

electron, laser, simulation, radiation

24

D. Li, K. Imasaki
ILT, Suita, Osaka, Japan
M.R. Asakawa
Kansai University, Osaka, Japan
M. Hangyo
ILE Osaka, Suita, Japan
S. Miyamoto
LASTI, Hyogo, Japan
Y. Tsunawaki
OSU, Daito, Osaka, Japan
Z. Yang
UESTC, Chengdu, Sichuan, People's Republic of China

Grating with Bragg reflectors for the Smith-Purcell free-electron laser is proposed to improve the reflection coefficient, resulting in enhancing the interaction of the surface wave with the electron beam and, consequently, relax the requirements to the electron beam. With the help of particle-in-cell simulations, it has been shown that, the usage of Bragg reflectors may improve the growth rate, shorten the time for the device to reach saturation and lower the start current for the operation of a Smith-Purcell free-electron laser.

MOPC21

Comparison of Growth Rates of Two-Stream Free Electron Lasers (TSFEL) with Planar Wiggler Magnet and AC Electrical Wiggler Pumps

wiggler, electron, FEL, laser

136

N. Mahdizadeh
Islamic Azad University, Sabzevar Branch, Sabzevar, Iran
F.M. Aghamir
University of Tehran, Tehran, Iran

Funding: Sabzevar Branch, Islamic Azad University
A Comparison between growth rates of a Two Stream Free Electron Laser (TSFEL) with a planar wiggler pump and ac electrical wiggler pump has been presented. With the aid of fluid theory, dispersion relations are derived and their characteristics have been numerically analyzed. In this analysis, the longitudinal component of the stress tensor has been retained for beam temperature consideration. Similarities and differences in dispersion relations and growth rate have, also, been presented.

MOPC22

Nonlinear Analyses in Two-stream Free-Electron Laser with Helical Wiggler Pump

electron, wiggler, radiation, FEL

138

N. Mahdizadeh
Islamic Azad University, Sabzevar Branch, Sabzevar, Iran
F.M. Aghamir
University of Tehran, Tehran, Iran
A. Raghavi
PNUM, Mashhad, Iran

Funding: Sabzevar Branch, Islamic Azad University
The analysis of a Two-Stream Free Electron Laser (TSFEL) with a helical wiggler pump is presented. The power and the signal growth rate are calculated. A set of coupled nonlinear differential equations for slowly varying amplitudes and phases is obtained through the substitution of vector and scalar potentials into the Maxwell-Poisson equations. The electron orbit equations are derived by Lorentz force equation. The obtained equations for fields and ensemble of electrons are solved numerically. The power and growth rate of TSFEL are compared with those of conventional FEL. It has been found that the TSFEL reaches the saturation regime in a longer axial distance in comparison to the conventional FEL and the growth rate of the TSFEL is somewhat lower than conventional FEL.

MOPC27

Small Signal Gain for Two Stream FEL

electron, FEL, wiggler, resonance

141

A. Raghavi
PNUM, Mashhad, Iran
N. Mahdizadeh
Islamic Azad University, Sabzevar Branch, Sabzevar, Iran

The problem of wave-particle interaction in the small signal gain regime for the tow-stream free electron laser is considered using a relativistic moving frame. The equation of motion in this frame is solved by means of a non-relativistic Hamiltonian. Small signal gain (SSG) for the laser is derived in both moving and laboratory frames.

TUOA2

Collective and Individual Aspects of Fluctuations in Relativistic Electron Beams for Free Electron Lasers

plasma, electron, FEL, bunching

156

K.-J. Kim, R.R. Lindberg
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Fluctuations in highly bright, relativistic electron beam for free electron lasers (FELs) exhibit both collective as well as individual particle aspects[1]. If the collective part characterized by plasma oscillation dominate, then it might be feasible to suppress the shot noise[2]. To study these issues, we solve the 1-D coupled Poisson-Klimontovich equations by the Laplace transform technique. We find the density fluctuations to be a linear combination of the collective plasma oscillation and the random motion of Debye-screened dressed particles[3]. The relative magnitude ξ of the random to the collective part can be computed explicitly. For the LCLS case, we find that ξ is about unity for electron beams just prior to the λ = 1.5 Å FEL, and about 1% for the beam at 135 MeV at λ = 1 μm. The “position noise” (bunching factor) could be reduced to about ξ by a quarter of plasma oscillation. However, this leads to an increase in the “momentum noise”, which contributes significantly to the growth of the self-amplified spontaneous emission.
[1] D. Pines, D. Bohm, Phys. Rev.,85,338 (1952)
[2] A. Gover, E. Dyunin, Phys. Rev.Letters, 102,154801 (2009)
[3] S. Ichimaru, Basic Principles of Plasma Physics, The Benjamin/Cummins Pub. Co. (1973)

Slides TUOA2 [0.361 MB]

TUPB09

Free Electron Lasers in 2011

FEL, electron, undulator, laser

274

J. Blau, K. R. Cohn, W.B. Colson, C.M. Pogue, M. Stanton, A.I. Yilmaz
NPS, Monterey, California, USA

Funding: This work has been supported by the Office of Naval Research.
Thirty-five years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.

WEPA14

Effect of a Quasiperiodic Undulator on FEL Radiation

undulator, radiation, electron, FEL

352

F. Briquez, C. Benabderrahmane, M.-E. Couprie, C. Evain, M. Labat
SOLEIL, Gif-sur-Yvette, France

The operation of conventional undulators results from an interference scheme in order to generate radiation of a fundamental wavelength and its harmonics. Whereas these harmonics are in most of the cases useful to reach higher energies, it is profitable in specific configurations to shift or reduce them, for instance to limit power on optics or to distinguish between one or two photon process in user experiments. This can be performed by so-called quasi-periodic undulators in which the periodicity of the magnetic field is destructed. In this case, the field amplitude is reduced on a few positions among the axis, inducing a destruction of the interference scheme. Such undulators are commonly used to generate spontaneous emission in synchrotron radiation facilities but could also be installed in Free Electron Lasers. The emitted radiation of the quasi-periodic undulator is compared with the usual configuration one, in the case of LUNEX5. Simulations using GENESIS code are described and results are discussed.

WEPA19

Report on the Redesign of the Fibre Link Stabilisation Units at FLASH

laser, optics, controls, alignment

370

M.K. Bock, M. Bousonville, M. Felber, P. Gessler, T. Lamb, H. Schlarb, B. Schmidt, S. Schulz
DESY, Hamburg, Germany
M. Kuntzsch
HZDR, Dresden, Germany

Funding: This work is partly supported by IRUVX-PP an EU co-funded project under FP7 (Grant Agreement 211285)
Recently, the fibre link stabilisation unit of the optical synchronisation system at FLASH has been subject to several design changes involving some major issues. Enhancements of the optical design have led to improvements in the efficiency of the free space optics and a new optical delay line allows for a more than two times longer adjustment range. The amplitude noise, encountered previously at the remote station of the links, was drastically decreased by a new beam splitting configuration. In future, this new link design will not only be used for the planned additional fibre links at FLASH, but it will also replace the already installed ones. In this paper we report on the changes of opto-mechanical design and we present first results from the recently commissioned links.

WEPA24

Error Analysis for Hybrid Undulators

undulator, insertion, insertion-device, laser

387

D. Arbelaez, A. Madur, S. Marks, S. Prestemon, D. Schlueter
LBNL, Berkeley, California, USA
H.-D. Nuhn
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Director, Office of Science, of the US Department of Energy under Contract No. DE-AC02-05CH11231.
An analysis is performed on various possible errors that may occur throughout a hybrid undulator. Of particular significance is the scaling of the various errors with variations in the gap of the device. Tuning strategies are considered for the mitigation of these errors for the entire range of usable gap. Sorting strategies for the reduction of the initial errors in the undulator are also considered. Specifically, the effectiveness of the sorting algorithm is evaluated with respect to the number of permanent magnet blocks used per pole as well as the size and distribution of the block population. The results of this analysis are applied to the LCLS-II undulators to determine the required machining and positioning tolerances and viable tuning strategies in order to meet the design requirements.

THPA32

Femtosecond Stable Laser-to-RF Phase Detection Using Optical Modulators

laser, controls, coupling, feedback

551

T. Lamb, M.K. Bock, M. Bousonville, M. Felber, P. Gessler, F. Ludwig, S. Ruzin, H. Schlarb, B. Schmidt, S. Schulz
DESY, Hamburg, Germany
E. Janas
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Free-Electron Lasers like FLASH and the European XFEL require the synchronization of RF stations to the optical timing reference of the accelerator. For this purpose, a new technique to phase-lock RF sources to an optical pulse train has been invented. The new technique uses an opto-microwave coupling device together with an ultra-low phase-noise RF source operating at a frequency of 1.3 GHz. In our arrangement, the laser-to-RF phase detector is insensitive to amplitude fluctuations of the optical reference pulse train, which allows the detector to achieve femtosecond precision over long time periods. In this paper, we present the balanced laser-to-RF phase detection principle along with a tolerance study of the arrangement and first results from our prototype setup.

FROA3

Sub-100-attosecond Timing Jitter Ultrafast Fiber Lasers for FEL Optical Master Oscillators

laser, FEL, cavity, electron

648

J. Kim, K. Jung, C. Kim, H. Kim, T.K. Kim, S. Park, Y. Song, H. Yang
KAIST, Daejeon, Republic of Korea

Funding: Pohang Accelerator Laboratory and NRF of Korea (2010-0003974)
Future FELs require femtosecond and even sub-femtosecond timing precision over the entire facility. To meet this timing demand, optical techniques based on modulated cw lasers or ultrafast pulsed lasers have been investigated intensively. It has recently been shown that the timing system based on ultrafast fiber lasers and timing-stabilized fiber links enables long-term stable, sub-10-femtosecond level synchronization [*]. In order to achieve sub-femtosecond level synchronization, the optimization of timing jitter in ultrafast fiber lasers is required. In this work, by operating the fiber lasers at close-to-zero intracavity dispersion, we optimize the timing jitter of ultrafast fiber lasers toward sub-femtosecond level for the first time. The measured timing jitter of 80 MHz Er-fiber and Yb-fiber lasers is 100 attosecond and 185 attosecond, respectively, when integrated from 10 kHz to 40 MHz (Nyquist frequency) offset frequency. To our knowledge, this is the lowest high-frequency timing jitter from ultrafast fiber lasers so far. The sub-100-attosecond timing jitter from optical master oscillators is the first step toward attosecond-precision FEL timing systems.
[1] J. Kim et al, "Drift-free femtosecond timing synchronization of remote optical and microwave sources," Nature Photonics 2, 733-736 (2008).