FEL2011 - List of Authors (Taira, Y.)

Paper

Title

Page

Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II

212

T. Tanikawa
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
M. Adachi, M. Katoh, J. Yamazaki, H. Zen
UVSOR, Okazaki, Japan
M. Hosaka, Y. Taira, N. Yamamoto
Nagoya University, Nagoya, Japan

Light source by using a laser seeding technique are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region, and also in generating CH with variable polarizations in deep UV [1]. In previous conferences, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependencies, and injection laser power dependencies on VUV CHs [2]. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena, which are the necessary power of injection laser to achieve the saturation of CHG is different in different harmonic orders, and the CH intensity is oscillated in deep saturated regime. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations.
[1] M. Labat, et al., Phys. Rev. Lett. 101 (2008) 164803
[2] T. Tanikawa, et al., Prc. 1st Int. Particle Accelerator Conf., Kyoto, 2010.
[3] T. Tanikawa, et al., Appl. Phys. Express 3 (2010) 122702

WEOC4

Intense Coherent THz Synchrotron Radiation Induced by a Storage Ring FEL Seeded with a Femtosecond Laser

M. Hosaka, Y. Taira, Y. Takashima, N. Yamamoto
Nagoya University, Nagoya, Japan
M. Adachi, M. Katoh, T. Tanikawa, H. Zen
UVSOR, Okazaki, Japan
S. Bielawski, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
C. Evain
SOLEIL, Gif-sur-Yvette, France

Very recently, we have succeeded in seeding a resonator FEL by injecting an external femtosecond laser at the UVSOR-II storage ring [1]. Intense coherent synchrotron radiation (CSR) in the THz region from a bending magnet was observed when the seeded FEL was operated in the pulsed Q-switch mode [2]. We have also found that the CSR intensity depends on the pulse duration of the seed laser. The CSR intensity is enhanced with short pulse ~200 fsec and suppressed with longer pulse ~200 psec. Simultaneous measurement of the terahertz radiation and the FEL pulse reveals that the radiation is emitted in the growing phase of the Q-switch FEL pulse. We think that the CSR comes from repetitive interactions between the laser pulse and the electron bunch as the short pulse laser growth in the optical cavity. In the presentation, we will also discuss the production mechanism of the CSR.
[1] C. Szwaj et al., FEL2011, TUPB05, in this conference.
[2] H. Zen et al., FEL2011, TUPA13, in this conference.

Slides WEOC4 [2.715 MB]

Paper	Title	Page
TUPA11	Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II	212
	T. Tanikawa PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France M. Adachi, M. Katoh, J. Yamazaki, H. Zen UVSOR, Okazaki, Japan M. Hosaka, Y. Taira, N. Yamamoto Nagoya University, Nagoya, Japan
	Light source by using a laser seeding technique are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region, and also in generating CH with variable polarizations in deep UV [1]. In previous conferences, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependencies, and injection laser power dependencies on VUV CHs [2]. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena, which are the necessary power of injection laser to achieve the saturation of CHG is different in different harmonic orders, and the CH intensity is oscillated in deep saturated regime. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations. [1] M. Labat, et al., Phys. Rev. Lett. 101 (2008) 164803 [2] T. Tanikawa, et al., Prc. 1st Int. Particle Accelerator Conf., Kyoto, 2010. [3] T. Tanikawa, et al., Appl. Phys. Express 3 (2010) 122702

WEOC4	Intense Coherent THz Synchrotron Radiation Induced by a Storage Ring FEL Seeded with a Femtosecond Laser
	M. Hosaka, Y. Taira, Y. Takashima, N. Yamamoto Nagoya University, Nagoya, Japan M. Adachi, M. Katoh, T. Tanikawa, H. Zen UVSOR, Okazaki, Japan S. Bielawski, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France C. Evain SOLEIL, Gif-sur-Yvette, France
	Very recently, we have succeeded in seeding a resonator FEL by injecting an external femtosecond laser at the UVSOR-II storage ring [1]. Intense coherent synchrotron radiation (CSR) in the THz region from a bending magnet was observed when the seeded FEL was operated in the pulsed Q-switch mode [2]. We have also found that the CSR intensity depends on the pulse duration of the seed laser. The CSR intensity is enhanced with short pulse ~200 fsec and suppressed with longer pulse ~200 psec. Simultaneous measurement of the terahertz radiation and the FEL pulse reveals that the radiation is emitted in the growing phase of the Q-switch FEL pulse. We think that the CSR comes from repetitive interactions between the laser pulse and the electron bunch as the short pulse laser growth in the optical cavity. In the presentation, we will also discuss the production mechanism of the CSR. [1] C. Szwaj et al., FEL2011, TUPB05, in this conference. [2] H. Zen et al., FEL2011, TUPA13, in this conference.
	Slides WEOC4 [2.715 MB]