Page 125 - High Power Laser Handbook

94 G a s , C h e m i c a l , a n d F r e e - E l e c t r o n L a s e r s High-Power Fr ee-Electr on Lasers 95

Figure 4.11 An image of the Jefferson Lab’s IR Upgrade fifth through ninth
harmonics in the visible while lasing at about 3 µm.

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that it has also lased on the second, third, and fifth harmonics of the
35
fundamental wavelength. A picture of the spontaneous emission from
the harmonics is shown in Fig. 4.11. The linac also produced substantial
power in the terahertz (THz) region from collective radiation in the
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magnetic bends. A second FEL system (the UV Upgrade) on a parallel
beamline has recently lased at 150 W average power in the ultraviolet. 37
These systems have paved the way for future advances in high-
average-power FELs and in the development of energy-recovered
systems for high-brightness applications in photon research and
development. Substantial development is still required before the
FELs can reach their full potential. Perhaps in industrial applications,
but certainly at the present level of performance, an exciting set of
efforts is underway using free-electron lasers as the only real source
of truly tunable high-average-power coherent radiation in the near-
to mid-infrared region for scientific research.

References
1. Brau, C. A., Free-Electron Lasers, Academic Press, Boston, 1990.
2. Freund, H. P., and Neil, G. R., “Free Electron Generators of Microwave
Radiation,” Electron Beam Generators of Microwave Radiation Proc. IEEE, 87(5):
782–803, May 1999.
3. Feldman, D. W., Warren, R. W., Carlsten, B. E., Stein, W. E., Lumpkin, A. H.,
Bender, S. C., Spalek, G., et al., “Recent Results of the Los Alamos Free-Electron
Laser,” IEEE J. Quantum Electron., QE-23: 1476–1488, 1987.
4. Christodoulou, A., Lampiris, D., Polykandriotis, K., Colson, W. B., Crooker,
P. P., Benson, S., Gubeli, J., and Neil, G. R., “Study of an FEL Oscillator with a
Linear Taper,” Phys. Rev. E., 66(056502), 2002.