Deflection of a monochromatic THz beam by acousto-optic methods
Journal Article
·
· Quantum Electronics (Woodbury, N.Y.)
- Department of Physics, M.V. Lomonosov Moscow State University (Russian Federation)
- G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)
- Novosibirsk National Research State University, Novosibirsk (Russian Federation)
The possibility of controlled deflection of an electromagnetic THz beam of a free-electron laser by acousto-optic (AO) methods has been demonstrated for the first time. The material of the AO deflector was chosen to be single-crystal germanium, which has a fairly large refractive index (n = 4.0) and a relatively low absorption coefficient for electromagnetic waves. The absorption coefficient α in germanium is 0.75 ± 0.02 cm{sup -1} at a wavelength λ = 140 μm. The diffracted beam intensity is shown to be maximum at an effective AO interaction length l = 1/α. A diffraction efficiency of 0.05% at a travelling acoustic wave power of 1.0 W is experimentally obtained. It is established that a change in the ultrasonic frequency from 25 to 39 MHz leads to variation in the external Bragg angle in the range from 19.5° to 27.5°. At a fixed Bragg angle θ{sub B} = 22.4° the frequency band of diffraction is 4.2 ± 0.1 MHz and the angular range of laser beam scanning reaches 2.5° ± 0.5°. The results obtained indicate that AO interaction can be used for controlled deflection of electromagnetic THz beams. (terahertz radiation)
- OSTI ID:
- 22373652
- Journal Information:
- Quantum Electronics (Woodbury, N.Y.), Journal Name: Quantum Electronics (Woodbury, N.Y.) Journal Issue: 12 Vol. 43; ISSN 1063-7818
- Country of Publication:
- United States
- Language:
- English
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