Tunable wide angle acousto-optic filter applying single crystal telluriumстатья
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Дата последнего поиска статьи во внешних источниках: 18 декабря 2015 г.
Аннотация:The acoustic, optic and acousto-optic properties of tellurium crystals have been examined in
order to develop an acousto-optic tunable filter (AOTF) operating in the long-wave infrared
(LWIR) region. The AOTF design is based on the wide-angle regime of light diffraction in the
YZ plane of the birefringent crystal operating from 8.4 to 13.6 m. Device characteristics
were obtained from both theoretical and experimental investigations. Experiments were
carried out using both a 10.6 m pulsed CO2 laser as well as a tunable CO2 laser operating in
a continuous wave mode from 9.2 to 10.7 m. The AOTF was tuned over the acoustic
frequency range of 81.5–94.7 MHz. The filtering performance in the tellurium device was
provided by a pure shear elastic wave propagating at a 95.8 angle with respect to the positive
direction of the optic axis, while an ordinary polarized optical beam was incident at the Bragg
angle of 6.0 relative to the acoustic wavefront. At 10.6 m, the measured spectral bandwidth
of the filter was 127 nm and the optical transmission coefficient was around 8.8% with 2.0 W
drive power. This paper presents detailed results from both the theoretical as well as
experimental device characterization including the spectral images obtained with a 256 256
mercury cadmium telluride camera cooled to 77 K.