Study of the characteristics of the two polarized optical waves of non-collinear acousto-optical tunable niters

摘要

This paper analyzes the effects of birefringences of acousto-optical crystals on the diffraction angle of the o and e beam, deduces the exact tuning relationship between the two diffracted polarized beams in large-aperture and non-collinearAOTFs, and explores the influence of birefringences on the wavelengths difference of the two diffracted beams, AA, acoustical angle 0a, and relation between the external angle of incidence 9i and the ultrasonic frequency f. Theoretical calculations show, that the difference of the internal angles of incidence of the two diffracted beams, 8ie-9io, varies in the range of 0°~1.5° in accordance with the change of the external angle of incidence, and that the maximum wavelengths difference of the diffracted beams of order± 1 can be as much as 80 nm. The direction θa of the acoustical vector is approximately 108.8°, which satisfies the conditions of momentum match and wavelengths difference to be zero for diffracted beams of order±l , but the internal angle of incidence varies about θie=55.6°, and the range can reach1.4°. The obtained theoretical results are verified by experiments to measure the diffracted beams of order ±1 of mid-infrared AOTF.