Acoustic attenuation in L[001] tellurium dioxide

Acoustic attenuation is a critical material-dependent parameter which ultimately limits the efficiency of an acousto-optic (AO) device. The loss in efficiency associated with acoustic attenuation is a result of the absorption of power from the acoustic beam into the AO material crystalline lattice through viscous damping and harmonic depletion. In long time-aperture AO devices (such as Bragg cells and acousto-optic tunable filters) acoustic attenuation limits the device time-aperture and hence the device resolution. Reported values of the acoustic attenuation due to viscous damping in the acousto-optically important L[001] mode of TeO₂ range from 4 to 6.2 dB/μs/GHz². We have recently measured acoustic attenuation in an L[001] mode TeO₂ AO Bragg cell. We observed a power dependence to the acoustic attenuation and show that this is the result of absorption into higher nonlinear modes in the lattice. We find that the attenuation due to viscous damping is only 2.3 dB/μs/GHz².