Acousto-Optic Tunable Filter (AOTF) Revisited: Ultrashort Optical Pulses Crosstalk Studies on the Lossy Filter

Abstract

We examine again the crosstalk level (Xtalk) and extinction ratio (Xratio) of an acousto-optic tunable filter (AOTF) operating with ultrashort light pulses (2 ps), now considering the loss effect. The compression factor was studied for the switched pulse with lossy AOTF (α dB = 4 dB/mm) considering five nonlinearity profiles. One can observe that there is always an optimum value for δ (final value of the nonlinearity) that one can obtain a switched pulse with the same time duration of the input pulse (C = 1). The compression factor for the switched pulse along the filter length shows that for the constant profile, the compression factor is around 1 all over the device. The study of the crosstalk level (Xtalk) of this device, considering the optimum values of δ obtained from the compression studies, as a function of the pump power (P 0 ) was done. The acousto-optic tunable filter (AOTF) has attracted great attention in recent years, in part because it appears to be a suitable basis for multi-wavelength optical cross-connects. It is probably the only known tunable filter that is capable of selecting several wavelengths simultaneously. This capability can be used to construct a multi-wavelength router.

Optical Bistability in an Acousto-Optic Tunable Filter (AOTF) Operating with Short Optical Pulses

“…where c is velocity of light in the vacuum. The manufacturing process of AOTF and the physical consequences of the choice of the material used to its construction can be found elsewhere [26][27][28][29]. In our study we are considering a centro-symmetric material, as the germanium crystal (Ge), to avoid the presence of the effects of second-order [χ (2) ] nonlinear susceptibility.…”