Talbot effect in binary waveguide arrays

Abstract: We study the Talbot effect in binary waveguide arrays (BWAs). Like in conventional waveguide arrays, the Talbot effect can only occur if the input signal has the period equal to $N$ = 1, 2, 3, 4, and 6 in the transverse direction. However, unlike in conventional waveguide arrays, for observation of the Talbot effect with $N$ = 3, 4, and 6 in BWAs, parameter $\sigma$ representing half of the propagation constant mismatch between two adjacent waveguides must have some specific values. Meanwhile, for observation of the Talbot effect with $N$ = 1 and 2 in BWAs, $\sigma$ can get any real values. We also analytically derive the Talbot distance along the longitudinal axis of BWAs where the recurrence of the input signal happens both in phase and intensity. Moreover, we also analytically find the intensity period where the field intensity is repeated during propagation. In some cases, the intensity period is equal to half of the Talbot distance, whereas in other cases, these two periods are just equal to each other. All these new analytical results are perfectly confirmed by beam propagation simulations in BWAs.