Observation of beam deflection in one-dimensional photonic lattice in LiNbO3 crystal accompanied with self-focusing and self-defocusing nonlinearities

• By adjusting the temperature, the nonlinearity in LiNbO3 crystal can be changed from self-focus to self-defocus.
• The beam forms a deflected discrete bright circle soliton in the photonic lattice when the sample's temperature is changed.
• Our studies provide a simple way to create complex optical circuits inside the nonlinear crystal without biased field.
• The deflection effect has a potential application in the field of optical switch and optical deflector.

We numerically and experimentally investigated the deflection of a laser beam in a photo-induced one dimensional (1D) photonic lattice (PL) in a pure LiNbO3 crystal accompanied with self-focusing and self-defocusing nonlinearities, respectively. The results show that the probe beam will be self-focused or self-defocused when the sample temperature is increased or decreased. Moreover, the light beam deflects to the direction of heat flux if there exists an additional temperature difference between the two lateral sides of the sample. The probe beam forms a deflected discrete circle soliton in the PL when the sample temperature is increased from 25 °C to 45°C and the additional temperature difference is ±5 °C. Our simulation results are in agreement with the experimental observation.