We demonstrate experimentally a transition from nonlinear beam trapping to defocusing in a two-dimensional periodic photonic structures by varying the modulation depth of the lattice. The observed effect illustrates the fundamental crossover from discrete to cw transport mechanisms. At the threshold modulation, the output beam is highly sensitive to refractive index and power variations, which can be potentially applied for high-sensitivity refractive index or temperature sensing.
© 2010 Optical Society of America
Original Manuscript: June 25, 2010
Manuscript Accepted: August 25, 2010
Published: September 22, 2010
Francis H. Bennet, Inés A. Amuli, Andrey A. Sukhorukov, Wieslaw Krolikowski, Dragomir N. Neshev, and Yuri S. Kivshar, "Focusing-to-defocusing crossover in nonlinear periodic structures," Opt. Lett. 35, 3213-3215 (2010)