Controllable photonic hooks generated by typical shapes composed of uniaxial crystals

Abstract

This work reports on the theoretical study and results on the generation and control of photonic hooks (PHs) through uniaxial crystals (calcite as an example). Completely different mechanisms and effects are obtained in typical rectangular and cylindrical structures, respectively. PHs generated by the rectangular structure no longer have a single inflection point but have a specific dual-inflection-point feature. The calcite cylindrical structure can generate a PH with a size comparable to that of the structure, and dynamic adjustment can be achieved through the angle between the incident and optical axes. By changing the polarization state of the incident field, active switching between photonic nanojet and PH can be achieved in both types of structures. The proposed generation and modulation scheme can be extended to other anisotropic materials.