Hybrid encryption approach utilizing OAM wavefronts and polarization sensitive metasurface

With the rapid advancements in quantum structures, reliance on traditional software-based encryption systems is no longer fully viable. In this context, it is essential to shift our perspective on encryption systems and adopt a hybrid approach combining software and hardware encryption to withstand new attacks characterized by high power and speed. To this end, we have designed a metasurface that can operate statically while employing a dynamic structure by engineering input polarization relative to output polarization. Specifically, when polarization x is incident on our structure, half of the power is converted to polarization y, which represents the cross-polarization, while the other half remains in the original polarization x, referred to as co-polarization. By appropriately arranging the unit cells in the co-polarization, we achieve a superposition of two modes L = −1, ＋1 for the OAM wavefront, while in the cross-polarization, we obtain a superposition of two modes L = −3, ＋3. The same conditions apply to polarization y, where in polarization x or cross, we have a superposition of two modes L = −3, ＋3, but in polarization y or co, the superposition yields two modes L = −2, ＋2. This metasurface is combined with software-based XOR encryption, complicating the task for unauthorized eavesdroppers.