Tuning Optical Angular Momentum In Optical Superlattice Under Electro-Optic Effect

In 1909 Poynting realized that circularly polarized light has spin angular momentum However, the idea of orbital angular momentum (OAM) of light came much later. In 1992, Allen et al recognized that a light beam can carry OAM which is associated with its spiral phase front OAM allows for qudits while spin realizes only one qubit In 2002 a research group in Glasgow University suggested an interferometric method to distinguish single photons based on individual OAM which makes loading more information onto a 2001 is another breakthrough, and that demonstrated the photon pairs from pararnetric down-conversion showed high-dimensional OAM entanglement. Until now, photon angular momentum has many applications, ranging from manipulation of cooled atoms, optical spanner, rotational quantum communication and Doppler shift to quantum entanglement. However, the manipulation of photon angular momentum by means of nonlinear optics and its applications in quantum information protocols and quantum entanglement (including single-photon entanglement and hyperentanglement) are still rare In particular, the high-dimenional OAM has not been fully exploited in the field of quantum information yetMany researches have suggested many kinds of means to generate angular momentum. The OAM generated by using EO effect was initially advised in this paper. We systematically investigate the polarization, the spin angular momentum and the orbital angular momentum of output light under EO effect. The main results and points included in this paper are summarized as followsBased on the coupling theory, we study the characters of Gaussian beam propagating in PPLN and the OAM distribution of the output light. For different applied fields, beam waists, and crystal lengths, the OAM distribution on the transverse section changes. These results will play an important role in the area of manipulation.Under EO effect, light beams with spiral phase in HPPLN, coupled out of the crystal. The evolution of polarization of output beam is investigated. For different applied fields, SAM and OAM, total SAM and total OAM are also studied. All these special characters can help on making EO modulator. These natures of HPPLN may find applications in polarization state control and angular momentum switch.