講演情報
[21p-P18-10]Entangled Elegant Vortex Vector Beams and Optical Sensensing
〇Wen-Hsuan Kuan1, Chin-Tai Huang1,2, Yang-Jui Chang1,2, Kuei-Huei Lin1 (1.Univ. of Taipei, 2.Chengchi Univ.)
キーワード：
elegant vortex vector beam、entanglement、optical sensor
Light carries nonzero orbital angular momentum (OAM) is confirmed and is termed the optical vortex (OV). The vector beam (VB) refers to the light with non-uniform transverse polarization distributions. For laser beams having definite OAM and spatially nonhomogeneous polarization (SNP) are called vortex vector beams (VVB). A three-dimensional surface topography with phase information can be provided using the holographic technique or the spatial light modulator (SLM). In this work, we establish a Mach-Zehnder interferometer (MZI) -based optical sensor. Adjusting the magnitude of OAM carried by the two polarized OVs makes the generation of a CVB or VVB tunable. Furthermore, the polarization control of the co-propagation of the incident Gaussian beam and the reflected OVs can cause the nonorthogonal combination and leads to the experimental realization of the entangled vectorial elegant Laguerre-Gaussian (eLG) modes. As beams are usually designed for propagation through first-order optical systems with certain rotational symmetries, under modified Iwasawa decomposition, the free space beam propagation can be described appropriately via the symmetric fractional Fourier transform. Since the intensity and phase distributions of an eLG mode would vary sharply in the Rayleigh length, the entangled vector eLG with SNP and phase distribution provide a unique quantum key distribution for multichannel communication. We show that by synchronous monitoring of the beam profile, interference fringe contrast, and state of polarization of the optical field, any local threat from external optical tapping can be distinctively identified. By particular polarization and mode selections, the OAM bandwidth in terms of vectorial eLG modes can be increased, which may lead to a flattening of the spectrum and create higher dimensionality in the entangled state. The verification of entanglement in terms of vectorial eLG modes is also performed via a Bell-type experiment.