Physical optics
2018, 47(S1): 213-218.
doi: 10.3788/IRLA201847.S107001
To achieve nonresonant broadband extraordinary optical transmission (EOT), tapered metallic slits array embedded with rectangular cavities structure was proposed and its transmission properties were investigated using the finite element method (FEM). The results show that tapered metallic slits array embedded with rectangular cavities can achieve broadband and wide-angle enhanced transmission in the infrared and the light is strongly localized enhanced at the slit exits, in contrast with straight slits structure. The phenomenon was described with a transmission line model. In addition, the effects of incident polarization, the entrance width of the slit, and the centers misalignment of the tapered slits on the transmission property were also studied. These results would be helpful for optical signal transmission and the designing near field light harvesting devices with broadband and strong transmission.
2018, 47(12): 1207001.
doi: 10.3788/IRLA201847.1207001
In order to transform a Gaussian beam with uniform polarization into a vector beam with tunable polarization distribution, an optical method was proposed to generate vector beam and control the polarization distribution, based on the polarization characteristics of the S-wave plate and double retarders. Combined with the Stokes-Mueller matrix algorithm, a mathematical model of the polarization control of vector beam was established. And the polarization states distribution of the output beams were calculated, when a linear polarized Gaussian beam passed through the S-wave plate and the double retarders (including two situations:double quarter-wave plates and double half-wave plates). The relationship between the angle of the double retarders and the polarization distribution regular pattern of the output vector beam were discussed. The experimental results agree well with the numerical simulation results, which show that the method can achieve the complex polarization control for a scalar coherent beam, and the correctness of the theoretical analysis is verified.
2018, 47(12): 1207002.
doi: 10.3788/IRLA201847.1207002
A new type of composite vortex beam was generated by the coaxial superposition of two high-order radial Laguerre-Gaussian beams with the same radial indices and opposite topological charges. The intensity distribution characteristic and space propagating property of composite vortex beams were studied theoretically and experimentally. The results show that the composite vortex beam, which is superimposed by the high-order radial Laguerre-Gaussian beam, has a multi-layer bright petal; When the beam waist radius are same, with the increase of propagation distance, the intensity distribution of the beam spreads but does not rotate; When the waist radius are different, the intensity distribution rotates, and the phenomenon of rotating tail appears. The rotating direction and trailing direction depend on the number of topological charges and the size of the waist radius. The results provide an experimental basis for understanding the generation of composite vortex beam and further extending its application scope.
