Measuring light’s information of polarization and phase in real time is very important in optics. Since metasurfaces enable the wavefront manipulation, which can replace some conventional optical components and make the system extremely compact. Here, we apply the concept of metasurface to system level, creating a generalized Hartmann-Shack array based on 3×2 sub-arrays of silicon-based metalenses for optical multi-parameters detection, which not only measures phase and phase-gradient profiles of optical beams but also measures spatial polarization profiles at the same time. The silicon-based metalenses, with a numerical aperture of 0.32 and a mean measured focusing efficiency in transmission mode of 28% at a wavelength of 1550 nm. Furthermore, we demonstrate detections of a radially polarized beam, an azimuthally polarized beam and a vortex beam.
Recently, it was demonstrated by J.K. Gansel et al. that three-dimensional single-helical metamaterials can serve as
broadband circular polarizers in the infrared range. Firstly, in this paper, we used the finite difference time domain
(FDTD) method to study circular polarizers with double-helical metamaterials. The results show that the operation bands
are more than 50% broader than those of the single-helical structures. However, we also notice that the signal-to-noise
(S/N) ratios of them are both poor (~10 dB). Secondly, we analyzed the performances of triple-helical structures. It is
obvious that the triple-helical circular polarizer has not only a broad operation band, but also a much higher S/N ratio
(~35 dB) than single- and double-helixes.
Block copolymers (BCPs), which self-assemble into spatially periodic one-dimensional (1D) ordered lamellar equilibrium structures, can be used as multilayer waveguide materials. In this article, the hybrid modal characteristics of three representative self-assembled BCPs multilayer stripe waveguides were studied with compact 2D finite-difference time-domain (2D-FDTD) method. By comparing our numerical results with those obtained by the N-layer waveguide formalism, it is found that on some occasions the two-dimensional (2D) formalism is a good choice to substitute for the three-dimensional (3D) modal analysis of multilayer waveguide . It is also been proved that if the sequence of the two different index layers is inverted in the structure, the modal analysis results change dramatically and the lamellar width is an important factor that influences the optical field distribution of the waveguide modes. An investigation about the triblock copolymer (tri-BCP) waveguide revealed that its field distribution layered more obviously for the particularity of tri-BCP waveguide core structure.
In this paper, Lichtennecher method and module system simulation method were synthesized to present a formula giving the relation between the effective refractive index and pore-ratio of the polymer nanoporous film made of PS(polystyrene) PMMA(polymethyl-methacylate) and nano-pore. It can be used to design a nanoporous polymer film whose effective refractive index can be fine-tuned with great precision, which is of great importance and pratical value for the design and manufacture of the high performance nanoporous polymer optical waveguide whose effective refractive index difference between the core and the cladding is perfectly controlled and adjusted.
Nano-porous polymer material is recently developed and is of very important practical value in optical field. In this paper, nano-porous polymer films which can be used in optical planar waveguide were studied. The refractive index of this kind film can be controlled and adjusted precisely. Through changing the volume fraction of PS in the film, the relationship between the effective refractive index and the pore volume ratio in the film was found with the scanning electron microscope and ellipsometry. The effective refractive index decreases with the increase of the pore volume ratio. The propagation characteristics of the fields in a nano-porous polymer planar waveguide were simulated with the Finite Difference Time Domain (FDTD) method and the result of the experiment was confirmed with the FDTD method too.
In this paper, the propagation characteristics of the fields in a planar waveguide, a synchronous-waveguides and a s-bended waveguide were simulated with the Finite Difference Time Domain (FDTD) method. The distribution graphs of the field intensities for the simulated optical waveguides were obtained. Coupling lengths were gained from the data of graphs. By comparing these results with that simulated with beam propagating method (BPM), it is concluded that during simulating waveguide with relatively simple structure the simulation performed by the FDTD method are better in accord with the BPM analysis, but with relative complex structure such as the s-bended waveguide the FDTD method can simulated much better than the BPM dose. So during simulating waveguide with complex structure the FDTD method is the better option.
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