We report on both the theoretical and experimental design of a black phosphorus (BP)-based reflective linear polarizer on Si/SiO substrate in visible range using the Fabry-Perot cavities method. Thanks to the optical anisotropy of BP, polarization wavelength regulation and a high extinction ratio are achievable via optimizing the thickness of BP. Using azimuth-dependent reflectance difference microscopy, we directly measured a huge optical anisotropy of 1.58, corresponding to an extinction ratio of ∼9  dB, from a 96 nm BP on a silicon substrate capped by 260 nm thermally oxidized silicon at a wavelength of 690 nm for the first time, to the best of our knowledge. Our results not only provide a new route to designing nanoscale polarizers based on anisotropic two-dimensional (2D) materials, promoting the application of 2D materials in integrated optoelectronics and system-on-chip, but also suggest a modulation technique for optical anisotropy by integrating the BP film with cavity structures.

Graphene and its clean transfer methods have gathered growing interest and concern in recent decades. Here, we develop a novel large-scale intact transferring technology of paraffin wax onto arbitrary substrates. The wax will then be removed by thermal evaporation, avoiding uncontrollable reactions and leaving no residues. For characterizations, we adopt Raman, FT-IR, XPS, and DRS to measure the optical reflection difference on various surfaces and the thickness of graphene accurately. All the results demonstrate transferred surfaces’ cleanliness and our method’s validity. This technique allows for an effective transfer of graphene and enables a wider range of applications in many fields.

We study computationally the design of a high extinction ratio nano polarizer based on black phosphorus (BP). A scattering-matrix calculation method is applied to compute the overall polarization extinction ratio along two orthogonal directions. The results reveal that, with a resonance cavity of SiO2, both BP/ SiO 2 /Si and h-BN/BP/ SiO 2 /Si configurations can build a linear polarizer with extinction ratio higher than 16 dB at a polarized wavelength in the range of 400 nm–900 nm. The polarization wavelength is tunable by adjusting the thickness of the BP layer while the thicknesses of the isotrocpic layers are in charge of extinction ratios. The additional top layer of h-BN was used to prevent BP degradation from oxidation and strengthens the practical applications of BP polarizer. The study shows that the BP/ SiO 2 /Si structure, with a silicon compatible and easy-to-realize method, is a valuable solution when designing polarization functional module in integrated photonics and optical communications circuits.

No abstract

The yield of a large-area ultra-thin display panel depends on the realization of designed thickness of multilayer films of all pixels. Measuring the thicknesses of multilayer films of a single pixel is crucial to the accurate manufacture. However, the thinnest layer is reaching the sub-20nm level, and different layers feature remarkable divergence in thickness with similar optical constants. This turns to a key obstruction to the thickness characterization by optical spectroscopy. Based on the tiny differences in absorptivity, a fast method for measuring the film thickness in a single pixel is proposed which combines the layer number reducing model and micro-area differential reflectance spectroscopy. The lower layers can be considered as semi-infinite in the corresponding spectral range whose thickness is infinite in the fitting algorithm. Hence, the thickness of the upper layer is fitted in a simplified layer structure. For demonstration, a multilayer silicon microstructure in a single pixel, p-Si/a-Si/n-Si (10nm/950nm/50nm) on complex substrate, is measured. The light spot diameter is about 60 microns with measuring-time in 2 seconds. The measurement deviation is 3% compared by a commercial ellipsometer. To conclude, the proposed method realizes the layer number reduction for fitting multilayer thickness with large thickness difference and similar optical constants, which provides a powerful approach for multilayer microstructure characterizations.