Broadband polarizer using single-layer grating with ultra-high extinction ratio

Polarizers are an essential optical element for tailoring the polarization state of electromagnetic waves in a wide range of optical devices. Such polarizers, which exhibit a wide operating bandwidth and high performance, are attracting increasing attention, due to their extensive prospects for use in applications ranging from polarization imaging, to optical communications and detection, among others. However, achieving both broadband performance and ultra-high extinction ratio (ER), and that simultaneously, is still challenging in the design of effective polarizers. To tackle that demand, in this work, an Au-on-silica grating structure has been proposed as the basis of the design of a miniaturized high-efficiency polarizer that practically can cover the entire visible and near-infrared spectral ranges. The single-layer polarizer thus designed can show an ER of 60 dB in this spectral domain, and it has been shown that the geometrical parameters selected have a significant effect on the performance characteristics of the polarizer. Furthermore, an ER of similar to 150 dB could be achieved merely by regulating the thickness of the grating to achieve the optimum performance. By integrating the high-performance polarizer proposed in this work with an optical fiber meta-tip, a refractive polarizer with a value of the ER of >45 dB, and that over the entire spectral domain considered, has been demonstrated. Such an approach offers an alternative route to achieving a broadband, powerful, and flexible processing polarizer design.

Automated summary

In this study, a miniaturized high-efficiency polarizer based on an Au-on-silica grating structure has been proposed, which can cover the entire visible and near-infrared spectral ranges with an extinction ratio (ER) of 60 dB in this range. By regulating the thickness of the grating, an ER of up to 150 dB can be achieved. By integrating this high-performance polarizer with an optical fiber meta-tip, a refractive polarizer with an ER value of >45 dB over the entire spectral range has been demonstrated.