Abstract
We present experimental and theoretical investigations on the polarization properties of a single- and a double-layer gold (Au) grating, serving as a wire grid polarizer. Two layers of Au gratings form a cavity that effectively modulates the transmission and reflection of linearly polarized light. Theoretical calculations based on a transfer matrix method reveals that the double-layer Au grating structure creates an optical cavity exhibiting Fabry-Perot (FP) resonance modes. As compared to a single-layer grating, the FP cavity resonance modes of the double-layer grating significantly enhance the transmission of the transverse magnetic (TM) mode, while suppressing the transmission of the transverse electric (TE) mode. As a result, the extinction ratio of TM to TE transmission for the double-layer grating structure is improved by a factor of approximately 8 in the mid-wave infrared region of 3.4–6 μm. Furthermore, excellent infrared imagery is obtained with over a 600% increase in the ratio of the TM-output voltage (Vθ = 0°) to TE-output voltage (Vθ = 90°). This double-layer Au grating structure has great potential for use in polarimetric imaging applications due to its superior ability to resolve linear polarization signatures.
Highlights
We present experimental and theoretical investigations on the polarization properties of a singleand a double-layer gold (Au) grating, serving as a wire grid polarizer
A multiple-layer model based on the transfer matrix method reveals that both the transverse magnetic (TM) transmission and the extinction ratio of the double-layer Au grating can be improved by selecting an appropriate thickness of a dielectric embedded between two layers of the Au grating, leading to a Fabry-Perot cavity resonance
We find that the extinction ratio (Vθ=0 /Vθ=90 ) using the captured IR images is obtained with ~14 and ~86 for the single- and the double-layer Au grating structures, respectively
Summary
We have nanoimprint-lithographically fabricated a highly polarization-sensitive, dielectric cavity bounded between two layers of gold grating. The architecture of the double-layer Au grating brings the advantages of stacking 1D subwavelength gratings, such as the sequential attenuation of the linearly polarized light parallel to the grating direction (TE or θ = 90 ), while maintaining the advantages of an optical cavity exhibiting FP resonance modes, such as the enhanced transmission of linearly polarized light perpendicular to the grating direction (TM or θ = 0 ). The ratio of TM- to TE-transmitted light intensity for the double-layer grating structure is experimentally × 8 higher in the MWIR region as compared to the single-layer Au grating. This FTIR-measurement result is supported by the multiple-layer model based on a transfer matrix method. Our findings suggest that the double-layer Au grating structure is very promising as a superior microgrid polarizer for the generation high-performance polarimetric imaging systems
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
