Large-area, 100mm in diameter, aluminum nanowire grids with 40nm line/78nm space were fabricated with full-wafer immersion interference lithography. The aluminum nanowire grids with a 59nm half-pitch work as a highly efficient optical polarizer for deep ultraviolet wavelength down to ∼250nm. In addition, an extremely high contrast from 10 000:1 to 50 000:1 was achieved across the whole visible and near-infrared wavelength range, along with good transmittance (85%–90%). The broadband large-area high-performance polarizer operating down to deep ultraviolet wavelength opens up applications including semiconductor lithography and metrology applications.
Both high contrast and high transmittance are preferred for optical polarizers. To achieve high transmittance for aluminum nanowire-grid polarizers, a narrow linewidth is required. In this letter, aluminum nanowire-grid polarizers with 30-nm-wide linewidth and 200nm depth were fabricated by UV-nanoimprint lithography, which leads to ultrahigh transmittance. To achieve a high contrast, the authors fabricated the 30-nm-wide aluminum nanowire structures on both sides of the glass wafers. An extremely high contrast up to 10 000:1 was achieved, in the visible range, along with good transmittance of 83%–87% for the double-side aluminum nanowire-grid polarizers.
We wrapped 150 nm period aluminum wire grid polarizer (WGP) with AlSiOx by using atomic layer deposition at 250 degrees C. The nanometer precision coating defined the spacer to double the spatial frequency of the 100 mm diameter grating fabricated by using a legacy immersion holography setup at 351 nm wavelength. Half-pitch grating of approximately 38 nm was demonstrated with good pattern uniformity, excellent repeatability, and a wide processing window. We believe 10 nm half-pitch grating over even larger areas are viable, overcoming one major hurdle to commercialize nanoimprint.
117 and 150nm pitch polymer gratings were successfully fabricated on plastic substrate over large area by nanoimprint lithography. Nanowire-grid polarizers were made by depositing Al on the sidewalls of the gratings at oblique angles. The effects of grating period, grating linewidth, Al depth, and thickness were studied in detail. Excellent contrast (∼1000:1) and high transmittance (80%–90%) (without antireflection coating) at the wavelength of 500nm and above were demonstrated.
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