Fabrication and performance study of subwavelength metallic grating via nanoimprint lithography

• A new method for fabricating subwavelength metallic gratings using NIL is proposed. • A vibration-assisted nanoimprinting system was constructed. • High quality dielectric gratings successfully fabricated via vibration-assisted NIL. • The prepared grating exhibits excellent performance in the visible light spectrum. Subwavelength metallic gratings exhibit significant application potential due to their superior polarization characteristics and high structural stability, highlighting the urgent need for an efficient and cost-effective fabrication method. This study proposes, for the first time, a vibration-assisted nanoimprinting approach to fabricate subwavelength metallic gratings, achieving high-quality structures with outstanding polarization performance in the visible spectrum. A mathematical model was developed to analyze the effect of normal vibration on photoresist filling, providing insights into the underlying mechanism of enhanced filling efficiency. Numerical simulations were conducted to evaluate the influence of metallic materials and structural parameters on polarization performance. To implement this concept, a non-resonant vibration device was designed, and a vibration-assisted nanoimprint system was constructed to introduce normal vibration during the imprinting process. The effectiveness of vibration application was verified through vibration-assisted nanoimprinting experiments, in which the average width of the dielectric grating increased from 115 nm to 120 nm (a 4% improvement), and the average height increased from 118 nm to 136 nm (a 12% enhancement). Subwavelength metallic gratings were subsequently fabricated via a coating process and subjected to detailed performance characterization. When the incident angle varied within ± 30°, the average TM-wave transmittance exceeded 40.45%, while the average extinction ratio reached 21.3 dB. Across the visible spectrum, the TM wave showed an average transmittance of 45.41% and an extinction ratio of 20.39 dB, demonstrating excellent polarization performance. These findings confirm that vibration-assisted nanoimprinting is a promising and efficient technique for fabricating subwavelength metallic gratings.