Design and fabrication of a SiC chiral lens using spiral microstructures

Abstract

Polarization devices are essential components in optical systems, enabling the control and tuning of light polarization. Silicon carbide (SiC) stands out in this context due to its high refractive index, low absorption, and resistance to environmental conditions. In this work, we present the design, fabrication, and optical evaluation of SiC chiral lenses. The spiral patterns on the SiC wafer surface were fabricated using ultraviolet picosecond laser etching with both clockwise and counterclockwise orientations. The etching process achieved nanometer-scale depths with micrometer-scale pattern pitches. Optical simulations were performed and demonstrated good agreement with the experimental results. To assess the chiral performance of the fabricated lenses, circular dichroism (CD) spectroscopy was employed. CD measures the differential absorption of left- and right-handed circularly polarized light in chiral structures. Here, SiC as a material for chiral lenses, leveraging its exceptional thermal stability, high breakdown field strength, and strong radiation resistance for enhanced durability and performance in high-power and high-temperature applications. Additionally, by optimizing etching patterns or applying surface coatings, SiC chiral lenses can be customized for specific wavelength applications. The proposed SiC chiral lenses achieved a CD value of 300 mdeg, demonstrating their potential for polarization control.