Silicon-based diffractive optics for structured light in nonparaxial terahertz imaging systems

In this communication, we consider principles of design and assembling of nonparaxial THz imaging systems based on silicon diffractive optics components. The investigation is dedicated to lensless photonic setups comprising high-resistivity silicon-based DOEs such as Fresnel zone plates, Fibonacci lenses, Bessel axicons, and Airy zone plates, all fabricated from a high-resistance 500 μm thick silicon substrate by femtosecond laser ablation. The exploration underlines the significance of structuring both the illumination and light-collection schemes as well as assembly principles of silicon diffractive optical elements in compact THz imaging.