Imprinted diffractive optics for terahertz radiation

Area of Science:

• Optics and Photonics
• Materials Science
• Terahertz Technology

Background:

• Terahertz (THz) diffractive optic elements are crucial for manipulating THz radiation.
• Efficient fabrication of complex THz optical structures in high-transmission materials remains a challenge.
• Polypropylene offers excellent transmission in the THz range but requires suitable fabrication methods.

Purpose of the Study:

• To develop a rapid and high-fidelity method for fabricating terahertz diffractive optic elements.
• To demonstrate the effectiveness of imprinting with silicon masters for creating multilevel diffractive optics.
• To evaluate the performance of fabricated Fresnel lenses at terahertz frequencies.

Main Methods:

• Fabrication of an eight-phase-level silicon master using inductively coupled plasma reactive ion etching.
• Replication of the silicon master pattern onto polypropylene using imprinting.
• Characterization of the fabricated diffractive optic elements using a 2 THz quantum cascade laser.

Main Results:

• Successful replication of complex, multilevel diffractive optical structures in polypropylene.
• Demonstration of excellent replication fidelity for high-efficiency Fresnel lenses.
• Achieved a 70-fold increase in signal strength at the focal point of the fabricated lenses.

Conclusions:

• Imprinting with silicon masters is a viable and rapid technique for producing high-efficiency terahertz diffractive optics.
• The fabricated polypropylene lenses exhibit high performance for terahertz applications.
• This fabrication method enables the creation of advanced optical components for terahertz systems.