THz waveguide adapters for efficient radiation out-coupling from double metal THz QCLs

Area of Science:

• Optics and Photonics
• Semiconductor Devices
• Terahertz Technology

Background:

• Terahertz (THz) quantum cascade lasers (QCLs) are crucial for various applications.
• Efficiently coupling THz radiation from QCLs into optical fibers remains a challenge.
• Existing methods often lack versatility and efficiency.

Purpose of the Study:

• To develop novel on-chip optical components for improved THz QCL out-coupling.
• To demonstrate beam reshaping and enhanced radiation coupling efficiency.
• To provide a versatile solution for integrating THz QCLs with optical fiber systems.

Main Methods:

• Incorporation of cyclic-olefin copolymer (COC) dielectric optical fibers onto the QCL facet.
• Design and assembly of a micromachined feed-horn waveguide around the THz QCL.
• Integration of a slit-coupler for efficient radiation extraction.
• Characterization of beam divergence and coupling efficiency.

Main Results:

• Achieved visible reshaping of the optical beam, independent of waveguide configuration.
• Demonstrated a ± 20° beam divergence.
• Showcased potential for high-efficiency radiation coupling from metal-metal waveguides into optical fibers.
• Successful integration of COC optical fibers and feed-horn waveguides with THz QCLs.

Conclusions:

• The developed on-chip optical components significantly enhance THz QCL out-coupling.
• The integrated system offers a pathway to high-efficiency fiber coupling for THz radiation.
• This advancement holds promise for practical applications requiring efficient THz signal transmission.