Ultra-compact terahertz plasmonic wavelength diplexer.

Area of Science:

• Photonics and Wave Phenomena
• Metamaterials and Plasmonics
• Terahertz Technology

Background:

• Terahertz (THz) spoof surface plasmon polariton (SPP) waveguides offer subwavelength confinement for low-loss THz wave transmission.
• Existing THz wavelength division multiplexing devices often lack compactness, limiting integration in communication systems.

Purpose of the Study:

• To design and demonstrate an ultra-compact wavelength diplexer utilizing THz spoof SPP waveguiding structures.
• To engineer coupling length and achieve frequency-selective signal routing in a miniaturized device.

Main Methods:

• Design of a THz spoof SPP waveguide-based directional coupler.
• Incorporation of periodic pillars in the coupling region to engineer effective refractive index.
• Adjustment of pillar parameters to control coupling length and achieve port-selective signal output at target frequencies.

Main Results:

• An ultra-compact wavelength diplexer with a length of 1.6 mm (12.8% of traditional counterparts) was realized.
• Simulated minimum transmittances of -24.34 dB and -26.27 dB at 0.637 THz and 0.667 THz, respectively.
• Insertion losses below 0.46 dB and extinction ratios exceeding 19 dB were achieved at both operating frequencies.

Conclusions:

• The proposed device offers a significant size reduction for THz wavelength diplexers.
• Cascading these diplexers can lead to compact multi-channel THz wavelength demultiplexers.
• The technology holds promise for advancing THz integrated communication systems.