A low-loss molybdenum plasmonic waveguide: perfect single-crystal preparation and subwavelength grating optimization

Area of Science:

• Optoelectronics and Nanophotonics
• Materials Science and Engineering

Background:

• Plasmonic waveguides confine photons below the diffraction limit, crucial for advanced optical devices.
• Molybdenum (Mo) shows promise for light trapping and field confinement, particularly at 1.55 μm.
• Fabricating high-quality Mo plasmonic waveguides and studying their surface plasmon behavior remains challenging.

Purpose of the Study:

• To fabricate and characterize single-crystalline Mo microrod plasmonic waveguides.
• To investigate the surface plasmon polariton behavior in Mo structures using fabricated diffraction gratings.
• To demonstrate efficient waveguide performance of Mo for near-infrared applications.

Main Methods:

• Preparation of a single-crystalline Mo microrod waveguide.
• Fabrication of subwavelength diffraction gratings on the Mo microrod.
• Design, optimization, and etching of gratings to excite surface plasmon polaritons.
• Characterization of waveguide performance, including propagation length and transmission loss.

Main Results:

• Successfully fabricated subwavelength gratings on a single-crystalline Mo microrod.
• Achieved the first demonstration of surface plasmon polariton behavior in Mo structures.
• Observed highly efficient waveguide performance in the near-infrared spectrum.
• Measured a long propagation length of 32 μm and low transmission loss of 0.067 dB/μm.

Conclusions:

• Single-crystalline Mo microrod waveguides with diffraction gratings exhibit excellent plasmonic properties.
• This work validates Mo as a viable material for advanced plasmonic waveguide applications.
• The findings offer new avenues for materials research and optical device development.