Fiber-to-waveguide coupler based on the parabolic reflector

Area of Science:

• Optoelectronics
• Nanophotonics
• Integrated optics

Background:

• Efficiently coupling light from optical fibers to integrated photonic waveguides is crucial for many photonic applications.
• Existing methods often face limitations in efficiency, bandwidth, polarization dependence, or device size.

Purpose of the Study:

• To introduce a novel fiber-to-waveguide coupling structure, the vertical J coupler.
• To achieve high coupling efficiency, large operational bandwidth, and polarization insensitivity in a compact footprint.

Main Methods:

• The vertical J coupler utilizes a parabolic reflector to redirect and focus light.
• Optical modes from a fiber are coupled normally to the substrate, turned 90 degrees, and focused into a dielectric waveguide.
• Device performance was validated using finite-difference time-domain (FDTD) electromagnetic simulations.

Main Results:

• Simulations demonstrated the potential for high coupling efficiency and broad bandwidth.
• Preliminary fabrication and optical testing confirmed the coupler's viability.
• The design inherently addresses polarization insensitivity.

Conclusions:

• The vertical J coupler presents a promising solution for efficient and robust fiber-to-waveguide interfacing.
• This technology could significantly advance integrated photonic device performance and miniaturization.