Mode matching technique for highly efficient coupling between dielectric waveguides and planar photonic crystal...

Area of Science:

• Photonics and Optical Engineering
• Materials Science

Background:

• Efficient coupling between dielectric silica waveguides (SWG) and planar photonic crystal (PPC) waveguides is crucial for integrated optical circuits.
• Conventional tapered structures often suffer from mode mismatching due to differing waveguide widths, limiting transmission efficiency.

Purpose of the Study:

• To develop and demonstrate a mode matching technique for highly efficient coupling between SWG and PPC waveguides.
• To address mode mismatching by introducing localized defects in PPC tapered waveguides.

Main Methods:

• A mode matching technique utilizing localized defects within a PPC tapered waveguide was designed.
• The introduction and configuration of multiple defects were optimized based on mode mismatching analysis.
• Transmission efficiencies were experimentally evaluated at a wavelength of 1.55 µm.

Main Results:

• Achieved transmission efficiencies exceeding 80% at 1.55 µm.
• Demonstrated significant improvement compared to conventional PPC tapered structures without defects.
• Confirmed the feasibility of the technique for broadband input/output coupling.

Conclusions:

• The defect-engineered mode matching technique offers a highly efficient solution for SWG-PPC waveguide coupling.
• This approach overcomes limitations of conventional methods and enhances optical device performance.
• The technique is suitable for broadband applications in photonic integrated circuits.