Compact and low-loss bent hollow waveguides with distributed Bragg reflector

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanotechnology

Background:

• Planar light wave circuits require efficient waveguide bends for miniaturization.
• Distributed Bragg reflectors (DBRs) are crucial for optical device performance.
• Silicon photonics offers a platform for integrated optical systems.

Purpose of the Study:

• To theoretically and experimentally present a hollow bent waveguide with DBRs on a silicon substrate.
• To investigate bending transmission efficiencies of arc- and cut-type 90-degree bends.
• To assess the potential for increased integration density in photonic integrated circuits.

Main Methods:

• Utilized the two-dimensional finite-difference time-domain (FDTD) method for simulations.
• Fabricated waveguides with an air core embedded by Si3N4/SiO2 multilayer stacks.
• Employed plasma-enhanced chemical vapor deposition (PECVD) for multilayer deposition.

Main Results:

• Simulated and experimentally validated bending transmission efficiencies for 90-degree bends.
• Achieved a lowest bending loss of approximately 3.9 dB for arc-type waveguides.
• Achieved a lowest bending loss of approximately 0.8 dB for cut-type waveguides.

Conclusions:

• The developed hollow bent waveguide with DBRs shows promise for optical integration.
• The cut-type bending design offers significantly lower loss compared to arc-type.
• This technology facilitates higher density integration in planar light wave circuits.