Monolithic beam splitter in silicon-on-insulator

Area of Science:

• Photonics
• Materials Science
• Nanofabrication

Background:

• Monolithic beam splitters are crucial components in photonic integrated circuits.
• Fabrication imperfections can significantly impact device performance and introduce optical losses.

Purpose of the Study:

• To fabricate a monolithic 1x2 T-branch beam splitter using silicon-on-insulator (SOI) technology.
• To evaluate the performance and quantify optical losses associated with the fabricated beam splitter.

Main Methods:

• Inductively coupled plasma reactive ion etching (ICP-RIE) for device fabrication.
• Near-field imaging to assess beam splitter functionality.
• Atomic force microscopy (AFM) to measure surface roughness of mirror and waveguide sidewalls.

Main Results:

• The symmetric 1x2 T-branch beam splitter was successfully fabricated and demonstrated effective operation.
• Sidewall surface roughness of the rib waveguide was evaluated via corner mirror roughness measurements.
• Scattering losses were quantified at 0.5 dB/cm for sidewalls and 0.2 dB/mirror for corner mirrors.
• The overall fiber-waveguide insertion loss was measured to be approximately 5.0 dB.

Conclusions:

• The ICP-RIE fabrication method is suitable for creating monolithic beam splitters on SOI wafers.
• Surface roughness significantly contributes to optical scattering losses in the fabricated devices.
• The quantified losses provide critical data for optimizing future photonic integrated circuit designs.