Etch-free low loss silicon waveguides using hydrogen silsesquioxane oxidation masks

Area of Science:

• Photonics and Optical Engineering
• Materials Science and Engineering
• Nanofabrication

Background:

• Silicon-on-insulator (SOI) technology is crucial for integrated photonics.
• Traditional fabrication methods for silicon waveguides often involve complex and damaging etching processes.
• Minimizing optical loss in waveguides is essential for efficient photonic device performance.

Purpose of the Study:

• To develop and demonstrate an etch-free fabrication technique for low-loss silicon waveguides.
• To bypass traditional wet or dry etching steps in waveguide fabrication.
• To characterize the performance of waveguides fabricated using the novel method.

Main Methods:

• Utilized a silicon-on-insulator (SOI) chip.
• Employed a hydrogen silsesquioxane (HSSQ) mask patterned via electron-beam lithography.
• Applied a single local oxidation step to convert HSSQ to a glass-like compound and define waveguides simultaneously.

Main Results:

• Achieved an etch-free fabrication process for silicon waveguides.
• Fabricated ring resonators to characterize waveguide losses.
• Measured intrinsic Q-factors as high as 1.57 × 10^6.
• Determined waveguide losses as low as 0.35 dB/cm.

Conclusions:

• The proposed local oxidation technique offers an efficient, etch-free method for fabricating high-performance silicon waveguides.
• This approach significantly reduces fabrication complexity and potential damage associated with etching.
• The demonstrated low losses (0.35 dB/cm) are promising for advanced integrated photonic circuits.