Ultra-low loss optical delay lines based on silicon nitride SWG technology

Area of Science:

• Photonics
• Materials Science
• Integrated Optics

Background:

• Optical delay lines are critical components in microwave photonics and optical signal processing.
• Existing silicon-based solutions face limitations in insertion loss and compactness.

Purpose of the Study:

• To design, optimize, and demonstrate compact optical delay lines.
• To leverage silicon nitride and subwavelength grating (SWG) structures for improved performance.

Main Methods:

• Utilized silicon nitride platform for low-loss waveguides.
• Designed and optimized SWG tapers and bends.
• Fabricated and characterized optical delay lines.

Main Results:

• Achieved low loss for SWG tapers (0.04 dB) and bends (0.82 dB).
• Demonstrated a tunable group delay by adjusting the SWG duty cycle.
• Fabricated delay lines exhibit 1.6 dB/cm loss, outperforming silicon-based devices.

Conclusions:

• Silicon nitride SWG structures enable high-performance, compact optical delay lines.
• The tunable delay mechanism offers flexibility for photonic integrated circuits.
• This technology presents a promising alternative for advanced optical signal processing.