Continuously tunable reflective-type optical delay lines using microring resonators.

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Optical Communications

Background:

• Optical delay lines are crucial components in high-speed optical signal processing and buffering.
• Existing designs face limitations in delay-bandwidth product and tunability.
• Microring resonators offer a promising platform for compact and reconfigurable photonic devices.

Purpose of the Study:

• To develop a reflective-type optical delay line with an enhanced delay-bandwidth product.
• To demonstrate continuous tunability of group delay using integrated microheaters.
• To evaluate the buffering capacity and performance of the proposed optical delay line.

Main Methods:

• Utilized a waveguide side-coupled sequence of 13 microring resonators.
• Incorporated a Sagnac loop reflector for a reflective-type configuration.
• Integrated p-i-p type microheaters for group delay tuning.
• Tested with a 20-Gbps pseudo-random binary sequence (PRBS) signal.

Main Results:

• Achieved a doubled delay-bandwidth product due to light traversing the resonator sequence twice.
• Demonstrated continuous delay tuning over 100 ps with a power tuning efficiency of 0.34 ps/mW.
• Showcased potential for buffering up to 18 bits.
• Examined eye diagrams for 20-Gbps PRBS signals at 10 ps and 110 ps delays.

Conclusions:

• The presented reflective optical delay line offers significant improvements in delay-bandwidth product.
• Integrated microheaters provide efficient and continuous tunability of optical delay.
• The device shows promise for high-speed optical buffering applications in future communication systems.