Continuously tunable silicon optical true-time delay lines with a large delay tuning range and a low delay...

Area of Science:

• Photonics and Optical Engineering
• Integrated Optics
• Signal Processing

Background:

• On-chip optical true-time delay lines (OTTDLs) are crucial for applications like phased array antennas.
• Existing OTTDLs often have discrete tuning steps, limiting their precision and applicability.
• A continuous tuning capability with a large delay range is highly desirable for advanced optical systems.

Purpose of the Study:

• To propose and demonstrate a silicon-based broadband continuously tunable OTTDL.
• To achieve a large group delay tuning range with high precision.
• To develop a simplified calibration method for integrated OTTDLs.

Main Methods:

• Integration of a 7-bit delay line with a switch-based continuously tunable delay line on a silicon platform.
• Experimental characterization of the group delay tuning range, delay error, and delay fluctuation.
• Analysis of delay fluctuation causes and its impact on beamforming.
• Development and validation of a simplified non-invasive calibration method.

Main Results:

• Demonstration of a continuously tunable OTTDL with a group delay range from 0 to 1020.16 ps.
• Achieved delay error within -1.27 ps to 1.75 ps.
• Observed delay fluctuation below 2.69 ps across a 2–25 GHz frequency range.
• Successful proposal and analysis of a simplified calibration technique.

Conclusions:

• The proposed silicon-based continuously tunable OTTDL achieves a significant delay tuning range and high precision.
• The developed calibration method simplifies the process and is scalable for complex systems.
• The high performance of the chip and calibration method pave the way for practical applications of integrated OTTDLs.