Reconfigurable monitoring and control system for tunable optical delay lines

Area of Science:

• Photonics
• Optical Engineering
• Integrated Optics

Background:

• Tunable optical delay lines (TODLs) are crucial components in optical systems.
• Existing TODL control methods can be complex and technology-dependent.
• Scalable and versatile control systems are needed for advanced photonic applications.

Purpose of the Study:

• To propose a universal monitoring and control system (MCS) for TODLs.
• To enable precise delay tuning irrespective of the TODL's operational principle or implementation.
• To demonstrate the MCS's applicability across different silicon photonic integrated circuits (PICs).

Main Methods:

• The MCS utilizes two out-of-band pilot tones added to the input optical signal.
• Amplitude and phase differences of the pilot tones are measured.
• A control system calculates and applies necessary adjustments to the TODL.

Main Results:

• The MCS was successfully validated on a Mach-Zehnder delay interferometer-based TODL.
• Testing was performed on three silicon PICs featuring thermo-optic, carrier-injection, and carrier-depletion phase shifters.
• The proposed MCS achieved full-range delay tuning for all tested TODLs.

Conclusions:

• The developed MCS offers a versatile and effective solution for controlling TODLs.
• The system demonstrates robustness across diverse phase-shifting technologies in silicon photonics.
• The MCS shows promise for scalability in large-scale photonic beamforming applications.