Clock recovery using cascaded LiNbO3 modulator.

Area of Science:

• Optical Communications
• Signal Processing
• Integrated Photonics

Background:

• High-speed optical data transmission demands precise clock recovery for signal integrity.
• Existing clock recovery methods face challenges with complex data patterns and high bit rates.

Purpose of the Study:

• To demonstrate effective clock recovery from a patterned optical-time-division-multiplexed (OTDM) return-to-zero (RZ) data stream.
• To achieve high-precision clock extraction at 10GHz from a 160Gb/s signal.

Main Methods:

• Utilized a cascaded Lithium Niobate (LiNbO3) Mach-Zehnder modulator as an optical-electrical mixer.
• Employed a phase-locked loop (PLL) to synchronize a local oscillator to the optical data stream's clock component.
• Analyzed the cross-correlation between the optical signal and the local oscillating signal.

Main Results:

• Successfully extracted a 10GHz clock signal from a 160Gb/s optical TDM signal.
• Achieved a measured root-mean-square (RMS) timing jitter of approximately 130 femtoseconds (fs) for the recovered clock signal.
• Demonstrated the efficiency of the cascaded LiNbO3 Mach-Zehnder modulator in optical-electrical mixing.

Conclusions:

• The proposed method enables robust clock recovery from complex, high-speed optical data streams.
• The employed optical-electrical mixer and PLL offer a viable solution for precise clock signal extraction in optical networks.
• The low timing jitter achieved is critical for future high-capacity optical communication systems.