Timing jitter reduction in semiconductor lasers induced by optical injection.

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Laser Dynamics

Background:

• Gain-switched discrete-mode semiconductor lasers (DMLs) are crucial for high-speed optical communications.
• Timing jitter in DMLs limits their performance and necessitates mitigation strategies.
• Optical injection (OI) is a potential method for controlling laser dynamics.

Purpose of the Study:

• To experimentally investigate the impact of continuous-wave optical injection (OI) on the timing jitter of a gain-switched DML.
• To analyze the effect of varying temperature-tuned detuning between the DML and the injecting VCSEL on timing jitter.
• To compare OI-induced timing jitter with the intrinsic inter-pulse timing jitter of the DML.

Main Methods:

• Experimental setup involving a gain-switched DML and a continuous-wave VCSEL for optical injection.
• Temperature control of the DML to systematically vary the frequency detuning between the lasers.
• Measurement and analysis of timing jitter over a range of detunings and comparison with solitary DML jitter.

Main Results:

• A significant reduction in timing jitter, up to 70%, was observed for the DML under OI within a specific range of detunings.
• The effectiveness of jitter reduction was found to be highly sensitive to the precise detuning between the VCSEL and DML.
• Certain detuning values within the optimal range paradoxically led to a substantial increase in timing jitter.

Conclusions:

• Continuous-wave optical injection from a VCSEL offers a viable method for actively controlling and reducing timing jitter in gain-switched DMLs.
• Precise control over the frequency detuning is critical for successful jitter suppression, as suboptimal detuning can exacerbate jitter.
• This study highlights the complex interplay between optical injection parameters and laser jitter, offering insights for optimizing laser performance in high-speed systems.