Modulation bandwidth enhanced self-injection locking laser with an external high-Q microring reflector

Area of Science:

• Photonics and Laser Technology
• Integrated Optics
• Optical Communications

Background:

• Self-injection locking (SIL) lasers offer stable, narrow linewidths but often have limited modulation bandwidth.
• Enhancing direct modulation bandwidth in lasers is crucial for high-speed optical communication systems.
• Integrated photonic devices, like microring resonators (MRRs), provide compact and efficient optical functionalities.

Purpose of the Study:

• To propose and demonstrate a hybrid laser architecture that enhances direct modulation bandwidth and narrows linewidth.
• To leverage the benefits of self-injection locking and integrated photonic technology for improved laser performance.
• To investigate the impact of microring resonator parameters on laser characteristics.

Main Methods:

• A commercial distributed feedback (DFB) laser was butt-coupled with an external high-Q silicon nitride microring resonator (MRR).
• The MRR was used to establish a strong self-injection locking state, inducing photon-photon resonance.
• Optimization of MRR parameters was performed to fine-tune the laser's performance.

Main Results:

• The hybrid laser demonstrated a direct modulation bandwidth enhancement to 15.28 GHz, a significant increase from the original 7.70 GHz.
• The laser linewidth was narrowed to 4 kHz, a substantial improvement from the initial 600 kHz.
• Stable single-mode output with a narrow linewidth was achieved due to the strong self-injection locking and photon-photon resonance.

Conclusions:

• The proposed hybrid laser design effectively enhances modulation bandwidth and narrows linewidth by combining DFB lasers with MRR.
• This integrated photonic approach offers a promising solution for high-speed and stable laser sources in optical communications.
• The developed technology capitalizes on the synergy between self-injection locking and silicon nitride microring resonators for advanced laser applications.