Modeling and analysis of distributed feedback quantum dot passively mode-locked lasers

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Quantum Dot Devices

Background:

• Quantum dot passively mode-locked lasers (QDMLLs) are crucial for ultrahigh-bit-rate and single-mode applications.
• Enhancing the performance of QDMLLs is essential for advancing optical communication technologies.

Purpose of the Study:

• To numerically investigate two monolithic distributed feedback quantum dot passively mode-locked lasers (DFB-QDMLLs).
• To compare DFB-QDMLLs with and without gratings in the saturable absorber (SA) section for enhanced performance.
• To analyze temporal and spectral behaviors for optimizing ultrahigh-bit-rate and single-mode applications.

Main Methods:

• Numerical investigation of two proposed DFB-QDMLL structures.
• Comparison of laser performance based on grating length in the saturable absorber section.
• Analysis of temporal and spectral characteristics under specified bias conditions and SA lengths.

Main Results:

• Both structures can generate optical pulses with durations of 3-8 ps at 2nd and 4th harmonics of cavity round-trip frequencies.
• DFB-QDMLLs produce higher peak power optical pulses compared to grating-embedded saturable absorber (GESA-DFB-QDMLL) structures.
• GESA-DFB-QDMLLs yield shorter pulses with narrower spectral bandwidths.
• DFB-QDMLLs exhibit a wider operating range of absorber voltages than the sensitive GESA-DFB-QDMLL structure.

Conclusions:

• The choice between DFB-QDMLLs and GESA-DFB-QDMLLs depends on specific application requirements for pulse duration, peak power, and operating voltage range.
• DFB-QDMLLs are suitable for applications prioritizing peak power and wider operational stability.
• GESA-DFB-QDMLLs are advantageous for applications requiring shorter pulses and narrower spectral bandwidths.