Mode-Locking and Noise Characteristics of InAs/InP Quantum Dash/Dot Lasers

• Published in: Journal of lightwave technology 2023-07, Vol.41 (13), p.4262-4270
• Main Authors: Liu, Guocheng, Poole, Philip J., Lu, Zhenguo, Liu, Jiaren, Song, Chun-Ying, Mao, Youxin, Barrios, Pedro
• Format: Article
• Language: English
• Subjects: Coherent comb lasers; coherent Terabit/s networking systems; Frequency stability; Indium arsenides; Indium phosphides; integrated optics devices; Laser mode locking; Lasers; Measurement by laser beam; Mode locking; Noise intensity; Optical pulses; quantum dash; Quantum dot lasers; quantum dot semiconductor mode-locked lasers; Quantum dots; Quantum efficiency; Radio frequency; Relative intensity noise; Repetition; Semiconductor lasers; Structural design; Threshold currents; Waveguide lasers
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2023.3244777

The mode-locking and noise characteristics of InP/InAs quantum dash (QDash) and quantum dot (QDot) multi-wavelength lasers, showing identical structural design, operating at the C -band, are investigated and compared to each other. The QDash lasers exhibit improved repetition frequency stability with a lower threshold current and cavity loss. On the other hand, the QDot lasers show higher quality repetition frequency tunability with higher internal quantum efficiency, as well as lower average integrated relative intensity noise (RIN) and average optical linewidth. Furthermore, we demonstrate both the QDash and QDot lasers exhibit very clean constellation diagrams at 32 GBaud 16QAM base-band signal, while the QDot lasers' bit-error ratio (BER) performance outperforms the QDashes. This finding highlights the viability of InAs/InP QDash/QDot lasers to be used as a low-cost optical source for large-scale networks.