Impact of Damping on High-Speed Large Signal VCSEL Dynamics

• Published in: Journal of lightwave technology Vol. 33; no. 4; pp. 795 - 801
• Main Authors: Haglund, Emanuel P., Westbergh, Petter, Gustavsson, Johan S., Larsson, Anders
• Format: Journal Article
• Language: English
• Published: IEEE 15-02-2015
• Subjects: Bandwidth; Damping; high-speed modulation; large signal modulation; Modulation; Optical attenuators; Oscillators; photon lifetime; relaxation oscillation; semiconductor lasers; Timing jitter; Vertical cavity surface emitting lasers; vertical cavity surface-emitting laser (VCSEL); Damping; relaxation oscillation; photon lifetime; semiconductor lasers; large signal modulation; high-speed modulation; vertical-cavity surface-emitting laser (VCSEL)
• ISSN: 0733-8724; 1558-2213; 1558-2213
• DOI: 10.1109/JLT.2014.2364455

An investigation of the optimal relaxation oscillation damping for high-speed 850-nm vertical-cavity surface-emitting laser (VCSEL) under large signal operation is presented, using devices with K -factors ranging from 0.1 to 0.4 ns. Time-domain measurements of turn-on transients are used to quantify damping dependent rise times, overshoots, and signal amplitudes. Optical eye diagrams together with timing jitter and bit error rate measurements reveal a tradeoff between the rise time and the duration of the relaxation oscillations. To produce a high-quality eye at a specific data rate, a proper amount of damping is needed to simultaneously obtain sufficiently high bandwidth and low timing jitter. We found that for error-free transmission, a VCSEL with a 0.3 ns K-factor achieved the best receiver sensitivity at 10 and 25 Gb/s, whereas a less damped VCSEL with a 0.2 ns K-factor achieved the best sensitivity at 40 Gb/s.