Thermal Effects and Small Signal Modulation of 1.3-μm InAs/GaAs Self-Assembled Quantum-Dot Lasers
1 School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Republic of Singapore
2 Photonics Group, Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 27 King's College Circle, Toronto, ON Canada
3 Institute of Solid State Physics, Technical University of Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
Nanoscale Res Lett 2011, 6:37 doi:10.1007/s11671-010-9798-4Published: 26 September 2010
We investigate the influence of thermal effects on the high-speed performance of 1.3-μm InAs/GaAs quantum-dot lasers in a wide temperature range (5–50°C). Ridge waveguide devices with 1.1 mm cavity length exhibit small signal modulation bandwidths of 7.51 GHz at 5°C and 3.98 GHz at 50°C. Temperature-dependent K-factor, differential gain, and gain compression factor are studied. While the intrinsic damping-limited modulation bandwidth is as high as 23 GHz, the actual modulation bandwidth is limited by carrier thermalization under continuous wave operation. Saturation of the resonance frequency was found to be the result of thermal reduction in the differential gain, which may originate from carrier thermalization.