Thermal Effects and Small Signal Modulation of 1.3-μm InAs/GaAs Self-Assembled Quantum-Dot Lasers.

Hx Zhao,Sf Yoon,Cy Liu,Cz Tong,R Wang,Q Cao

doi:10.1007/s11671-010-9798-4

Abstract

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.

Highlights

High-temperature stability in laser operation is an essential characteristic required for the long-wavelength semiconductor lasers in optical communication systems
We investigate the influence of thermal effects on the high-speed modulation characteristics of 1.3-μm InAs/GaAs QDs by studying the temperaturedependent small signal modulation behavior
The measured continuous wave (CW) Power-Current performance of a device with cavity length of 1.1 mm shows that the threshold current (Ith) and slope efficiency are 55 mA and 0.27 W/A at room temperature, respectively

Summary

Introduction

High-temperature stability in laser operation is an essential characteristic required for the long-wavelength semiconductor lasers in optical communication systems. This limits the modulation speed of QDs with deep confinement potentials such as the 1.3-μm InAs/GaAs QDs. Many theoretical [8,9] and experimental [3,10,11] investigations have been performed to study the bandwidth limitations in longwavelength QD lasers. K-factor [8,11] has been recognized to be one of the limiting factors for the modulation bandwidth of QD lasers, which accounts for the effect of photon lifetime, differential gain, and nonlinear gain compression factor.

Results

Conclusion