Influence of Mode $Q$ Factor and Absorption Loss on Dynamical Characteristics for Semiconductor Microcavity Lasers by Rate Equation Analysis

Dynamical characteristics of microcavity lasers are investigated by small signal analysis and large signal simulation based on single-mode rate equations, emphasized on the influence of the mode quality factor (Q factor) of the passive cavity and the internal absorption loss. The results indicate that a large 3-dB bandwidth does not always accompany a high quality eye diagram, especially for the small signal modulation with a high resonance peak. High Q factor and low internal loss are both required for high speed operation at a low biasing current. For a 2.5-μ.m-radius microcircular laser with an internal absorption loss α_i = 1 cm^-1 and a cavity Q factor of 7 × 10⁴, high-quality eye diagrams are realized at a modulation rate of 10 Gb/s under a biasing current of twice the threshold current. The results show the broad prospects for the directly modulated microcavity lasers as a low-power efficient light source in on-chip optical interconnection.