Vertical cavity surface emiting laser for optical communication systems

Abstract

The minimal cost, high efficiency and low power consumption of the Vertical Cavity Surface Emitting Laser (VCSEL) gives it an additional advantage when used in applications like fibre optical communication systems to meet the growth of data communication traffic. However, development of VCSELs working at longer wave lengths (1.3- 1.55 µm) has been limited by the inherent material problem making VCSELs longitudinal single-modes emitters. These problems among commonly used fibre optic transmitters (Light Emitting Diodes) include: limited efficiency, limited power output and incoherent light. Emitted power, threshold current and voltage are the main device characteristics studied in this research. The basic functionality of semiconductor lasers with improved output power performance is the main aim of this work. Comparisons of growth techniques and material selection gives the best material performance for nano optical sources used in optical communication systems. A seven Quantum Well Indium Gallium Arsenide Phosphide (InGaAsP) VCSEL structure that emits at 1550 nm is simulated and the following characteristics are analysed: Direct current and voltage (I-V) characteristics, light power against electrical bias, optical gain against electrical bias, light distribution over the structure, output power, threshold current and gain profiles. The specification of the material characteristics, the ordinary physical model settings, the initial VCSEL biasing, the mesh declarations, declaration of laser physical models, their optical and electrical parameters were defined using Atlas syntax. Mirror ratings and Quantum Wells are the two main parameters that were studied and analysed. Proper selection of the emission wavelength and choice of material was done and a VCSEL with an output power of 9.5 mW was simulated and compared with other structures.