VCSEL for high-bit-optical access network

Development of optical access networks is driven by constant development of new applications and increased user’s requirements. This leads to increase in capacity that reaches few Gbps in optical access networks. This paper represents characteristics of a 1.55μm Vertical - Cavity Surface - Emitting Laser (VCSEL) transmitting on up to 20km distance with 1.25Gbps, 2.5Gbps and 10Gbps. VCSELs are widely deployed as optical sources in the optical access networks. Their main drawback is frequency variation of the currier, know as the chirp which manifests as a broadening of the optical spectrum ofthe signal. In this paper level of current when VCSEL starts to emit light is firstly determined. During its propagation the optical signal encounters two main effects degrading its quality - attenuation and dispersion. Attenuation reflects on extinction ratio. It is found that chirp can be used to diminish the effect of the dispersion cutting off lower frequencies energy. Also effects of BER are investigated for different distances. Results show that transmitting on 1.2 5Gbps and 2.5Gbps over 20km is with acceptable BER. Transmitting 10Gbps over 20 km shows that in order to have error - free transmission, it is needed to use forward error correction. Finally, results indicate benefits of implementation VCSELs in optical access networks. In conclusion, VCSELs have the potential to become a part of the next generation of optical access networks.