Automated measurement of optical coherence lengths and opticaldelays for applications in coherence-modulated opticaltransmissions

The implementation of an automated system for analysis of coherence length of light and for the measurement of optical delays is reported. This type of measurement is very important for designing coherence-modulated optical transmission systems. Such systems have been studied for the last few years as new potential high-speed optical links useful for point-to-point, local area networks, and bidirectional transmissions, at optical wavelengths around 1300 nm. The main characteristics of coherence-modulated transmissions include the need of using low-coherence optical sources and integrated optics lithium niobate (LiNbO₃) electro-optic retarders. This paper describes the implementation of an automated system allowing the measurement of coherence lengths of semiconductor optical sources and also optical delays as essential data for designing coherence-modulated optical links. The reported results include characterization of commercial low-coherence semiconductor optical sources and integrated optics coherence modulators