Effects of laser frequency chirp on modal noise in short-range radio over multimode fiber links.

An important effect of the frequency chirp of the optical transmitter in radio over multimode fiber links is put into evidence experimentally and modeled theoretically for the first time, to our knowledge. This effect can have an important impact in short-range connections, where, although intermodal dispersion does not generally cause unacceptable limitations to the transmittable bandwidth, the presence of modal noise must be accurately kept under control, since it determines undesired real-time fluctuations of the link.

Noise filtering in a multi-channel system using a tunable liquid crystal photonic bandgap fiber.

This paper reports on the first application of a liquid crystal infiltrated photonic bandgap fiber used as a tunable filter in an optical transmission system. The device allows low-cost amplified spontaneous emission (ASE) noise filtering and gain equalization with low insertion loss and broad tunability. System experiments show that the use of this filter increases for times the distance over which the optical signal-to-noise ratio (OSNR) is sufficient for error-free transmission with respect to the case in which no filtering is used.