Fiber optic duplexer

Abstract

In traditional optical communication, duplexity is achieved by using two fibers, each having a transmitter and a receiver. Economically, bidirectional wavelength division multiplexing (WDM) transmission systems utilizing a single fiber will be more attractive not only reducing the use of the fiber by a factor of two, but also the number of components. Duplex transmissions over a single fiber can double the capacity of an installed unidirectional link. Optical fiber duplexer was implemented in this work, where two signals were carried over a single fiber. The interband and intraband crosstalk were modeled and analyzed. It was found that the intraband crosstalk did not affect the received signal as long as it is below -25dB. Increasing this value caused the power penalty to increase. The power penalty when the spontaneous beat noise of the received signal dominates was calculated. Calculation was also made in the case when the noise is dominated by thermal noise. It was found that the power penalty is worst for the thermal noise dominated case. From the experimental results, it was found that the minimum crosstalk was -39dB and the corresponding power penalty was 0.1513dBm. The case worsened when more than three signals had same wavelength, the gain band between the channels to be transmitted should be according to the ITU-T standards to prevent crosstalk from occurring