Self-amplified transceivers for local-access star networks

We describe a cost-effective approach to fiber-amplified networks based on dual use of lasers and other components for both signal and pump functions. The concept is demonstrated in a broadband, passive star network suitable for local access applications, using bidirectional transmission on a single fiber. Sensitivity improvement of 8.2 dB is achieved in the downlinks operating at 1.55-μm wavelength, while uplinks at 1.48 μm provide both pump and data. A model for receiver sensitivity incorporating the effects of spontaneous emission noise is used to explain the effect of optical filtering and to assess the potential for further improvement.