Fiber transmission systems with semiconductor optical amplifiers without in-line filtering

10 Gbit/s RZ signal transmission at 1.3 m in a fiber transmission system with in-line semiconductor optical amplifiers is investigated using a recirculating fiber loop setup. We found that under certain conditions the system operates without in-line filtering and with strongly saturated amplifiers, provided the signal is extracted from the amplified spontaneous emission by means of a narrow optical filter in front of the receiver. These results are compared with a transmission scheme with in-line filtering.