Measurements, analysis and modeling of the performance of direct detection receivers with an optical preamplifier
Butaney, Vikas Hari
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In the last few years, erbium-doped fiber amplifiers (EDFAs) have been investigated extensively both for their superior amplification characteristics and their applicability to future optical fiber communication systems. In the preamplifier configuration, a bandpass filter is required to reduce the amplified spontaneous emission (ASE) noise in order to provide satisfactory bit error ratios (BER). In this thesis we examine the influence of the filter characteristics on performance. A model is derived to predict the BER performance of a pre-amplified APD receiver. The model is shown to be consistent with the experiments conducted at 2.5 Gb/s and data collected for various bandwidths and signal levels. The model is also compared with a recently published model, and the results show a good match. If the bandpass filter (BPF) has a small bandwidth and the laser center wavelength varies, the filter will attenuate the signal and introduce power penalties. The tradeoff between the stability of the system and the BER performance is presented, including experimental results for various bandwidths and offsets. It is shown that for optimal performance, a filter with a bandwidth about four times the expected variation in center wavelength should be used.
- Masters Theses