Performances of Conventional SOAs Versus QD-SOA in 1530-nm Upstream Transmission of 40 Gb/s Access Network

SOA is the key device for burst-mode upstream transmission of 40 Gb/s access network to extend distance and increase users. We evaluate two conventional SOAs and our QD-SOA in networks, consisting of 20-km Single Mode Fiber (SMF) and splitters (1:8, 1:16 & 1:32). First, their characteristics are reported: 3-dB bandwidth & peak wavelength of Amplified Spontaneous Emission (ASE) spectra, gain, saturation output & input, and Noise Figure (NF). QD-SOA gives the lowest NF of 4.59 dB at –20-dBm input due to its highest Optical Signal to Noise Ratio (OSNR). It also has the fastest response time (70 ps) with less data pattern effect when operating in saturation region. Besides the measurement of Input Power Dynamic Range (IPDR) of 3 SOAs, their performances of single versus two-cascaded SOA transmissions are evaluated by Bit Error Rate (BER) in many combinations of SMF and splitters. In case of inserting 1:8 splitter between two-cascaded SOAs, the performance of 2
^nd
-stage QD-SOA has lower BERs than 2
^nd
-stage conventional SOA due to its higher saturation output and less pattern effect when operating at high input power. Finally, both experimental and computed BERs are plotted versus SOA's input to confirm the OSNR degradation and data pattern effect.