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

Abstract

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.

Performance Investigations of InAs/InP Quantum-Dash Semiconductor Optical Amplifiers with Different Numbers of Dash Layers

“…An optical signal-noise ratio (OSNR) of 39.9 dB and NF of 5.7 dB were achieved, while an OSNR of 34.3 dB and NF of 4.8 dB were reported in Ref. [23] with very similar measurement conditions; however, their NF was calculated without considering the polarization effect on the SOA compared with our measurement using PM fiber. Therefore, a correction factor of 2 is needed in their NF result.…”

“…A record high chip gain of 35 dB at 400 mA from an InAs/InP QD SOA was reported, with a 1% bias duty cycle and 15 dB coupling loss/facet [22]; however, the chip gain calculation method they used based on calibration of the very large coupling loss and extremely small duty cycle was not convincing. In a following publication from the same group [23], a lower NF of 4.59 dB at an input of -20 dBm and 400 mA from an InAs/InP QD SOA was reported. We believe that this value of NF should actually be multiplied by a factor 2, because the equation used to calculate NF (Equation (2) in Ref.…”

“…To compare the performance of our InAs/InP Qdash SOA with the InAs/InP Qdot SOA reported in Ref. [23], spectra of the input tunable laser source and output signal of our Qdash SOA were measured under the conditions of −20 dBm input power, 1532 nm wavelength, 300 mA bias current, and 25 • C temperature, as shown in Figure 7c. An optical signal-noise ratio (OSNR) of 39.9 dB and NF of 5.7 dB were achieved, while an OSNR of 34.3 dB and NF of 4.8 dB were reported in Ref.…”

“…The study of QD SOAs and their applications have developed quickly in recent years [12][13][14][15][16][17][18][19][20][21][22][23]. QD-SOAs are excellent candidates for high-speed optical and wireless transmission applications due to their ultrafast gain dynamics and pattern effect-free amplification [2,3,12].…”

“…We believe that this value of NF should actually be multiplied by a factor 2, because the equation used to calculate NF (Equation (2) in Ref. [23]) did not consider the very important polarization properties of SOA.…”