Optimised non-uniform biasing technique for a high-speed optical router to achieve uniform semiconductor optical amplifier gain

A numerical assessment of an effective envelope-tracking semiconductor optical amplifier design for coherent-optical OFDM transmission

“…Different techniques have been reported so far, with various cases depending on the role of the SOA (booster, in-line amplifier or pre-amplifier, with possible cascade) and on the number of channels involved. Some techniques alleviate the nonlinear distortions via digital signal processing like digital backpropagation [13] [14] or digital predistortion [15] [16], and non-DSP schemes have also been investigated, like feedforward linearization [17], gain-clamped SOA [18] and non-uniform biasing [20,19]. Other efforts have focused on changing the device design, either with multi-contact SOA [21] or Quantum-Dot structure [22].…”

“…Around 14 dB reduction in the intermodulation distortion over a wide range of input power has been reported in this work, for a frequency separation going up to 1.25 GHz between the two tones. Later, Ng et al [20] proposed an optimized non-uniform bias current so as to achieve SOA gain uniformity in presence of high speed input pulses. In a recent work, Fujiwara and Koma [26] proposed to vary the SOA bias current to cope with the near-far problem typical of PON upstream transmission.…”