A terabit-per-second all-optical four-bit digital-to-analog converter using quantum dot semiconductor optical amplifiers

An all-optical digital-to-analog converter (DAC) using quantum dot semiconductor optical amplifiers (QDSOAs) is proposed and analyzed. The device operates at low optical power (~ 0.5 mW) at a speed of 1 Tbps. The resolution of the DAC is four bits, and the corresponding step size is 1.068 mW (compared with the ideal value of 1 mW). The dynamic range is found to be 11.47 dB (versus the ideal value of 11.76 dB). The average absolute error for all the states of the proposed optical DAC is 0.53%, with a maximum error of 1.85%, being the first time that such performance has been achieved to the best of the authors’ knowledge. It is shown that the amplified spontaneous emission (ASE) noise has no significant effect on the performance of the DAC.