Analysis of TDEC Pattern Dependency for 50G-PON Optical Transmitter Characterization

The Transmitter Dispersion Eye closure (TDEC) can evaluate the quality of an optical transmitter. Initially introduced by the IEEE and later adapted by the ITU-T, TDEC is an economical experimental technique based on eye diagram characterization, using standard optical receiver. For TDEC compliance with the 50G-PON ITU-T recommendation, it is mandatory to use the reference transmitted bit pattern sequence called “Short Stressed Pattern Random” (SSPR). The SSPR pattern test may be difficult to implement for telecommunications operators, because they generally cannot connect an optical transmitter to transmission equipment that generates a specific sequence. In this Letter, we thus analyze the TDEC dependency on the transmitted bit pattern sequences, by means of experimental demonstrations and simulations (to emulate two other different transmitters), in order to identify which bit pattern sequences may be used to better approximate the correct TDEC. In the experimental case, for every sequence under test, we present the corresponding estimated TDEC value and its statistical analysis over 10 acquisitions. Finally, we explore the clock recovery impact on the TDEC.