TY - JOUR
T1 - Experimental Demonstration of 84 Gb/s PAM-4 Over up to 1.6 km SSMF Using a 20-GHz VCSEL at 1525 nm
AU - Eiselt, Nicklas
AU - Griesser, Helmut
AU - Wei, Jinlong
AU - Hohenleitner, Robert
AU - Dochhan, Annika
AU - Ortsiefer, Markus
AU - Eiselt, Michael H.
AU - Neumeyr, Christian
AU - Vegas Olmos, Juan José
AU - Tafur Monroy, Idelfonso
PY - 2017
Y1 - 2017
N2 - We demonstrate 84-Gb/s four-level pulse amplitude modulation (PAM-4) over up to 1.6-km standard single mode fiber using a 20-GHz single mode short cavity vertical cavity surface emitting laser diode at a transmission wavelength of 1525 nm. Different equalizer approaches including a common feedforward equalizer, a nonlinear Volterra equalizer (NLVE), a maximum likelihood sequence estimator (MLSE) and their combinations are evaluated working either as an equalizer for a standard PAM-4 or a partial response PAM-4 signal with seven levels. It is demonstrated that a standard FFE is not enough for a transmission distance of >0.6 km, while the use of an NLVE or FFE + MLSE is able to improve the transmission distance towards 1 km. The use of partial-response PAM-4 FFE in combination with a short memory MLSE is able to efficiently equalize the bandwidth limitations, showing more than 10-times BER improvement compared to standard NLVE or FFE + MLSE at a transmission distance of 1.6 km. Using a partial-response NLVE instead of an PR-FFE further performance improvement is achieved, resulting in BERs below the KP4 FEC-threshold with a BER-limit of 2E-4 after 1.6-km transmission distance, allowing error free operation.
AB - We demonstrate 84-Gb/s four-level pulse amplitude modulation (PAM-4) over up to 1.6-km standard single mode fiber using a 20-GHz single mode short cavity vertical cavity surface emitting laser diode at a transmission wavelength of 1525 nm. Different equalizer approaches including a common feedforward equalizer, a nonlinear Volterra equalizer (NLVE), a maximum likelihood sequence estimator (MLSE) and their combinations are evaluated working either as an equalizer for a standard PAM-4 or a partial response PAM-4 signal with seven levels. It is demonstrated that a standard FFE is not enough for a transmission distance of >0.6 km, while the use of an NLVE or FFE + MLSE is able to improve the transmission distance towards 1 km. The use of partial-response PAM-4 FFE in combination with a short memory MLSE is able to efficiently equalize the bandwidth limitations, showing more than 10-times BER improvement compared to standard NLVE or FFE + MLSE at a transmission distance of 1.6 km. Using a partial-response NLVE instead of an PR-FFE further performance improvement is achieved, resulting in BERs below the KP4 FEC-threshold with a BER-limit of 2E-4 after 1.6-km transmission distance, allowing error free operation.
KW - Adaptive equalizers
KW - Digital signal processing
KW - Nonlinear estimation
KW - Optical fiber communication
KW - Pulse amplitude modulation
KW - Vertical cavity surface emitting lasers
U2 - 10.1109/JLT.2017.2662800
DO - 10.1109/JLT.2017.2662800
M3 - Journal article
SN - 0733-8724
VL - 35
SP - 1342
EP - 1349
JO - Journal of Lightwave Technology
JF - Journal of Lightwave Technology
IS - 8
ER -