VCSEL-Based PAM-4 Links up to 62 Gbit/s Over OM3, OM4, and WB-MMF: Performance Comparison at 850 nm and 1050 nm

We present an analysis of pulse-amplitude modulation 4 (PAM) based multimode fiber (MMF) links using VCSELs at 850 and 1050 nm across a wide range of fiber profiles with effective modal bandwidth spanning from 2 to 10 GHz.km. We demonstrate speeds>51.56 Gbit/s over a set of standard OM3 and OM4 fibers with bit error rate (BER) < 10(-12) using pseudo random bit sequence 7, up to reaches of 150 m and BER < 2 x 10(-4) up to 300 m using 850 and 1050 nm VCSELs. Further, using a prototype wide band MMF (WB-MMF) that is specially designed to operate between a wide band of 850 and 1100 nm, we demonstrate transmission at 62 Gbit/s with BER< 10(-12) up to 100 m reach and back-to-back at 66 Gbit/s. Fiber penalties are extracted at BER similar to 10(-12) for the set of OM4, OM3, and the WB-MMF tested. Results are compared for 850 and 1050 nm links, providing insights into the advantages and challenges in deploying longer wavelengths for bitrates> 50 Gbit/s using PAM-4. We perform VCSEL characterization and through a comparison with our analytic link model, identify various link penalties including those due to the relative intensity noise and mode partition noise of the VCSEL.