Lee S.-YCheng C.-HHuang K.-YChen XLi KWang C.-HLi M.-JCHAO-HSIN WULin G.-R.2023-06-092023-06-09202210944087https://www.scopus.com/inward/record.uri?eid=2-s2.0-85129612892&doi=10.1364%2fOE.455379&partnerID=40&md5=05e56c2013bd869b2121666ed5fe08f7https://scholars.lib.ntu.edu.tw/handle/123456789/632219By collimating the single-mode (SM) vertical-cavity surface-emitting laser (VCSEL) at 850 nm with either the OM4 multi-mode fiber (OM4-MMF) or the graded-index single-mode fiber (GI-SMF) with lensed end-face, the directly encoded non-return-to-zero on-off keying (NRZ-OOK) data transmission performance is characterized when tilting the coupling angle with respect to the surface normal of the SM-VCSEL. In comparison with the lensed OM4-MMF and lensed SMF coupling, the lensed OM4-MMF collimator shows a large coupling angle tolerance with the coupling efficiency only degraded by 5% when enlarging the tilted angle from 0° to 10°. In contrast, the lensed GI-SMF collimator attenuates the coupled SM-VCSEL output by more than 50% when tilting the coupling angle up to 10°. For the lensed OM4-MMF coupling, the receivable NRZ-OOK data rate in BtB and after 100-m OM4-MMF cases can achieve 50 Gbit/s with its corresponding BER degraded from 6.5 ? 10-10 to 8.8 ? 10-10 when enlarging its tilting angle ranged from 0° to 10°. By changing the collimator to the lensed SMF, the decoded BER significantly degrades from 5.8 ? 10-5 to 1.2 ? 10-1 when coupling and transmitting the NRZ-OOK data at 50 Gbit/s. Owing to the low coupling efficiency via the lensed SMF collimator, the error-free NRZ-OOK data rate under the lensed SMF coupling somewhat decreases to 35 Gbit/s in the BtB link and to 32 Gbit/s after the 100-m GI-SMF link with allowable coupling angle tilted from 0° to 4°. This work confirms the applicability of the lensed MMF or SMF collimator for coupling the SM-VCSEL output with a relatively large tolerance on the tilting angle with respect to the surface normal of the SM-VCSEL. © 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing AgreementAmplitude shift keying; Efficiency; Surface emitting lasers; Coupling angles; Coupling efficiency; Data-rate; Fiber collimators; Graded index; Non-return-to-zero; On/off-keying; Single mode; Single-mode fibers; Surface normals; Single mode fibersjournal article10.1364/OE.4553792-s2.0-85129612892