Record-high 25.25-Gb/s real-time end-to-end optical orthogonal frequency-division multiplexing transmissions over an intensity-modulation and direct-detection-based 300-m OM2 multi-mode fiber links are achieved with a tri-sub-band transceiver architecture. A 9.75-Gb/s baseband signal is RF multiplexed with two 7.75-Gb/s sub-bands, which are IQ modulated onto a 6.125-GHz RF carrier. The adaptive bit/power-loaded, independently power-optimized sub-bands sampled at 4 GS/s are multiplexed to intensity modulate an EML. Similar BERs and <0.5-dB optical penalties are observed for all sub-bands.

Optical injection locking (OIL) is an effective approach for significantly enhancing the modulation bandwidths of VCSELs. The frequency responses of OIL-VCSELs are, however, very sensitive to the applied OIL conditions. This brings about strong difficulties in practically utilizing the OIL-enhanced modulation bandwidths to achieve highly robust transmission performances of directly modulated OIL-VCSEL-based multi-mode fibre (MMF) links for cost-sensitive application scenarios such as data-centers. In this paper, directly modulated OIL-VCSEL-based real-time dual-band optical OFDM (OOFDM) transceivers with tunability in both the electrical and optical domains are experimentally demonstrated, for the first time, utilizing DACs/ADCs at sampling speeds as low as 4GS/s. The transceivers can support 15.125 Gb/s adaptive OOFDM transmissions over 100 m OM2 MMF links based on intensity modulation and direct detection. More importantly, the adaptability and tunability of the demonstrated transceivers enable the achievement of excellent robustness of the aggregated OOFDM transmission capacity to OIL condition variations. It is shown that, over a large diversity of OIL conditions that give rise to significantly different system frequency responses, the aggregated OOFDM transmission capacity only vary by <11% in the aforementioned transmission link.

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