Aggregated 17.125 Gb/s real-time end-to-end dual-band optical OFDM (OOFDM) transmissions over 25 km SSMF IMDD systems with 7 dB receiver sensitivity improvements are experimentally demonstrated, for the first time, by utilizing low-cost transceiver components such as directly modulated 1GHz RSOAs and DACs/ADCs operating at sampling speeds as low as 4GS/s. The demonstrated OOFDM transceivers have both strong adaptability and sufficiently large passband carrier frequency tunability, which enable full use of highly dynamic spectral characteristics of the transmission systems. This results in the achievements of not only excellent performance robustness to variations in system operating conditions but also significantly relaxed requirements on RSOA small-signal modulation bandwidth. It is shown that the aforementioned transmission capacity only varies by <23% over a RSOA-injected optical power variation range as large as 20dB, and that the 1 GHz RSOAs can support successful transmissions of adaptively modulated OOFDM signals having bandwidths of 8.5 GHz. By taking into account the adopted 25% cyclic prefix and a typical 7.3% FEC overhead, the demonstrated real-time OOFDM transmission systems are capable of conveying 11.6 Gb/s user data.

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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