Experimental demonstration and performance evaluation of flexible add/drop operations of DSP-switched ROADMs for cloud access networks

• Published in: Optics communications 2018-12, Vol.428, p.95-103
• Main Authors: Deng, M.L., Duan, X., Jin, W., Giddings, R.P., Mansoor, S., Tang, J.M.
• Format: Article
• Language: English
• Subjects: Digital orthogonal filtering; Digital signal processing (DSP); Intensity modulation; Reconfigurable optical add/drop multiplexer (ROADM)
• ISSN: 0030-4018; 1873-0310
• DOI: 10.1016/j.optcom.2018.07.050

Making use of Hilbert-pair-based digital filtering, intensity modulation and passive optical coupling, optical filter- and O-E-O conversion-free flexible ROADMs are, for the first time, experimentally demonstrated to perform DSP-enabled dynamic add/drop operations at wavelength, sub-wavelength and spectrally overlapped sub-band levels. Extensive experimental explorations of physical-layer add/drop operation performances and their robustness to variations in both differential optical power dynamic range and drop RF signal power are also undertaken in IMDD-based optical network nodes. It is shown that the ROADM add/drop operation performances are independent of the sub-band spectral location, and that the add/drop operations introduce optical power penalties of ≤ 1.8 dB. In addition, for a total optical power as low as −12 dBm, the add operation still can tolerate a differential optical power dynamic range of > 2 dB. Whilst for the drop operation, an optical power penalty of < 2 dB is observed over a drop RF signal power variation range of 7.1 dB. Experimental results indicate that the add/drop operations of DSP-switched ROADMs have excellent performance robustness to considerably relax stringent requirements on network components.