Experimental Demonstration of Soft-ROADMs With Dual-Arm Drop Elements for Future Optical-Wireless Converged Access Networks

• DOI: 10.1109/jlt.2023.3328771
• Publication Date: 2023-10-30T19:14:23Z
• Authors: Omaro Fawzi Abdel...; Roger Philip Gidd...; Jianming Tang
• Keywords: Optical add-drop multiplexer; Optical cross-connect

Digital signal processing (DSP)-enabled soft reconfigurable optical add/drop multiplexers (Soft-ROADMs) offer flexible switching at wavelength, sub-wavelength and spectrally-overlapped orthogonal (I Q) sub-band (SB) levels, which makes them highly desirable for enabling optical-wireless converged access networks where both fixed wireless services are consolidated in a shared network, network resource efficient cost-effective connectivity solutions. However, the performance of targeted (TSB) extracted by soft-ROADM drop element is extremely sensitive to RF phase offset, major limitation impacting technical feasibility soft-ROADMs. To overcome this challenge, paper, phase-offset-insensitive dual-arm IQ operation proposed experimentally demonstrated. A DSP implemented multi-input multi-output (MIMO)-based I/Q crosstalk mitigation technique employed achieve insensitivity offset. It shown that, traditional single-arm has limited offset dynamic range <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim \pm \,\pi /4$</tex-math></inline-formula> ( notation="LaTeX">$ &lt; \,0.05\pi $</tex-math></inline-formula> ) presence (I&Q) SBs, thus requiring accurate control, however, demonstrates ability tolerate any arbitrary completely eliminating need dynamically control signal's phase. This paper also effectiveness new mitigate effects caused by, various effects, including fiber transmission channel-induced frequency response roll-off, symbol timing propagation delay drifting effects. Importantly, it that offers poor stability as dropped TSB's BER degrades within few minutes, whereas, achieves stable performance. Soft-ROADMs incorporating newly significantly reduced implementation complexity, radically increasing their suitability application networks.