Wideband FTTR PON for Joint Wired and Shortwave Optical Wireless Access

As access to symmetric 10⁺ Gb/s data rates through Passive Optical Network (PON) standards becomes widely available, the support for a bandwidth continuum calls for natural in-house extensions such a Fiber-to-the-Room (FTTR). At the same time, optical wireless communication (OWC) and visible light communication (VLC) can assist the delivery of multi-Gb/s data rates to mobile users when paired with a high-capacity fiber fronthaul. Towards this direction, optical wireless access can greatly benefit from the deployment of FTTR but has to overcome technological roadblocks when operation in the shortwave band at 850 nm and below shall be considered. The implications due to few-mode shortwave propagation over an FTTR PON furnished with standard telecom fiber and fiber-optic splitters designed for near-infrared O- to L-band operation will be studied, including the transmission of VLC channels operating at short wavelengths as low as 494 nm. Bandwidth limitations due to differential mode delay and speckle-selective loss in widely deployed near-infrared power splitters will be investigated and a simple mode coupling control will be proposed and adopted as a mitigation technique. OWC and VLC data rates of 15 and 4 Gb/s will be demonstrated over a 1 × 8 split FTTR PON and the long-term stability of VLC transmission over field-installed fiber in an office building with environmentally exposed roof-top link will be shown. On top of this, a zero-touch co-existence strategy for wired-wireline integration in a filterless PON architecture will be proven through demonstration of OWC-blind FTTR transmission – even under a high dynamic power ratio of +10 dB towards favoring the OWC channel.