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 highcapacity
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 fiberoptic
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 fieldinstalled
fiber in an office building with environmentally exposed
roof-top link will be shown. On top of this, a zero-touch coexistence
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.