  The digital transformation is creating basically a digital version of our
physical world and the currency in that digital space is data. Massive amount
of data has been generated ranging from wearable devices monitoring our
physical health every single millisecond to autonomous vehicles generating
roughly 5Tb hourly to even astronomical activities producing an order of
Exabytes on daily basis and then ultra-broadband Internet comes into play,
moving such data to the cloud. Internet traffic therefore has been experiencing
explosive growth and in this context, optical transport networks forming the
backbone of the Internet are pushed for transformation in system capacity.
While the intuitive solution of deploying multiple fibers can address the
pressing demand for increased capacity, doing so does not bring improvement in
economic of scales in terms of cost, power consumption and spectral efficiency.
This necessitates for a different approach so that the fiber capacity could be
utilized in a more efficient manner. In this paper, we focus on innovative
techniques, that is, photonic network coding and partial protection, to reduce
the effective traffic load in order to achieve greater capacity efficiency for
optical transport networks. Specifically, the application of network coding is
examined by upgrading the functionalities of intermediate nodes with
all-optical processing (i.e., encoding and decoding) capabilities. Besides,
partial protection relying on the premise of providing just enough bandwidth in
case of failure events is investigated for saving the redundant protection
capacity. That it takes two to tango, combining photonic network coding and
partial protection therefore bring to light new opportunities and challenges.
In mining such new avenue, we present insights on how to derive compounding
gains to maximize spectral efficiency via a case study.
