A BACK REFLECTION OPTICAL SIGNAL DETECTION-BASED
AUTOMATIC WAVELENGTH ALLOCATION METHOD FOR
CHANNEL-REUSE DWDM-PON WITH TUNABLE LASERS
Xu Jiang, Zhiguo Zhang, Jiahe Wang, Xue Chen
State Key Lab of Information Photonics and Optical Communications
Beijing University of Posts and Telecommunications, Beijing 100876, China
zhangzhiguo@bupt.edu.cn
ABSTRACT
We demonstrate a back reflection optical signal
detection-based automatic wavelength control method for
channel-reuse, DWDM-PON. A 40-km-reach,
channel-reuse, full-duplex, bidirectional 10 Gb/s
transmission on a 50 GHz WDM grid is achieved.
Keywords: wavelength division multiplexing passive
optical network, channel-reuse, tunable laser, automatic
wavelength control
1. INTRODUCTION
Wavelength division multiplexing passive optical
network (WDM-PON) has been regarded as a promising
solution for next-generation optical access networks with
needs of high security, easy maintenance, great
flexibility, as well as broad bandwidth [1, 2]. Driven by
ever-increasing users’ demands for broad-band services
to support high quality IPTV, e-learning, interactive
games, future looking peer-to-peer multimedia services
and remote base station services, it is expected that the
data rate demand will continuously grow and numerous
access nodes will be deployed over the next decades [3].
As the cost-effectiveness characteristics of WDM-PON
make it difficult to achieve high bit rate for each
wavelength, improving the spectral efficiency is a
promising method to enhance the system capacity [4].
Narrow channel spacing and channel reuse techniques
are promising solutions to increase the total system
capacity of 10-Gb/s per channel WDM-PON.
To achieve the cost-effectiveness characteristics of
WDM-PON, the low noise cost-effective colorless or
color-free optical source is one of the important issues
and a tunable laser has been investigated as a promising
optical source for a very high-speed WDM-PON
[5].However, an automatic wavelength control method is
needed to realize true color-free operation with plug and
play feature. To solve this problem, a self-wavelength
tracking method that monitors the wavelength with
maximum power of back scattering in the transmission
fiber was proposed, however its control accuracy is
degraded as length of drop fiber increases [6].
In this paper, we propose an automatic wavelength
control method to provide plug and play feature in
bidirectional 10-Gb/s/λ channel-reuse dense WDM PON
(DWDM-PON). Compared to the method in [6], the
proposed architecture avoids the reception of back
scattering of drop fiber, and to ensure a detectable and
reliable received optical power, a reflecting device which
consists of a 95:5 optical couple and an optical cycle
loop is used. As the reflecting device may bring
additional noise to downstream signal, we measure the
BER performances of the downstream with and without
the device. The additional noise could be regarded as
enhanced Rayleigh backscattering as it is a back
reflection of upstream optical signal. Since wavelength
shifts (WS) between upstream wavelength and
downstream wavelength in channel-reuse DWDM-PON
can well eliminate the back scattering noise effects [7],
the penalty induced by the additional noise in our system
is measured less than 0.5dBm. 50-GHz channel spacing
30km feeder fiber and 10km drop fiber bidirectional
10-Gb/s/λ transmission are demonstrated.
2. SYSTEM ARCHITECTURE AND
WAVELENGTH MANAGEMENT PRINCIPLE
ANALYSIS
Figure.1 shows the proposed tunable laser-based
bidirectional 10-Gb/s/λ channel-reuse DWDM PON
scheme. In the optical line terminal (OLT), 10-Gb/s
downstream data is modulated by on-off keying (OOK)
intensity modulation transmitter in every channel, and
we use DD receivers to receive the upstream signal
which is transmitted from the optical network unit
(ONU). A three-port optical circulator (OC) is used to
cross connect the downlink source and the uplink
receiver. In ONU side, an ONU consists of an OOK
intensity modulation transmitter, a 99:1 optical couple, a
power meter and a DD receiver. The uplink transmitter is
constituted by a tunable wavelength laser diode (TLD)
and a MZM modulator. In order to avoid the huge RB
that drop fiber generated, we used two drop fiber to
transmit upstream and downstream signal separately.
Uplink and downlink drop fiber is cross connected by a
three-port OC at the remote note (RN). In front of the
arrayed waveguide grating (AWG) at the remote node
(RN), a device constituted of a 95:5 optical couple and
2015 14th International Conference on Optical Communications and Networks (ICOCN) @ Nanjing, China
978-1-4673-7373-9/15/$31.00 ©2015 IEEE