![](bg1.png)
The Effect of Filtering on the OSNR
For a 40- and 100 Gb/s DWDM System
Morad Khosravi Eghbal
Photonics Laboratory, Department of Microtechnology and Nanoscience MC2,
Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
Keywords: 100 Gb/s DP-QPSK, 40 Gb/s DPSK, OSNR, BER.
Abstract: Quality measures like Bit Error Rate (BER) and Optical Signal to Noise Ratio (OSNR) are important
indicators for verifying the quality of a received signal in the optical fiber communication. Different
components like Wavelength Selective Switches and Optical Interleaver Units used in a Dense Wavelength
Division Multiplexed network can decrease the operating bandwidth. This work investigates the effect of
bandwidth narrowing on the OSNR value in an optical fiber link.
1 INTRODUCTION
One of the advantages of high bit rates like 40- and
100 Gb/s in fiber optical communication is
increasing the bandwidth efficiency. This leads to an
increased capacity that is a key factor for a number
of bandwidth-demanding services. However, service
providers have widely invested in 10 Gb/s.
Therefore, it would be too costly to build new
infrastructures for higher bitrates while they
technically keep losing what they have spent in the
legacy bit rate. As a result, it is much more
affordable to use existing structure to transmit higher
bit rates systems. Birk et al. (2010:2-3) discussed
about coexistence of 10 Gb/s OOK and 40 Gb/s
DPSK with 100 Gb/s DP-QPSK in a 900 Km fiber
link. The filtering effect of Wavelength Selective
Switch (WSS) in the ROADMs at 10, 40 and 100
Gb/s have been presented in the literature.
(Heismann, F., Collings, B. and Reimer, C., 2009:2-
3; Zhang et al., 2010:2-3; Nelson et al. 2011;
Pinceman et al., 2011:2; Birk et al., 2011:1-2;
Heismann 2010). Also Mikkelsen et al. (2006:1)
have demonstrated the filtering effect of interleaver
units on a 40 Gb/s DPSK system.
The purpose of the work described in this paper
is to evaluate the destructing effect of narrowing the
bandwidth on OSNR value for a BER of 1.0E-12 for
40 Gb/s and 100 Gb/s .Signal bandwidth becomes
narrower when it passes through components that
have bandwidth smaller than that of 40 Gb/s and 100
Gb/s signals. For this work, these components are
Multiplexer/Demultiplexer units, Wavelength
Selective Switch, Optical Interleaver Unit and
finally Wavelength-Blocker. The 40 Gb/s (33%
Return-to-Zero) DPSK pseudorandom bit sequence
(PRBS) data stream in the C-band and 100 Gb/s DP-
QPSK optical signal transmitted in a network that
has been designed for 10 Gb/s OOK optical signals.
Because of the nature of higher bitrate signals, their
bandwidth is wider (compared to 10 Gb/s
signal).Various components like ROADMs,
interleaver units and filters have a tightening effect
on the effective bandwidth according to their active
bandwidth. This imposes a penalty on the quality of
the received signal. Such penalties are investigated
and the components which impose the tightest
filtration on the bandwidth are presented.
2 EXPERIMENTAL SETUP
The link shown in figure 1 is established for the
OSNR measurements. The input signals are
generated by a) 40 Gb/s NRZ-DPSK 300-pin MSA
transceiver with 191.70 to 196.10 THz C-band
frequency range on 50 GHz ITU grid and 38 GHz
spectrum width (3-dB Band width) and b) 100 Gb/s
PM-QPSK CFP 100 GbE with 191.70 to 196.10
THz C-band frequency range on 50 GHz ITU grid.
The frequency of the signal has been chosen as
193975 THz as it is in the middle of C-Band to
97
Khosravi Eghbal M..
The Effect of Filtering on the OSNR - For a 40- and 100 Gb/s DWDM System.
DOI: 10.5220/0004714000970101
In Proceedings of 2nd International Conference on Photonics, Optics and Laser Technology (PHOTOPTICS-2014), pages 97-101
ISBN: 978-989-758-008-6
Copyright
c
2014 SCITEPRESS (Science and Technology Publications, Lda.)