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Worldwide first realtime synchronous optical quadrature phase shift keying data transmission with standard lasers
PADERBORN, Germany - On 30th June 2006, the Univ. Paderborn in Germany and
CeLight Israel announce the worldwide first realtime synchronous optical quadrature
phase shift keying data transmission with standard lasers. This breakthrough
was achieved in the consortium "Key Components for Synchronous Optical
Quadrature Phase Shift Keying Transmission" funded by the European Commission.
The innovative "synQPSK" modulation scheme can quadruple optical
fiber capacity when combined with additional polarization division multiplex,
and allows for a purely electronic equalization of fiber chromatic and polarization
mode dispersions.
Using an integrated-optical 90° hybrid and a local laser, a coherent optical
receiver was constructed, where the received optical QPSK signal is down-converted
to the electrical domain in phase and in quadrature. After analog-to-digital
conversion a digital signal processor recovers the carrier in realtime and
demodulates data. It closely tracks even large amounts of phase noise introduced
by the utilized standard distributed-feedback lasers with a sum linewidth
of 4 MHz. At a line rate of 400 Mbaud, corresponding to 800 Mb/s, the achieved
bit error ratio is within the threshold of a state-of-the-art forward error
correction scheme (FEC). These findings have just been reported at the Coherent
Optical Technologies and Applications meeting of the Optical Society of America.
Most recently, the researchers in Paderborn have doubled the data rate, thereby
significantly improving the bit error ratio. Further benefits are expected
from the planned incorporation of QPSK modulators from Photline, France, balanced
photoreceivers from the Univ. Duisburg-Essen, Germany, miniaturized 90°
hybrid front ends and advanced microelectronic circuits. But even today's
results allow to predict unproblematic operation with an in-band or even with
no FEC at 10 Gbaud (4 x 10 Gb/s per wavelength with polarization multiplex).
The partners believe that their synQPSK technology will allow for an evolutionary,
graceful growth of optical transmission capacity in an economically sensitive
environment.
T. Pfau, S. Hoffmann, R. Peveling, S. Bhandare, S. Ibrahim, O. Adamczyk, M. Porrmann, R. Noé, Y. Achiam:
Real-time Synchronous QPSK Transmission with Standard DFB Lasers and Digital I&Q Receiver
, Proc. OAA/COTA2006, CThC5, June 25-30, 2006, Whistler, Canada.
http://www.osa.org/meetings/topicals/oaa/