Fremont,
CA, February 23, 2006 – Optoplex Corporation
recently shipped a highly customized differential
quaternary phase-shift keying (DQPSK) demodulator
to be utilized in a field trial for a next-generation
40 Gb/s fiber-optic transmission systems to be deployed
by a major European service provider in 2007 and beyond.
Differential
phase-shift keying (or DPSK) is touted as the most
promising modulation format for optical communication
systems, offering a 3-dB improvement in receiver sensitivity
compared with standard on-off keying. The four-level version
of DPSK, DQPSK, transmits two bits for every symbol, has
an additional advantage over conventional binary DPSK
in that it has a narrower optical spectrum, which tolerates
more dispersion (both chromatic and polarization-mode),
allows for stronger optical filtering, and enables closer
channel spacing. As a result, DQPSK is the only modulation
format which allows processing of 40Gb/s data-rate in
a 50-GHz channel spacing system.
With
DQPSK, the bandwidth of the drive electronics needs only
be half of the bit rate, so 43 Gb/s signals can be generated
with 21.5 Gb/s equipment. This allows system providers
the expanded flexibility of reducing system cost by using
low-speed drive electronics.
Optoplex’s
DPSK and DQPSK
demodulators are designed specifically for the next generation
optical communication systems utilized by commercial,
defense and space exploration markets.
