Differential
Quaternary Phase-Shift Keying (DQPSK) is the four-level
version of DPSK. DQPSK
transmits two bits for every symbol (bit combinations
being 00, 01, 11 and 10) and has an additional advantage
over conventional binary DPSK. DQPSK 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 to achieve
the expanded flexibility of reducing system cost by using
low-speed drive electronics.
Optoplex's
Optical DQPSK demodulator converts quadratural
phase modulation into amplitude modulation
over the entire C+L band in support of data transmission
rate of 10 or 40 Gb/s. DQPSK demodulator is designed
for the next generation optical communications systems
utilized in commercial, defense and space exploration
markets. The device plays a key role in improving signal
quality and performance to meet the expanding demand for
higher data rates and more complex transmission formats
within current and next generation systems without major
capital expenditure.
- DQPSK
demodulator uses half the transmission rate to achieve
the same data rate (20-Gb/s system for 40-Gb/s data
rate, with four phase states instead of two in DPSK
format)
- Lower
transmission rate saves cost on many other components
and electronics and is more tolerate of dispersion
- 20-Gb/s
system is the highest transmission rate possible for
the 50-GHz channel spacing
-
Optoplex’s DQPSK demodulator currently provides
a convenient solution for this application by using
two matched DPSK demodulators
with phase off-set at ± π/4. The co-packaged
single-core DQPSK demodulator is also under development
For DPSK demodulator or Delay
Line Interferometer, please visit DPSK
Demodulator page.
