For example, although 10 Gbit/s systems typically utilize NRZ intensity modulation, it is necessary to employ more advanced modulation formats, such as duobinary
(DB) or phase shift keying (PSK) modulation to move to the rate of 40 Gbit/s and higher .
Fukuchi et al., "Characteristics of optical duobinary
signals in terabit/s capacity, high-spectral efficiency WDM systems," Journal of Lightwave Technology, vol.
Mochizuki, "614 Mbit/s OOK-based transmission by the duobinary
technique using a single commercially available visible LED for high-speed visible light communications," in Proceedings of the European Conference and Exhibition on Optical Communication (ECEOC '12), P4.03, Optical Society of America, Amsterdam, The Netherlands, September 2012.
To mitigate the effect of ICI and to overcome the transmitter complexity of MC-CDMA system, duobinary
coded receiver phase rotated conjugate cancellation (RPRCC) with pilot based CFO estimation is proposed in this work.
In the following equations we consider a postcursor channel with L = 1 and [d.sub.1] = 1 (i.e., a duobinary
modulation, which changes the phase of the optical signal of each "1" bit for a certain sequence of bit and reduces the average optical signal power by one-half.
The portfolio features products with different modulation formats, including NRZ, negative-chirp NRZ, Duobinary
and high dispersion tolerance, the company claims.
Inphi's 13750DE/13751DE Differential Encoder is said to be the first commercially available single-chip encoder to provide up to 12.5 Gbps Differential Phase Shift Keying (DPSK) or Duobinary
Bell Labs employed Duobinary
Signalling which uses three electrical (positive, negative and zero) signal levels and requires less bandwidth than NRZ signals and enabled the optical 107Gb/s serial data stream to be created.
TU5A-3: 10 Gb/s Electrical Backplane Transmission Using Duobinary
A cost-effective solution was based on duobinary
modulation  and the adjustments of the RSOA's electro-optical (E/O) response to a 2.5 GHz Bessel filter.
Yano et al., "Feasibility study on over 1 bit/s/Hz high spectral efficiency WDM with optical duobinary
coding and polarization interleave multiplexing," in Proceedings of the Optical Fiber Communication Conference (OFC '97), pp.