42 GBd 3-bit power-DAC
17 March 2011
High capacity optical transmission systems with optimized spectral efficiency are presently intensively investigated [1]. Modulation formats offering spectral efficiency superior to on/off keying and in particular multilevel coded transmission such as M-ary Quadrature Amplitude Modulation (M-QAM) and operating at high symbol-rate are of particular interest. Different solutions are presently investigated to realize QAM transmitters. The optical multimodulator transmitters combine binary signals in the optical domain. An alternative option is to apply multi-level electrical signals to the much simpler I/Q modulator. The most popular architecture for generation of multilevel electrical signal is composed of high-speed electrical digital-to-analogue converter (DAC)
