self-coherent optical modulation formats such as binary DPSK (DBPSK), DQPSK,
and DPSK in combination with amplitude shift keying (A SK) and polarization
multiplexing. Section 4.3 describes the principle of differential direct-detection,
particularly orthogonal differential direct detection for multilevel DPSK. Section
4.4 presents the principle and implementation of digital self-coherent receiver that
couples orthogonal differential direct-detection with ADC and DSP. Digital field
reconstruction and data-aided multisymbol phase estimation (MSPE) will be dis-
cussed. Section 4.5 introduces adaptive equalization techniques that can be com-
monly used in digital self-coherent receiver as well as digital coherent receiver to
compensate or mitigate tran ...