Performance comparison of delay-interferometer based direct detection oDOPSK receivers.

Performance evaluation of five different delay-interferometer based direct detection optical differential octal phase-shift keying receivers is reported. The performance is evaluated under an amplified spontaneous emission noise limited scenario using the well known Karhunen Loeve series expansion method. The classification of receivers into five different types is based on either the receiver schematic or the algorithm/methodology employed for symbol estimation.