Alternate-mark-inversion optical continuous phase FSK heterodyne transmission using delay-line demodulation

Alternate-mark-inversion (AMI) optical continuous phase (CP) frequency-shift keying (FSK) heterodyne transmission using delay-line demodulation which has a higher receiver sensitivity compared to the transmission using single-filter demodulation has been achieved. Since the proposed delay-line demodulation method directly converts the received AMI-CPFSK signal into the nonreturn to zero (NRZ) baseband signal without the use of an AMI decoder, a heterodyne receiver with the same configuration as the conventional CPFSK transmission system is realized, even though AMI line coding is applied to the system. Transmission experiments at 622 Mb/s have been demonstrated for both pseudorandom 2⁷-1 and 2²³-1-b patterns at the same receiver sensitivity of -41.1 dBm (the PD input power)