Title :
Coherent optical QPSK intradyne system: concept and digital receiver realization
Author_Institution :
Siemens AG, Munchen, Germany
fDate :
9/1/1992 12:00:00 AM
Abstract :
A receiver concept based on optical quadrature phase-shift keying (QPSK) and a digital realization of synchronous demodulation including phase synchronization is presented. To keep the signal processing bandwidth low a phase diversity receiver, called an intradyne receiver, with an orthogonal electrical demodulation is proposed. Basic principles of the synchronous orthogonal and digital demodulation are described. After the evaluation of the shot noise limit some aspects of the digital phase-locked loop (PLL) are presented. In a 100-Mb/s transmission system a receiver sensitivity of -51.6 dBm has been measured. The loss in relation to the shot noise limit of -66.3 dBm (18 photons/b) is mostly due to the low local laser power and the influence of the receiver input noise
Keywords :
demodulators; digital communication systems; optical modulation; optical receivers; phase shift keying; phase-locked loops; 100 Mbit/s; QPSK; coherent optical QPSK intradyne system; digital phase-locked loop; digital receiver; intradyne receiver; optical quadrature phase-shift keying; orthogonal electrical demodulation; phase diversity receiver; phase synchronization; receiver sensitivity; shot noise limit; signal processing bandwidth; synchronous demodulation; Bandwidth; Demodulation; Laser noise; Optical receivers; Optical sensors; Optical signal processing; Phase locked loops; Phase noise; Phase shift keying; Quadrature phase shift keying;
Journal_Title :
Lightwave Technology, Journal of
