Title :
Optimum system design for CPFSK heterodyne delay demodulation system with DFB LDs
Author :
Emura, Katsumi ; Sato, Kaoru ; Yamazaki, Shuntaro ; Murata, Shigeru ; Shikada, Minoru ; Minemura, Kouichi
Author_Institution :
NEC Corp., Kawasaki, Japan
fDate :
2/1/1990 12:00:00 AM
Abstract :
An optimum system configuration for an optical continuous-phase frequency-shift-keying (CPFSK) heterodyne delay demodulation system with distributed feedback laser diodes (DFB LDs) is discussed. The optimum modulation index was determined by evaluating the LD phase noise effect and the IF noise effect. The IF noise effect was investigated in detail, considering the noise conversion effect through delay demodulation. In the case of 10-MHz IF beat spectral width, the modulation index m =1.5 is optimum for a 1.2-Gb/s system. With this optimum modulation index, a 204-km long-span transmission experiment, with -41.5 dBm receiver sensitivity, has been successfully performed. The feasibility of using stand-alone DFB LDs for a high-sensitivity CPFSK delay demodulation system has been confirmed through this experiment
Keywords :
delay lines; demodulation; distributed feedback lasers; frequency shift keying; laser beam applications; optical communication equipment; semiconductor junction lasers; 1.2 Gbit/s; 204 km; IF noise effect; continuous-phase frequency-shift-keying; distributed feedback laser diodes; heterodyne delay demodulation system; modulation index; phase noise; Delay systems; Demodulation; Frequency; Optical feedback; Optical mixing; Optical modulation; Optical noise; Optical receivers; Optical sensors; Phase noise;
Journal_Title :
Lightwave Technology, Journal of
