INTERMODULATION DISTORTION FOR A HYBRID AM-VSB DIGITAL SYSTEM USING A1.55-MU-M LASER AND AN OPTICAL AMPLIFIER/

The performance of a hybrid AM-VSB/BPSK optical fiber transmission sys tem utilizing 1.55-mu m distributed feedback (DFB) laser and Er doped optical amplifier is presented. A BPSK modulated 2-MHz pseudorandom di gital channel is substituted for one of the AM channels in a 60-channe l CATV system and optically transmitted using a directly modulated 1.5 5-mu m DFB laser. The intermodulation distortion effects with and with out optical amplification were studied. No degradation of the AM chann els is observed unless the modulation depth of the BPSK channel is inc reased far beyond the level required for successful transmission to th e point where laser clipping effects become significant.