55DB CNR OVER 50KM OF FIBER IN AN 80-CHANNEL EXTERNALLY-MODULATED AM-CATV SYSTEM WITHOUT OPTICAL AMPLIFICATION

The authors demonstrate supertrunking quality performance in an extern ally modulated 1550nm AM-CATV system over a 50km fibre link for the fi rst lime without the use of optical amplification. This performance ha s been enabled by a high power 1550nm DFB laser module (17dBm fibre-co upled output) and differential detection. High power (9.5dBm), low noi se signals from the complementary outputs of an LiNbO3 intensity modul ator were launched into two parallel fibres. After 50 km, RF subcarrie rs from two receivers recombined in phase increasing the carrier to no ise ratio by 3dB. The above configuration has allowed 80 NTSC channels to be transmitted with CNR > 55dB, CSO, CTB < -65dBc.