Coherent Optical TV Distribution Network

Abstract

We report the performance (over a time period of five days) of a rack mounted 8 channel coherent TV distribution system (Photo 1). The 8 transmitter lasers are commercially available quarterwave shifted 1551 nm DFB lasers, modulated with a 140 Mbit/s CMI line coded signal. The linewidth varies between 18 and 40 MHz. The linewidth as a function of the inverse output power is given in Fig. 3. The laser output power amounts to 10 mW, the coupling loss is 7.5 dB. The structure of the module is given in Fig. 2. The emitted radiation of all lasers is FSK modulated with a shift of 2.7 GHz and combined by an 16*2 combining network. One output of this device is transmitted over an installed 11 km long cable running through the city of Berlin. It is further expanded by an 1*64 distribution network. This system has the capability to support 1024 subscribers with a power margin of 4 dB. The structure of the system is given in Figure 1 and the power budget is shown in Figure 8.