We demonstrate the use of a Lossless Integrated Active Splitter (LIAS), fabricated by Thallium ion-exchange in a planar Erbium/Ytterbium co-doped silicate glass substrate, pumped at 980 nm in an analog CATV distribution system at 1.5µm.
An optical access network is being constructed as part of the RACE programme to demonstrate the feasibility of providing both interactive broadband and television distribution services over a single, shared fibre to a residential subscriber. The interactive and distributive services will be transmitted in the 1.3 μm and 1.5 μm optical windows, respectively, of the fibre. To prevent crosstalk between the two services a wavelength division demultiplexer which gives adequate isolation between the two optical carriers must be provided at the subscriber receiver. Performance deterioration due to mutual crosstalk is calculated and measurement results presented. Theory and measurement show that the deterioration of the interactive signal caused by the distributive signal sets the most demanding isolation requirement. For an interactive signal penalty of 0.5 dB the isolation has to be 40 dB, which is at the limit of the performance achieved by commercially available wavelength division demultiplexers.
The stimulated Brillouin scattering threshold power in externally modulated lightwave AM-CATV systems can be increased up to 8 dB by single tone phase modulation of the optical carrier, without introducing significant intermodulation distortion even if the signal wavelength is not in the zero dispersion regime of the fibre.
Summary form only given. In this paper we show that with a directly modulated transmitter in a CATV transport and distribution system with cascaded Er-doped fiber amplifiers (EDFAs) similar power budgets and transmission distances can be achieved as in an externally modulated system, without electronic predistortion, by using dispersion compensating fiber (DCF) and carefully designed EDFAs with low gain-slope.
To introduce broadband interactive services in a fibre-coax CATV network with high splitting ratio, a HDWDM upgrading strategy in combination with conventional TDMA (or SCMA) techniques is presented. It features flexible network reconfiguration via wavelength reassignment at the optical network units. Key system item is a novel cost-effective bi-directional erbium-doped fibre (/planar waveguide) amplifier handling simultaneously a high-grade analogue CATV downstream signal and multiwavelength interactive signals in a single fibre-coax network.
Presents an externally modulated 50-channel AM-VSB video lightwave system, employing three cascaded EDFAs. For system specifications of SNR=46 dB, CSO<-66 dBc and CTB<-55 dBc, up to 40 000 ONUs can be connected to a single transmitter unit at distances larger than 30 km with standard nondispersion-shifted fiber. Interferometric noise and SBS are suppressed using single-tone phase modulation.< >
The authors have experimentally observed self-phase-modulation induced CSO distortion in externally modulated AM-VSB trunk lightwave systems using 50 km of standard fibre. The onset of this distortion occurs at power levels below those needed to generate stimulated Brillouin scattering.
Self-phase-modulation (SPM) in intensity-modulated systems causes frequency chirp, which in combination with fiber dispersion generates second-order distortion. It has been shown theoretically that in externally modulated systems, this effect can cause intolerable amounts of composite second-order (CSO) distortion, if the length of the feeder section between the CATV head-end and the local exchange exceeds a few tens of kilometers. We will for the first time present experimental data, supporting the theoretical analysis.
