F.W. Willems

Simultaneous suppression of stimulated Brillouin scattering and interferometric noise in externally modulated lightwave AM-SCM systems

Externally modulated AM-SCM lightwave systems employing optical power amplifiers, small linewidth DFB lasers and long optical feeder lines, face low stimulated Brillouin scattering threshold powers and phase-to-intensity noise conversion by multipath interference through Rayleigh scattering. We show that these problems can be effectively counteracted simultaneously without introducing additional intermodulation distortion, both by single tone phase modulation and by dithering of the lasers optical frequency.<<ETX>>

A 50-channel externally modulated AM-VSB video distribution system with three cascaded EDFA's providing 50-dB power budget over 30 km of standard single-mode fiber

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.<<ETX>>

Mutual deterioration of WDM-coupled AM-CATV and digital B-ISDN services in single fiber access networks

In single-fiber access networks with interactive and distributive services multiplexed at different wavelengths, the interactive signal may disturb the distributive signal, and vice versa, because of imperfect isolation of the demultiplexing WDM at the subscriber site. The mutual deterioration of a 622-Mb/s intensity-modulated (IM) broadband ISDN (B-ISDN) signal at 1.3 mu m and an AM subcarrier-multiplexed (SCM) TV-distribution signal at 1.55 mu m is investigated. Both theory and experiment show that the isolation of the demultiplexing WDM must keep the undesirable 1.3- mu m, 622-Mb/s IM signal power on the analog receiver below -36 dBm to avoid degradation of the analog system CNR of 47 dB by more than 1 dB.<<ETX>>

Experimental demonstration of noise figure reduction caused by nonlinear photon statistics of saturated EDFA's

For the first time, experimental evidence is presented for the prediction that the noise figure for an EDFA in the nonlinear or saturated regime, calculated by measuring the ASE power, can lead to an overestimation when compared to a direct measurement of the noise variance with an electrical spectrum analyzer. These results are in line with theories based on the quantum mechanical photon master equation describing an optical amplifier with saturated upper and lower ion inversion levels.<<ETX>>

Experimental verification of self-phase-modulation-induced nonlinear distortion in externally modulated AM-VSB lightwave systems

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.

Evolution-friendly upgrade of CATV networks towards a broadband full services access network

Summary form only given. To summarize, the described WDM-APON (WDM ATM-PON) technique which multiplexes four standard 622/155 Mbit/s APON systems over an amplified 1:64 split ODN, with approximately 40 customer premises connected to one ONU, enables a maximum available capacity per IUP of400 kbit/s downstream and 100 kbit/s upstream and peak rates of 32 Mbit/s downstream and 8 Mbit/s upstream. The total number of customers that can be connected to this system is approximately 2400. The AM-CATV service can be delivered to all customers connected.

Directly modulated AM-VSB lightwave video transmission system using dispersion-compensating fiber and three cascaded EDFAs, providing 50-dB power budget over 38 km of standard single-mode fiber

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.

A low-cost intrinsically low-distortion EDFA design for AM-CATV applications with a wide input power and wavelength range

We present a 980 nm pumped low-cost EDFA design for AM-CATV applications with intrinsic low distortion and noise-figure over a wide input power and wavelength range by using an optimized Erbium Doped Fibre.

Carrier-to-Noise Ratio Degradation due to Signal Double Rayleigh Scattering in EDFAs used in AM-SCM CATV Systems for the Local Loop

Amplified signal double Rayleigh scattering in Erbium doped fibres causes excess intensity noise that can degrade CNR in AM-CATV systems employing EDFAs.

First prototype of bi-directional EDFA for single fiber tree-and-branch access networks carrying AM-VSB and digital multiwavelength signals

Summary form only given. Optical fiber is penetrating rapidly in subscriber access networks for distribution of community antenna television (CATV) services. Todays CATV head-end stations are feeding distributive services to large numbers of subscribers (>10,000) in networks with abundant splitting in the fiber part as well as in the coaxial part. The ACTS project TOBASCO (Towards Broadband Access Systems for CATV Optical networks) is exploring ways to upgrade existing fiber-coax CATV networks to implement such interactive services by developing HDWDM techniques and optical bi-directional amplifiers. We present the design and performances of a bi-directional multiwavelength TWOBA (two wavelength optical branching amplifier) used to compensate the propagation and the splitting losses along the link for bi-directional digital interactive signals and downstream analogue CATV signal.