Accession Number : ADP006990

Title :   System Limitations for Fiber Amplifier Cascades,

Corporate Author : NIPPON TELEGRAPH AND TELEPHONE CORP TAKE TRANSMISSION SYSTEMS LABS

Personal Author(s) : Ito, Takeshi

Report Date : 22 MAY 1992

Pagination or Media Count : 4

Abstract : The performance, of an amplifier cascade system is taken to be the product of transmission bit rate, B, and transmission distance, L. In amplifier cascade systems using the IM/DD scheme, signal spontaneous beat noise, spontaneous-spontaneous beat noise and shot noise are present in addition to receiver thermal noise, while local oscillator shot noise and local oscillator-spontaneous beat noise are additional factors in coherent systems. Signal-spontaneous and spontaneous-spontaneous beat noises generally predominate in IM/DD systems if many cascaded amplifiers are used. Conversely, in coherent systems, local oscillator-spontaneous beat noise predominates. In such cases, system performance is approximated by B X L = fmod(SNR, /) X (PS/NF), where fmod(SNR, /) is a function of required SNR and amplifier spacing, /, depending on the mod/demod scheme, Ps is the amplifier output power, and NF is the amplifier noise figure. Therefore, the system performance depends on amplifier spacing and amplifier performance given as PS/NF. As the spacing decreases and/or amplifier performance increases, system performance increases. However, it is limited by four conditions: (1) Fiber dispersion, (2) Amplifier performance, (3) Noise accumulation, and (4) No cascaded amplifier.

Descriptors :   *AMPLIFIERS, ACCUMULATION, ADDITION, FUNCTIONS, LOCAL OSCILLATORS, NOISE, OSCILLATORS, OUTPUT, POWER, RATES, RECEIVERS, SHOT NOISE, SIGNALS.

Subject Categories : Electrical and Electronic Equipment
      Fiber Optics and Integrated Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE