Nonlinear fiber amplifiers used for a 1430-1530nm low-loss window in optical fibers

US6101024A · kind A · utility

Assignee

• Xtera Communications, Inc. · US

Inventors

• Mohammed N. Islam · Romford, GB
• Hayden Henry Harris · Chelsea, US

Key dates

• Filing date: Mar 24, 1998
• Grant date: Aug 8, 2000
• Expiry date: Mar 24, 2018

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04B2210/258
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An apparatus and method are described for exploiting almost the full almost 25 THz of bandwidth available in the low-loss window in optical fibers (from 1430 nm to 1620 nm) using a parallel combination of optical amplifiers. The low-loss window at about 1530 nm-1620 nm can be amplified using erbium-doped fiber amplifiers (EDFAs). However, due to the inherent absorption of the erbium at shorter wavelengths, EDFAs cannot be used below about 1525 nm without a significant degradation in performance. For the low-loss window at approximately 1430-1530 nm, amplifiers based on nonlinear polarization in optical fibers can be used effectively. A broadband nonlinear polarization amplifier (NLPA) is disclosed which combines cascaded Raman amplification with parametric amplification or four-wave mixing. In particular, one of the intermediate cascade Raman order wavelengths .lambda..sub.r should lie in close proximity to the zero-dispersion wavelength .lambda..sub.0 of the amplifying fiber. For this intermediate Raman order, spectral broadening will occur due to phase-match with four-wave mixing (if .lambda..sub.r <.lambda..sub.0) or phase-matched parametric amplification (if .lambda..sub.r >.la…