Optical: systems and elements – Optical amplifier – Raman or brillouin process
Reexamination Certificate
2001-07-26
2003-02-25
Hellner, Mark (Department: 3662)
Optical: systems and elements
Optical amplifier
Raman or brillouin process
C359S341300
Reexamination Certificate
active
06525870
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates generally to a method and system for controlling Raman gain flatness sensitivity to pump laser wavelength variations in an optical communications system utilizing Raman amplification.
2. Description of Related Art
Raman amplifiers are used in optical communications networks in applications such as ultra long haul transmissions. Energy from pump lasers is transferred to the signal carrying wavelengths through stimulated Raman scattering (SRS) to thereby amplify the signal.
In wavelength division multiplexed (WDM) systems, it is known to be desirable to provide uniform gain across multiple channels, a concept referred to as gain flatness. Unfortunately, conventional Raman amplifiers may generate non-uniform gain due to a number of factors. First, the pump lasers will have variance in the output wavelength due to manufacturing tolerances. Typically, pump laser manufacturers can deliver pump lasers with ±1.0 nm tolerance at room temperature (25° C.). In addition to pump laser wavelength tolerances, the temperature dependence of Raman amplifier components can shift the pump laser wavelength significantly over −5° C. to 55° C. ambient temperature. Existing Raman amplifiers may experience a temperature dependence of ~0.02 nm/° C., which corresponds to a ~1.2 nm shift over −5° C. to 55° C. ambient temperature. Thus, the worst case of pump laser wavelength deviation can be ±1.6 nm with the combination of wavelength tolerances from pump manufacturers and temperature dependent effects on laser wavelength.
FIG. 1
illustrates the deleterious effect of wavelength variance on gain flatness. As shown in
FIG. 1
, the Raman gain varies widely with variance in pump laser wavelength. These wavelength variances degrade the distributed Raman amplifier performance due to the increased gain ripple (i.e., reduced gain flatness) and eventually limit the transport distance of signals on the transmission path.
REFERENCES:
patent: 4699452 (1987-10-01), Mollenauer et al.
patent: 5159601 (1992-10-01), Huber
patent: 5673129 (1997-09-01), Mizrahi
patent: 5875273 (1999-02-01), Mizrahi et al.
patent: 5943152 (1999-08-01), Mizrahi et al.
patent: 6091744 (2000-07-01), Sorin et al.
patent: 6115174 (2000-09-01), Grubb et al.
patent: 6118914 (2000-09-01), Davis et al.
patent: 6163552 (2000-12-01), Engelberth et al.
patent: 6389200 (2002-05-01), Foltzer
patent: 0867736 (1998-09-01), None
patent: WO 97/31289 (1997-08-01), None
Raman Amplification in Wideband WMD Transmission, Web ProForum Tutorial, International Engineering Consortium, date unknown.
Jiang et al, “A Novel Strain-Induced Thermally Tuned Long-Period Fiber Grating Fabricated on a Periodic Corrugated Silicon Fixture” (2002), IEEE Photonics Technology Letters, vol. 14, No. 7, pp 941-943.
Bao Jun
Cho Si Hyung
Sridhar Balakrishnan
Tsou Jon
Cammarata Michael R.
Ciena Corporation
Fox David A.
Hellner Mark
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