Split-band amplifying apparatus using a depressed-profile fiber amplifier
AssigneeLightwave Electronics Mountain View
InventorsMark A. Arbore, Jeffrey D. Kmetec, Yidong Zhou
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Abstract
A split-band amplifying apparatus that has a first section for amplifying a long wavelength band of an optical signal and a second section equipped with a fiber amplifier for amplifying a short wavelength band of the optical signal. The fiber amplifier in the second section uses a short-pass fiber with a depressed cladding cross-section and core doped with an active material, e.g., Erbium, and pumped to a high relative inversion D. The split-band amplifying apparatus can be used to amplify signals whose short wavelength band includes at least a portion of the S-band and whose long wavelength band includes at least a portion of the C- and/or L-band.
Claims21
A split-band amplifying apparatus comprising:
- a) a first section for amplifying a long wavelength band of an optical signal;
- b) a second section having a fiber amplifier for amplifying a short wavelength band of said optical signal, said fiber amplifier comprising:
- 1) a core having a core cross-section and a refractive index no;
- 2) an active material doped in said core;
- 3) a depressed cladding surrounding said core, said depressed cladding having a depressed cladding cross-section and a refractive index n1;
- 4) a secondary cladding surrounding said depressed cladding, said secondary cladding having a secondary cladding cross-section and a refractive index n2;
- 5) a pump source for pumping said active material to a high relative inversion D, such that said active material exhibits positive gains in said short wavelength band and high gains in said long wavelength band;
- wherein said core cross-section, said depressed cladding cross-section, and said refractive indices no, n1, and n2 are selected to produce a roll-off loss curve about a cutoff wavelength λc, said roll-off loss curve yielding losses at least comparable to said high gains in said long wavelength band and losses substantially smaller than said positive gains in said short wavelength band.
A method for split-band amplification using a split-band amplifying apparatus, said method comprising:
- a) providing a first section for amplifying a long wavelength band of an optical signal;
- b) providing a second section having a fiber amplifier for amplifying a short wavelength band of said optical signal, said fiber amplifier being constructed by:
- 1) providing a core having a core cross-section and a refractive index no;
- 2) doping said active material into said core;
- 3) providing a depressed cladding around said core, said depressed cladding having a depressed cladding cross-section and a refractive index n1;
- 4) providing a secondary cladding around said depressed cladding, said secondary cladding having a secondary cladding cross-section and a refractive index n2;
- 5) selecting said core cross section, said depressed cladding cross-section, and said refractive indices no, n1, and n2 to produce a roll-off loss curve about a cutoff wavelength λc, said roll-off loss curve yielding losses at least comparable to said high gains in said long wavelength band and losses substantially smaller than said positive gains in said short wavelength band.
Dependencies are inferred from the claim text.