S-band light sources using erbium-doped fiber with depressed cladding

摘要

A source that employs an Erbium-Doped Fiber Amplifier (EDFA) for generating light in an S-band of wavelengths. The EDFA uses a fiber having a core with a core cross section surrounded by a depressed cladding with a depressed cladding cross section and a secondary cladding with a secondary cladding cross section. A pump source is provided for pumping the Erbium contained in the core of the fiber to a high relative inversion D, such that the Erbium exhibits positive gains in the S-band and high gains in a long wavelength band longer than the S-band. The core cross-section, the depressed cladding cross-section, and the refractive indices n_o, n₁, and n₂ are selected to produce losses at least comparable to the high gains in the long wavelength band and losses substantially smaller than the positive gains in the S-band. The source uses the amplified spontaneous emission (ASE) produced by the EDFA to generate broadband light and/or narrowband light with the aid of a wavelength selecting mechanism that selects an output wavelength of the light within the ASE emission spectrum of the EDFA.