Patent ID: 8611002
Filing Date: 2013-12-17
Classification: H01S

Abstract:
1. An optical fiber device for providing optical gain at a selected wavelength, the optical fiber device comprising: one or more sources of optical pump energy; a first length of optical fiber comprising a core and a first cladding disposed about the core, the first cladding and core configured to guide light of a selected wavelength, the core comprising a concentration of a rare earth for providing the optical gain in response to receiving optical pump energy, the core comprising a first cross-sectional region within which the concentration of the rare earth does not fall below 50% of its highest concentration, the first length of optical fiber further comprising a second cladding disposed about the first cladding, the second cladding having a lower refractive index than the first cladding, the second cladding being configured to confine the optical pump energy from the optical pump source to the first cladding and the core of the first length of optical fiber; and a second length of optical fiber comprising a core and a first cladding disposed about the core, the first cladding and core configured to guide light of the selected wavelength, the core comprising a concentration of the rare earth for providing the optical gain in response to receiving optical pump energy, the core comprising a first cross-sectional region within which the concentration of the rare earth does not fall below 50% of its highest concentration, the second length of optical fiber further comprising a second cladding disposed about the first cladding, the second cladding having a lower refractive index than the first cladding, the second cladding being configured to confine the optical pump energy from the optical pump source to the first cladding and the core of the second length of optical fiber, wherein the one or more sources of optical pump energy are optically coupled to the first length of optical fiber and the second length of optical fiber, such that the intensity of optical pump energy is higher in the first length of optical fiber than in the second length of optical fiber, and such that at least 2% of the fiber-coupled optical pump energy from each of the one or more sources of optical pump energy is delivered to the first length of optical fiber and the second length of optical fiber; and the first cross-sectional region of the core of the second length of optical fiber is larger in area than the first cross-sectional region of the core of the first length of optical fiber; and the overlap integral η is smaller in the first length of optical fiber than in the second length of optical fiber, the overlap integral being calculated by the equation