Patent ID: 6278816
Filing Date: 2001-08-21
Classification: C03B,G02B,H01S

Abstract:
A method of fabricating a low-noise cladding pumped optical amplifier from a double-clad optical fiber that includes a transparent outer region, a transparent intermediate region with a higher refractive index than the outer region and an inner region with higher refractive index than the intermediate region, where a pump wavelength is absorbed and converted into optical gain at a signal wavelength, the outer and intermediate regions forming a multimode waveguide and the intermediate and inner region forming a waveguide that is embedded in the multimode waveguide and which is singlemode at the signal wavelength, the fiber having an input and an output end, the method comprising:introducing a selective loss into the fiber, such that only a mode at the signal wavelength that propagates with low loss between the input and output ends of the fiber is a fundamental mode of the singlemode waveguide defined by the inner region of the fiber, and such that a length of the fiber that will not be excited by multimode pump radiation propagating from either the input or output end of the fiber is negligible.