Patent ID: 6941053

Claim:
A triple-clad optical fiber for high power cladding-pumped fiber amplifiers and lasers, the triple-clad fiber comprising the following elements: a singlemode core doped to provide an amplification region, and an inner cladding disposed around said core, and an intermediate cladding disposed around said inner cladding and larger than said inner cladding for guiding pump power, and an outer cladding disposed around said intermediate cladding, and wherein: said inner cladding has a refractive index lower than a refractive index of said core and higher than a refractive index of said intermediate cladding allowing for a low numerical aperture of said core, and said outer cladding has a refractive index lower than the refractive index of said intermediate cladding allowing said pump power to be convinced inside a volume limited by said outer cladding.