Patent ID: 7283714

Claim:
A single mode holding, large mode area optical fiber for guiding light at an operating wavelength λ comprising: a core having an effective mode field diameter d 1 and an effective refractive index n 1 ; a first cladding having an effective mode field diameter d 2 and an effective refractive index n 2 , wherein n 2 <n 1 , and d 2 /d 1 <2, said core having an effective core numerical aperture NA 1 between about 0.02 and about 0.06; a second cladding having an effective index of refraction n 3 , wherein n 3 <<n 2 , and said first cladding having an effective numerical aperture NA 2 of greater than about 0.4; and a third cladding having an index of refraction n 4 , wherein n 4 >n 3 .