Fiber optic coupler, optical fiber useful with the coupler and/or a pump light source, and methods of coupling light

Optical apparatus, comprising:

• an optical fiber coupler including at least a first input optical fiber and at least one output optical fiber, said first input optical fiber comprising an antiguiding core, a first cladding disposed about said antiguiding core and a second cladding disposed about said first cladding so as to tend to confine light to said first cladding, said output optical fiber comprising a guiding core, a first cladding disposed about said guiding core and a second cladding disposed about said first cladding of said output optical fiber for tending to confine light to said first cladding of said output optical fiber, and
• wherein said optical fiber coupler comprises a tapered fiber bundle.

Optical apparatus, comprising:

• an optical fiber coupler including at least a first input optical fiber and at least one output optical fiber, said first input optical fiber comprising an antiguiding core, a first cladding disposed about said antiguiding core and a second cladding disposed about said first cladding so as to tend to confine light to said first cladding, said output optical fiber comprising a guiding core, a first cladding disposed about said guiding core and a second cladding disposed about said first cladding of said output optical fiber for tending to confine light to said first cladding of said output optical fiber, and
• wherein said first input optical fiber comprises a longitudinally extending aperture defined by said first cladding, said antiguiding region comprising said aperture.