All-fiber divergence limiter

1. An optical fiber-based divergence-limiting device for limiting divergence from a first maximum divergence of input light to a second maximum divergence of output light, in which the second maximum divergence is less than the first maximum divergence, the optical fiber-based divergence-limiting device comprising:

an input optical fiber configured to receive the input light;

an output optical fiber configured to deliver the output light;

an intermediate optical fiber spliced between the input optical fiber and the output optical fiber, the intermediate optical fiber comprising:

a core configured to receive the input light, through which a first portion of the input light is configured to be guided from the input optical fiber to the output optical fiber, the core having a numerical aperture configured to limit the first portion of the input light to that having the second maximum divergence or less; and

a cladding covering at least a portion of the core and through which a second portion of the input light is configured to be removed from the core, the numerical aperture is further configured to limit the second portion of the input light to that having a greater divergence than the second maximum, and the first portion of the input light is coupled to the output optical fiber to form the output light.

2. The optical fiber-based divergence-limiting device of claim 1 , further comprising an enclosure housing a least a portion of the cladding from which stripped light is configured to be emitted and absorbed by an internal surface of the enclosure.

3. The optical fiber-based divergence-limiting device of claim 1 , in which a cladding-light stripper (CLS) fiber comprises the core and cladding.

4. The optical fiber-based divergence-limiting device of claim 3 , in which the CLS fiber includes a CLS region along a lengthwise portion of the CLS fiber.

5. The optical fiber-based divergence-limiting device of claim 4 , in which the CLS region is a coated section along the cladding, in which the coated section has a refractive index that is greater than or equal to that of the cladding.

6. The optical fiber-based divergence-limiting device of claim 4 , in which the CLS region includes a roughened-surface section along the cladding.

7. The optical fiber-based divergence-limiting device of claim 6 , in which the CLS region is chemically treated or laser processed.

8. The optical fiber-based divergence-limiting device of claim 4 , in which the CLS region includes a structured-surface section along the cladding.

9. The optical fiber-based divergence-limiting device of claim 4 , further comprising a fiber coil in the CLS region.

10. The optical fiber-based divergence-limiting device of claim 4 , further comprising a fiber taper in the CLS region.

11. The optical fiber-based divergence-limiting device of claim 1 , further comprising a fiber taper formed in the core and cladding.

12. The optical fiber-based divergence-limiting device of claim 1 , further comprising an input pigtail including the input optical fiber.

13. The optical fiber-based divergence-limiting device of claim 1 , further comprising an output pigtail including the output optical fiber.