Methods and apparatus related to a distal end of a side-fire optical fiber having multiple capillary components

1. An apparatus, comprising:

a first capillary extending along a longitudinal axis and having an open distal end, wherein a flat distal end face of the open distal end of the first capillary is perpendicular to the longitudinal axis; a second capillary disposed outside of the first capillary and having an inner surface and a flat open distal end face, wherein a portion of the inner surface of the second capillary is heat-fused to an outer surface of the first capillary;

an outer cover cap coupled to and disposed outside of the second capillary, and forming a distal end of the apparatus and an internal flat surface; and

an optical fiber, a portion of the optical fiber disposed inside of the first capillary and having an outer surface, wherein a portion of the outer surface of the optical fiber is heat-fused to an inner surface of the first capillary, the optical fiber having an angled distal surface configured to reflect electromagnetic radiation propagated along a longitudinal axis of a distal end portion of the optical fiber in a lateral direction through the inner surface of the first capillary and the inner surface of the second capillary, and the outer cover cap is configured to reflect stray laser energy internal to the apparatus, wherein the distal end face of the first capillary and the distal end face of the second capillary extend distally beyond the distal end surface of the optical fiber and the internal flat surface of the outer cover cap abuts the distal end face of the first capillary and the distal end face of the second capillary.

2. The apparatus of claim 1 , wherein the optical fiber has a dopant different than a dopant of the first capillary component, and wherein the portion of the optical fiber includes at least one cladding layer.

3. The apparatus of claim 1 , wherein the distal surface of the optical fiber and the outer cover define at least a portion of an enclosure.

4. The apparatus of claim 1 , wherein the electromagnetic radiation is emitted from a Ho:YAG laser source, Nd:YAG laser source, a semiconductor laser diode, or a laser source having a non-linear crystal element.

5. The apparatus of claim 1 , wherein the fiber is a low hydroxyl fiber.

6. The apparatus of claim 1 , wherein the first capillary and the second capillary are made of silica-based material and the outer cover cap is metallic or made of polymer-based material.

7. An apparatus, comprising: a side-fire laser fiber including a first capillary extending along a longitudinal axis and having an open distal end and an optical fiber, the open distal end of the first capillary having a flat distal end face perpendicular to the longitudinal axis, the first capillary being heat-fused to an outer surface of the optical fiber, the optical fiber having an angled distal end surface being within a plane non-normal to a longitudinal centerline of the optical fiber and configured to reflect laser radiation propagated along a longitudinal axis of a distal end portion of the optical fiber in a lateral direction through the first capillary and the second capillary;

a second capillary being heat-fused to an outer surface of the first capillary and having an open flat distal end face, the distal end face of the first capillary and the distal end face of the second capillary each extending distally beyond the distal end surface of the laser fiber; and

an outer cover cap coupled to and disposed outside the second capillary, the outer cover having a side opening and a portion distal of the side opening that surrounds the second capillary, wherein the outer cover cap includes an internal planar surface abutting the distal end face of the first capillary and the distal end face of the second capillary.

8. The apparatus of claim 7 , wherein at least one of an entirety of the outer surface of the first capillary component is heat-fused to the second capillary component or an entirety of the inner surface of the first capillary component is heat-fused to the outer surface of the optical fiber.

9. The apparatus of claim 7 , wherein the outer surface of the first capillary component is heat-fused to the second capillary component at a first region, and the outer surface of the first capillary component is heat-fused to the second capillary component at a second region noncontiguous with the first region.

10. The apparatus of claim 7 , wherein the first capillary component has a dopant profile different than a dopant profile of the second capillary component.

11. The apparatus of claim 7 , wherein the first capillary component has an index of refraction that is different than an index of refraction of the optical fiber, and the index of refraction of the first capillary component is substantially equal to an index of refraction of the second capillary component.

12. The apparatus of claim 7 , wherein the laser radiation is emitted from a Ho:YAG source, Nd:YAG source, a semiconductor laser diode, or a laser source having a non-linear crystal element.

13. The apparatus of claim 7 , wherein the fiber is a low hydroxyl fiber.

14. The apparatus of claim 7 , wherein the first capillary and the second capillary are made of silica-based material and the outer cover cap is metallic or made of polymer-based material.

15. An apparatus, comprising: a first capillary extending along a longitudinal axis and having an inner surface and an open distal end, the open distal end of the first capillary having a flat distal end face perpendicular to the longitudinal axis;

an optical fiber disposed inside of the first capillary, the inner surface of the first capillary being heat-fused with an outer surface of the optical fiber, the optical fiber having an angled distal end surface configured to reflect electromagnetic radiation propagated along a longitudinal axis of a distal end portion of the optical fiber in a lateral direction through the inner surface of the first capillary;

a second capillary disposed outside of the first capillary component, the second capillary having a tubular construction open at a proximal and distal end, the distal end of the second capillary having an open flat distal end face, wherein the distal end face of the first capillary and the distal end face of the second capillary extend distally beyond the distal end surface of the optical fiber; and

an outer cover cap coupled to and disposed outside the second capillary, wherein the outer cover cap includes an internal planar surface abutting the distal end face of the first capillary and the distal end face of the second capillary.

16. The apparatus of claim 15 , wherein the distal end faces of the first and second capillary components include coterminous flat ends.

17. The apparatus of claim 16 , wherein the outer cover includes a planar inner surface abutting the coterminous flat ends of the first and second capillary components.

18. The apparatus of claim 12 , wherein the electromagnetic radiation is emitted from a Ho:YAG source, Nd:YAG source, a semiconductor laser diode, or a laser source having a non-linear crystal element.

19. The apparatus of claim 15 , wherein the fiber is a low hydroxyl fiber.

20. The apparatus of claim 15 , wherein the first capillary and the second capillary are made of silica-based material and the outer cover cap is metallic or made of polymer-based material.