Variable ring beam generator

1 . An optical assembly, comprising:

an input fiber to provide a beam;

a process fiber comprising a ring-shaped outer core surrounded by a cladding;

a first beam shifter arranged to receive the beam from the input fiber and to shift the beam spatially to illuminate the ring-shaped outer core of the process fiber;

a second beam shifter arranged to receive the beam from the first beam shifter and to add skew to the beam that is launched into the ring-shaped outer core of the process fiber; and

a graded index fiber coupled between the first beam shifter and the second beam shifter,

wherein the graded index fiber comprises multi-bend components that are configured to form bends in the graded index fiber in two dimensions or three dimensions, and

wherein the bends have a bend period matched to or nearly matched to a pitch of the graded index fiber.

2 . The optical assembly of claim 1 , wherein the beam leaving the process fiber is a ring-shaped beam with a diameter that corresponds to an inner diameter of the cladding and a maximum thickness that corresponds to a thickness of the ring-shaped outer core.

3 . The optical assembly of claim 1 , wherein the beam leaving the process fiber is a ring-shaped beam with a thickness that is based on a magnitude of the skew added to the beam.

4 . The optical assembly of claim 3 , wherein the thickness of the ring-shaped beam leaving the process fiber is less than a thickness of the ring-shaped outer core.

5 . The optical assembly of claim 1 , wherein the beam leaving the process fiber has a larger beam parameter product than the beam provided by the input fiber.

6 . The optical assembly of claim 1 , wherein the skew added to the beam causes the beam to have a larger power density at outside edges of the ring-shaped outer core.

7 . The optical assembly of claim 1 , wherein a length scale over which an intensity of the beam changes from a maximum to a minimum is based on a magnitude of the skew added to the beam.

8 . The optical assembly of claim 1 , wherein the process fiber further comprises a center core surrounded by the ring-shaped outer core, the center core having a higher index than the ring-shaped outer core surrounding the center core.

9 . An optical assembly, comprising:

an input fiber to provide a beam;

a process fiber comprising a ring-shaped outer core surrounded by a cladding; and

a graded index fiber, coupled between the input fiber and the process fiber, arranged to receive the beam from the input fiber and to transmit the beam into the ring-shaped outer core of the process fiber,

wherein the graded index fiber includes a beam shifter arranged to add skew to the beam that is transmitted into the ring-shaped outer core of the process fiber,

wherein the graded index fiber comprises multi-bend components that are configured to form bends in the graded index fiber in two dimensions or three dimensions, and

wherein the bends have a bend period matched to or nearly matched to a pitch of the graded index fiber.

10 . The optical assembly of claim 9 , wherein the beam leaving the process fiber is a ring-shaped beam with a diameter that corresponds to an inner diameter of the cladding and a maximum thickness that corresponds to a thickness of the ring-shaped outer core.

11 . The optical assembly of claim 9 , wherein the beam leaving the process fiber is a ring-shaped beam with a thickness that is based on a magnitude of the skew added to the beam.

12 . The optical assembly of claim 9 , wherein the skew added to the beam causes the beam to have a larger power density at outside edges of the ring-shaped outer core.

13 . The optical assembly of claim 9 , wherein a length scale over which an intensity of the beam changes from a maximum to a minimum is based on a magnitude of the skew added to the beam.

14 . The optical assembly of claim 9 , wherein the graded index fiber is spliced to the input fiber at an offset that causes the beam received from the input fiber to be transmitted into the ring-shaped outer core of the process fiber.

15 . The optical assembly of claim 9 , further comprising:

one or more free space optics having one or more of a controlled position or a controlled motion to transmit the beam into the ring-shaped outer core of the process fiber.

16 . An optical assembly, comprising:

an input fiber to provide a beam;

a process fiber comprising a single core surrounded by a cladding;

one or more resonant beam shifters, coupled between the input fiber and the process fiber, to add skew to the beam such that the beam has a ring-shaped intensity distribution at an exit from the single core of the process fiber; and

a graded index fiber that comprises multi-bend components that are configured to form bends in the graded index fiber in two dimensions or three dimensions,

wherein the bends have a bend period matched to or nearly matched to a pitch of the graded index fiber.

17 . The optical assembly of claim 16 , wherein the beam at the exit from the single core of the process fiber has a diameter that corresponds to an outer diameter of the cladding and a thickness that is based on a magnitude of the skew added to the beam by the one or more resonant beam shifters.

18 . The optical assembly of claim 16 , wherein the skew added to the beam increases a divergence angle of the beam into the process fiber.

19 . The optical assembly of claim 16 , wherein the skew added to the beam causes the beam to have a larger power density at outside edges of the single core.

20 . The optical assembly of claim 1 , wherein the bend period matching or nearly matching to the pitch of the graded index fiber is based on a deviation between the bend period and the pitch of the graded index fiber satisfying a threshold value.