Fiber-based output couplers for wavelength beam combining laser systems
View Patent ↗In various embodiments, wavelength beam combining laser systems incorporate optical fibers and partially reflective output couplers or partially reflective interfaces or surfaces utilized to establish external lasing cavities.
1. A laser system comprising:
an array of beam emitters each emitting a beam;
focusing optics for focusing the beams toward a dispersive element;
the dispersive element for receiving and dispersing the focused beams, thereby forming a multi-wavelength beam;
an optical fiber for receiving the multi-wavelength beam; and
disposed within or on the optical fiber, a partially reflective interface for receiving the multi-wavelength beam, reflecting a first portion thereof back toward the dispersive element, and transmitting a second portion thereof as an output beam composed of multiple wavelengths.
2. The laser system of claim 1 , further comprising an end cap attached to the optical fiber, the partially reflective interface being disposed between the end cap and the optical fiber.
3. The laser system of claim 2 , wherein (i) the end cap comprises a first material, (ii) the optical fiber comprises a second material, and (iii) the first material is different from the second material.
4. The laser system of claim 3 , wherein the first material comprises sapphire and the second material comprises glass.
5. The laser system of claim 2 , wherein the partially reflective interface comprises a coating applied to a surface of the end cap and/or a surface of the optical fiber.
6. The laser system of claim 1 , wherein (i) the partially reflective interface is disposed (a) within the optical fiber, and (b) between a portion of the optical fiber and a void disposed within the optical fiber, and (ii) a cross-section of the void is smaller than a cross-section of the optical fiber.
7. The laser system of claim 6 , wherein the void comprises therewithin air or vacuum.
8. The laser system of claim 1 , wherein (i) the optical fiber comprises first and second optical fiber portions joined together, and (ii) the partially reflective interface is disposed between the first and second optical fiber portions.
9. The laser system of claim 8 , further comprising a mode field adaptor or a fiber taper disposed optically downstream of the partially reflective interface.
10. The laser system of claim 8 , wherein (i) the first optical fiber portion comprises a core region optically upstream of the partially reflective interface, (ii) the second optical fiber portion comprises a core region optically downstream of the partially reflective interface, and (iii) a diameter of the core region of the second optical fiber portion is larger than a diameter of the core region of the first optical fiber portion.
11. The laser system of claim 6 , wherein the void comprises vacuum therewithin.
12. The laser system of claim 6 , wherein the void comprises a bubble disposed within the optical fiber.
13. The laser system of claim 1 , wherein the dispersive element comprises a diffraction grating.
14. The laser system of claim 1 , wherein the focusing optics comprises one or more cylindrical lenses, one or more cylindrical mirrors, one or more spherical lenses, and/or one or more spherical mirrors.
15. The laser system of claim 1 , further comprising, disposed between the array of beam emitters and the focusing optics, second optics for rotating the beams emitted by the array of beam emitters.
16. The laser system of claim 5 , wherein the coating has a reflectivity to at least one wavelength of the multi-wavelength beam ranging from about 1% to about 10%.
17. The laser system of claim 5 , wherein the coating comprises one or more metallic layers.
18. The laser system of claim 5 , wherein the coating comprises one or more dielectric layers.