High-power, phase-locked, laser arrays
High-power, phased-locked, laser arrays as disclosed herein utilize a system of optical elements that may be external to the laser oscillator array. Such an external optical system may achieve mutually coherent operation of all the emitters in a laser array, and coherent combination of the output of all the lasers in the array into a single beam. Such an “external gain harness” system may include: an optical lens/mirror system that mixes the output of all the emitters in the array; a holographic optical element that combines the output of all the lasers in the array, and an output coupler that selects a single path for the combined output and also selects a common operating frequency for all the coupled gain regions.
1. A method for producing mutually-coherent operation of a plurality of laser emitters, the method comprising:
positioning a lens to receive a respective emitted beam from each of the laser emitters;
positioning a first optical element in a focal plane of the lens such that the first optical element forms a composite beam that contains a respective contribution from each of the emitted beams;
providing a path selector that allows the composite beam to pass therethrough along a selected optical path; and
positioning a three-dimensional optical element to receive the composite beam along the selected optical path, wherein the three-dimensional optical element causes at least a portion of the composite beam to be reflected back along the optical path, such that the reflected portion is fed back into the emitters in such a way that narrowband light from each of the emitters is fed back into all of the emitters,
wherein mutually coherent operation of all the emitters is achieved such that each of the emitters lasers at the same wavelength.
2. The method of claim 1 , wherein the lens is adapted to perform an optical Fourier transform on the emitted beam.
3. The method of claim 1 , wherein the lens is adapted to mix the transformed beams in the focal plane of the lens.
4. The method of claim 1 , wherein the first optical element is a diffractive optical element.
5. The method of claim 1 , wherein the three-dimensional optical element has a Bragg grating formed therein that causes the portion of the composite beam to be reflected back along the optical path.
6. The method of claim 5 , wherein the Bragg grating causes the portion of the composite beam to be reflected back along the optical path through the path selector.
7. The method of claim 1 , wherein the three-dimensional optical element causes the portion of the composite beam to be reflected back along the optical path through the lens.
8. The method of claim 1 , wherein the three-dimensional optical element causes at least a portion of the composite beam to be reflected back along the optical path through the first optical element and the lens.
9. A method for producing mutually-coherent operation of a plurality of light emitters, each of the emitters outputting a respective power and brightness, the method comprising:
mixing respective beams received from each of the plurality of emitters;
forming at least one composite beam containing a respective contribution from each of the emitters; and
feeding back at least a portion of the composite beam containing a respective contribution from each of the emitters in such a way that mutually coherent operation of the plurality of emitters is achieved such that the emitters laser with a phase difference that results in a coherent output beam from the system that effectively combines the powers from each of the emitters.
10. The method of claim 9 , wherein the portion of the composite beam has a selected wavelength, and wherein mutually coherent operation of the plurality of emitters is achieved such that each of the emitters lasers at the selected wavelength.
11. The method of claim 9 , wherein the portion of the composite beam is fed back in such a way that each of the emitters receives narrowband light from every other emitter.
12. The method of claim 9 , wherein the coherent output beam has a brightness that is greater than the brightnesses of the individual emitters.
13. The method of claim 9 , wherein the respective beams are mixed via an optical system.
14. The method of claim 13 , wherein the composite beam is formed via a beam-combining element.
15. The method of claim 14 , wherein a wavelength-selective output coupler receives the composite beam from the beam-combining element.
16. The method of claim 15 , wherein the portion is fed back through the beam-combining element.