Systems and methods for diffractive coherent laser combining
This disclosure provides systems, methods, and apparatus related to optical systems. In one aspect, a method includes: generating a plurality of laser beams; receiving the plurality of laser beams at the point at a diffractive optical element, the diffracting optical element diffracting the plurality of laser beams to generate a plurality of output laser beams including a central laser beam and a plurality of side laser beams; measuring a power of at least two of the plurality of output laser beams generated by the diffractive optical element; determining a phase error in laser beams of the plurality of laser beams from the power of the at least two of the plurality of output laser beams; and changing the phase N−1 laser beams of the plurality of laser beams, with N being a number of the plurality of laser beams.
1. An optical system comprising:
an optical source operable to generate a plurality of laser beams, each laser beam of the plurality of laser beams being a continuous-wave laser beam;
a plurality of phase shifters, each phase shifter operable to shift a phase of one of the plurality of laser beams generated by the optical source;
a diffractive optical element, the diffractive optical element operable to receive the plurality of laser beams and to diffract the plurality of laser beams to generate a plurality of output laser beams including a central laser beam and a plurality of side laser beams;
a detection device operable to measure a power of at least two of the plurality of output laser beams; and
a control system operable to determine, using a deconvolution method, a phase error in a laser beam of the plurality of laser beams from the power of the at least two of the plurality of output laser beams, and operable to direct N−1 phase shifters of the plurality of phase shifters to change a phase laser beams of the plurality of laser beams to increase a power of the central laser beam, with N being a number of the plurality of laser beams generated by the optical source.
2. The optical system of claim 1 , wherein the detection device comprises a camera or a photodiode array.
3. The optical system of claim 1 , wherein the optical source comprises a plurality of optical sources.
4. The optical system of claim 1 , wherein the diffractive optical element comprises a transmissive optical element.
5. A method comprising:
(a) generating a plurality of laser beams, each laser beam of the plurality of laser beams being a continuous-wave laser beam, the plurality of laser beams being coherent, each laser beam of the plurality of laser beams having a phase, and each laser beam of the plurality of laser beams converging at a point;
(b) receiving the plurality of laser beams at the point at a diffractive optical element, the diffractive optical element diffracting the plurality of laser beams to generate output laser beams including a central laser beam and a plurality of side laser beams;
(c) measuring a power of at least two of the plurality of the plurality of output laser beams generated by the diffractive optical element;
(d) determining, using a deconvolution method, a phase error in laser beams of the plurality of laser beams from the power of the at least two of the plurality of output laser beams; and
(e) changing the phase of N−1 laser beams of the plurality of laser beams generated in operation (a) to increase a power of the central laser beam, with N being a number of the plurality of laser beams generated in operation (a).
6. The method of claim 5 , wherein laser beams of the plurality of laser beams are arranged in a one-dimensional array or a two-dimensional array prior to converging at the point.
7. The method of claim 5 , wherein the power of the central laser beam is maximized.
8. The method of claim 5 , wherein a power of each laser beam of the plurality of laser beams is about 0.1 milliwatts to 10 kilowatts.
9. The method of claim 5 , wherein the measuring the power is performed with a camera or a photodiode array.
10. The method of claim 5 , wherein the diffractive optical element comprises a transmissive optical element.
11. The method of claim 5 , wherein the plurality of laser beams is generated by a single laser beam passing through a beam splitter.
12. The method of claim 5 , wherein the plurality of laser beams is generated by a plurality of optical sources.
13. The optical system of claim 1 , wherein the plurality of phase shifters comprise fiber phase shifters or free space phase shifters.
14. The optical system of claim 1 , wherein the power of the central laser beam is maximized.
15. The optical system of claim 1 , wherein a power of each laser beam of the plurality of laser beams is about 0.1 milliwatts to 10 kilowatts.
16. The optical system of claim 1 , further comprising:
a beam splitter, the beam splitter operable to generate the plurality of laser beams from a single laser beam from the optical source.
17. The optical system of claim 1 , further comprising:
a plurality of amplifiers, wherein each amplifier is operable to amplify one of the plurality of laser beams from each of the phase shifters; and
a plurality of collimators, wherein each collimator is operable to collimate one of the plurality of laser beams from each of the amplifiers.
18. The optical system of claim 17 , wherein a plurality of optical fibers transport each laser beam of the plurality of laser beams from the plurality of amplifiers to the plurality of collimators.
19. The optical system of claim 1 , further comprising:
a beam splitter, the beam splitter operable to direct the plurality of output laser beams to the detection device.
20. The optical system of claim 1 , wherein the control system includes a field-programmable gate array (FPGA), a digital-to-analog converter (DAC), and piezoelectric amplifiers.