Method and apparatus for coherently combining laser emission
View Patent ↗A laser system comprises first and second laser sub-cavities each including a gain medium arranged to produce volume gain gratings. The laser system further includes a beam combiner arranged to combine emission from each cavity and direct emission from one cavity to the other. As a result a stale, phase-locked coherently combined emission system is provided.
1. A laser system, for coherently combining emission from two or more laser cavities, comprising:
two or more laser cavities sharing a common emission output, each cavity including a gain element arranged to produce volume gain gratings; and
a beam combiner arranged to combine emission from each cavity and to return a portion of the emission from each cavity into each of the other cavities.
2. A laser system as claimed in any claim 1 , wherein each of said cavities includes a self-intersecting loop path.
3. A laser system as claimed in claim 2 in which the loop path is formed of a plurality of mirrors.
4. A laser system as claimed in claim 2 , wherein each gain element is provided at an intersection point of the loop path to provide, in operation, the formation of volume gain gratings.
5. A laser system as claimed in claim 1 , further comprising a non-reciprocal transmission element in each loop path.
6. A laser system as claimed in claim 5 , wherein the non-reciprocal transmission element is composed of a pair of polarisers with intermediate placement of a 45 degree Faraday rotator and a half-wave retardation plate.
7. A laser system as claimed in claim 5 , wherein the non-reciprocal transmission element introduces a non-reciprocal phase shift of 180 degrees between the passage of the optical radiation in the one direction in the loop path to the other direction of the loop path.
8. A laser system as claimed in claim 1 , comprising a beam combiner arranged to combine emissions from a first and a second cavity, a second beam combiner arranged to combine emission from a third and a fourth cavity, and a third beam combiner to combine emission of first, second, third and fourth cavity.
9. A laser system as claimed in claim 1 , in which the beam combiner comprises a beam splitter.
10. A laser system as claimed in claim 1 , in which emission from two or more cavities is combined at a common beam combiner comprised of a diffractive optical element.