Coherent light generators – Particular pumping means – Pumping with optical or radiant energy
Patent
1992-03-06
1993-04-27
Ullah, Akm E.
Coherent light generators
Particular pumping means
Pumping with optical or radiant energy
372 97, H01S 3093
Patent
active
052068749
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a solid-state laser comprising a resonator, at least one laser amplification volume arranged in the resonator and a pump means for exciting the laser amplification volume.
In all hitherto known solid-state lasers such as optically pumped solid-state rod lasers or semiconductor lasers, problems arise with the controlling of the dissipation heat.
when unfiltered light from gas-discharge lamps is used as pumping power source, one has to assume that, for example, in the case of the Nd laser approximately three times the obtainable laser power will remain as heat in the solid-state rod. This heat causes temperature gradients which in individual cases result in breakage of the crystals, but at any rate in optical deformations. For these reasons, today's solid-state lasers are subject to a power limit which does not permit multi-kilowatt operation if the beam quality is still to be good and adaptable to changing operating conditions.
A further problem of the known optically excited solid-state lasers resides in the design of the excitation light source. With a total laser efficiency of a few percent, the excitation lamps have to convert up to 100 kW if the laser is to generate a few kW laser power. This power concentration can only take place in larger volumes and surfaces. On the other hand, the emitted light has to be directed at the active medium. The latter should absorb the excitation light as completely as possible, which requires a layer thickness of several mm.
The same problems occur with the semiconductor laser where, in addition, a laser-active semiconductor layer region cannot be of optional, large-volume configuration if purposeful laser amplification is to be achieved.
In view of these disadvantages of the prior art, the object underlying the invention is to so improve a solid-state laser of the generic kind that it is suitable for generating high power.
This object is accomplished in accordance with the invention in a solid-state laser comprising a laser-active unit with a laser amplification volume extending in a first direction in a solid, a pump means associated with the laser amplification volume for exciting it and a resonator with an excitation section which is arranged between its resonator mirrors and in which a beam extends in a direction of propagation and thereby penetrates in the laser amplification volume in the first direction, by at least two excitation sections being provided, each having one laser amplification volume, by the beams of the excitation sections extending in spaced relation to one another, by the resonator having a coupling section containing a coherent joint beam of the resonator, the cross-section thereof being comprised of several partial beams, and by an optical element being arranged between the coupling section and each excitation section for imaging one of the partial beams of the joint beam into one of the beams extending in spaced relation to one another in the excitation sections.
The advantage of the inventive solution is that with this solution it is made possible for the beams of the individual excitation sections to be imaged into partial beams which, for their part, add up in cross-section and thereby produce a joint beam in which there is coherent radiation over all of the partial beams. In this way, the amplification of at least two laser amplification volumes can be used to generate a joint beam which as such is coherent and has high laser power.
With the invention solution, it is not absolutely necessary for all of the partial beams of the joint beam to be imaged into a beam of one of the excitation sections. It is also adequate for only individual ones of the partial beams of the joint beam to be imaged into a beam of one of the excitation sections while the other partial beams of the joint beam do not experience such imaging. In any case, it is, however, necessary for all of the partial beams to be coherent among one another in the joint beam.
In accordance with the invention, it is particularly advantageous for the partial
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Deutsche Forschungsanstalt
Lipsitz Barry R.
Ullah Akm E.
Wise Robert E.
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