Polarization Beam Combining | previous | next | feedback |
Definition: a technique for combining two polarized laser beams
Polarization beam combining (or polarization coupling) is a simple technique for combining (superimposing) two linearly polarized laser beams. For example, the output beams of two broad area laser diodes, one being vertically polarized and the other one horizontally polarized, can be sent onto a thin-film polarizer such that one of the beams is reflected, the other one transmitted, and both beams then propagate in the same direction. As a result, one obtains an unpolarized beam having the combined optical power of the input beams (disregarding some parasitic losses) and the same beam quality. Accordingly, the brightness is nearly doubled.
This technique is often used e.g. for end pumping of a solid-state laser with an increased power. It works only if the laser crystal can similarly well absorb pump radiation with both polarization directions. This is the case e.g. for Nd:YAG, but not for Nd:YVO4.
Polarization beam combining can not be considered as a method for power scaling, as it is not repeatable: it requires polarized input beams and leads to an unpolarized output beam.
See also: beam combining, brightness, polarization of laser emission
Categories: general optics, methods
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