Fourier-optical selection of higher order transverse modes in broad area lasers.
A partially and a highly antire ection coated broad area laser are operated in an external cavity Fourier-optical 4f set-up to experimentally investigate transverse mode selection. The external cavity consists of a lens and a spatial frequency filter. Running freely the lasers show non-stationary filamentation. Placing the spatial filter unit directly onto the optical axis gives cw fundamental mode operation and a transverse shift of the spatial filter in the plane of the active region allows for selective excitation of higher order modes.
Wolff
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S
Messerschmidt
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D
Fouckhardt
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H