We demonstrate lasing mode selection in nearly circular semiconductormicrodisks by shaping the spatial profile of optical pump. Despite of strongmode overlap, adaptive pumping suppresses all lasing modes except the targetedone. Due to slight deformation of the cavity shape and boundary roughness, eachlasing mode has distinct emission pattern. By selecting different mode to bethe dominant lasing mode, we can switch both the lasing frequency and theoutput direction. Such tunability by external pump after the laser isfabricated enhances the functionality of semiconductor microcavity lasers.
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