  We demonstrate an effective control of nonlinear interactions of lasing modes
in a semiconductor microdisk cavity by shaping the pump profile. A target mode
is selected at the expense of its competing modes either by increasing their
lasing thresholds or suppressing their power slopes above the lasing threshold.
Despite of strong spatial overlap of the lasing modes at the disk boundary,
adaptive pumping enables an efficient selection of any lasing mode to be the
dominant one, leading to a switch of lasing frequency. The theoretical analysis
illustrates both linear and nonlinear effects of selective pumping, and
quantify their contributions to lasing mode selection. This work shows that
adaptive pumping not only provides a powerful tool of controlling the nonlinear
process in multimode lasers, but also enables the tuning of lasing
characteristic after the lasers have been fabricated.
