We have triggered transverse instabilities by injecting a CW monochromatic (10MHz) beam into a vertical-cavity surface-emitting laser (VCSEL). With increased injection current, the TEM00 transverse mode changes to a combination of TEM00, TEM*01 (doughnut), and TEM11. Various transverse modes patterns can then be produced by frequency tuning the injection. Interferometrically analyzing these patterns shows that some zero-field points are field vortices. The position of the vortex depends on injection frequency, power, polarization, and input position. The circulation of the phase gradient on any loop that encloses the vortex core is equal to 2kπ, with k (equal to one in our experiment) representing the order of the vortex, or topological charge.