Control of cavity solitons and inhomogeneity compensation in VCSELs with frequency selective feedback

Cavity solitons (CS) have been demonstrated in VCSELs with feedback from a diffraction grating and display many qualities that are of interest to all-optical processing and telecommunication applications. In a completely homogeneous VCSEL, the formation of CS would not occur spontaneously when increasing current, but could only be excited by an external beam. In the real laser system however the VCSEL is not homogeneous across the aperture. Small micro-scale ´defects´, believed to be refractive index modulation, cover the aperture of the device creating an optically rough surface. These defects coupled with noise allow CS to appear spontaneously by increasing current. A spatial light modulator is used to spatially modulate the external laser diode and inject this beam into the VCSEL.