A semiconductor device is provided that includes an optical feedback structure that is monolithically integrated with a VCSEL device and which extends the speed of the VCSEL device beyond the speed to which it would otherwise be limited due to relaxation oscillation. The optical feedback structure does not rely on light emissions from the VCSEL substrate material to produce optical feedback. Consequently, extension of the bandwidth of the semiconductor device through the use of optical feedback is not limited by the absorption threshold wavelength of the substrate material. Furthermore, because the optical feedback structure does not include the substrate, the ability to use optical feedback to extend the bandwidth of the device is independent of the precision with which the substrate thickness can be controlled.