Intensity-modulating characteristics of a laser diode subject to optical injection

We have found that the optical power of a laser diode does not change with the injected light intensity that is modulated when its injection current is at some specified values. The amplitude of optical power change of the LD varies periodically with the increase of the injection current. It is made clear through the theoretical analysis that these phenomena are caused by gain compression and interband carrier absorption of the LD that depend on the longitudinal mode competition, bandgap-shrinkage effects, thermal conduction, and so on. Our experimental results make it get easy to eliminate optical power change of LDs. We only need to choose a proper value of the injection current.