The introduction of gain into an optical medium is most easily accomplished by reversing the sign of the extinction
coefficient. The theoretical expression for reflectance at a simple boundary between a dielectric, lossless incident
medium and a medium with a finite extinction coefficient, however, takes no account of the sign of the extinction
coefficient In such an arrangement, therefore, can the presence of gain possibly result in an enhanced reflectance?
Opinions in the literature differ but tend to find enhancement beyond the critical angle and none below. This study
examines both cases and shows that all results are in fact correct but they are not necessarily stable and it is their
stability, or lack of it, that leads to the different results.