A highly confusing term is gain. For example, the sentence "the gain of a system should be doubled", without context, means close to nothing. It may mean that the ratio of the output voltage of an electric circuit to the input voltage should be doubled. It may mean that the ratio of the output power of an electric or optical circuit to the input power should be doubled. It may mean that the gain of the laser medium should be doubled, for example, doubling the population of the upper laser level in a quasi-two level system (assuming negligible absorption of the ground-state).
A highly confusing term is gain. For example, the sentence "the gain of a system should be doubled", witho.ut context, means close to nothing. It may mean that the ratio of the output voltage of an electric circuit to the input voltage should be doubled. It may mean that the ratio of the output power of an electric or optical circuit to the input power should be doubled It may mean that the gain of the laser medium should be doubled, for example, doubling the population of the upper laser level in a quasi-two level system (assuming negligible absorption of the ground-state).