Comments on "The noise figure of optical amplifiers"

In a recent letter, Haus proposes a new definition for the noise figure of optical amplifiers, which would be consistent with previous IRE/IEEE standards concerning microwave amplifiers. This new noise figure is signal-independent and is therefore most general, unlike the current one. The purpose of these comments is not to discuss the deep implications of such a possible change in standards, but only to provide additional clarifications on how the two definitions are connected.