Occasionally known as 'Gain Flatness', this is a
measure of how much an
amplifiers
gain varies with the
wavelength of
input signal. It is usually expressed in terms of
dB/
m (or
cm,
mm or in
photonics,
nm).
One of the characteristics of a 'perfect' amplifier is that it has a totally flat gain tilt (ie 0 decibels) across all wavelengths. No one has (as of yet) managed to create this mythical piece of hardware, and so the gain tilt of an amplifier is one of the primary determining factors of its useful operating bandwidth.