Optical modulation amplitude

In telecommunications, optical modulation amplitude (OMA) is the difference between two optical power levels, of a digital signal generated by an optical source, e.g., a laser diode.

It is given by

where P₁ is the optical power level generated when the light source is "on," and P₀ is the power level generated when the light source is "off." The OMA may be specified in peak-to-peak mW.

The OMA can be related to the average power P av = ( P 1 + P 0 ) / 2 and the extinction ratio r e = P 1 / P 0

In the limit of a high extinction ratio, OMA ≈ 2 P a v . However, OMA is often used to express the effective usable modulation in a signal when the extinction ratio is not high and this approximation may not be valid.