Understanding Optical Modulation Amplitude (OMA)

This article explains the definition of Optical Modulation Amplitude (OMA) as used in the optical domain. We’ll also cover the formula or equation used to calculate OMA.

Definition of OMA

• OMA refers to the difference between two power levels of an optical signal generated by a laser source.
• It is typically expressed as a peak-to-peak value and measured in milliwatts (mW).

Figure 1: A stressed eye diagram showing the OMA

The figure above illustrates OMA within a stressed eye diagram of an optical signal.

OMA Formula or Equation

Optical Modulation Amplitude (OMA) can be calculated using either of the following formulas:

Figure 2: OMA Formulas

Here’s a breakdown of the terms used:

• Pav is the average power of the optical signal.
• re is the extinction ratio of the optical signal.
• P1 represents the power level when the optical light source is in the “ON” state.
• P0 represents the power level when the optical light source is in the “OFF” state.

The following relationships are also important:

• Pav = (P1 + P0) / 2
• re = P1 / P0

Essentially, OMA provides a measure of the optical power variation between the ‘on’ and ‘off’ states of a laser source and is crucial for characterizing the quality of an optical signal.