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

$\text{OMA}=P_1-P_0$

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 $P_{\text{av}}=(P_1+P_0)/2$ and the extinction ratio $r_e=P_1/P_0$

$\text{OMA}=2P_{\text{av}}\frac{r_e-1}{r_e+1}$

In the limit of a high extinction ratio, $\text{OMA}\approx 2P_{\text{av}}$. 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.

External links

• OMA presentation by Optillion, New Orleans, September 2000