The Wave Equation, Beam Envelopes node is the main node for the Electromagnetic Waves, Beam Envelopes interface. The electric field is factorized into the product
where n is the refractive index and the wave number of free space
k0 is defined as
Here c0 is the speed of light in vacuum.
When solving the equations as an eigenfrequency problem the eigenvalue is the complex eigenfrequency λ = −jω + δ, where
δ is the damping of the solution. The Q-factor is given from the eigenvalue by the formula