Enter the phase constant and the wavenumber into the Calculator. The calculator will evaluate the Effective Refractive Index. 

Effective Refractive Index Formula

ERI = B *w/(2pi)


  • ERI is the Effective Refractive Index ()
  • B is the phase constant
  • w is the wavenumber

To calculate Effective Refractive Index, multiply the phase constant by the wavenumber, then divide by 2 times pi.

How to Calculate Effective Refractive Index?

The following steps outline how to calculate the Effective Refractive Index.

  1. First, determine the phase constant. 
  2. Next, determine the wavenumber. 
  3. Next, gather the formula from above = ERI = B *w/(2pi).
  4. Finally, calculate the Effective Refractive Index.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

phase constant = 34

wavenumber = 1234