Waveguide Y Branch Element



could you please clarify what is the function of a “Waveguide Y Branch” in INTERCONNECT when used to combine 2 optical signals? Isn’t it supposed to add the vectors of the two inputs (0.5 coupling coefficient, 0 phase shift)? For example, if I have 3 optical power meters P1=-3.01189 dBm,angle= -0.13911855 rad, P2=-9.84342183dBm, angle=2.535180104 rad and at the output of the branch I observe P3=-10,0685867, angle=0.1928904821 which is not the sum of P1+P2.


Hi @evachat
It to would be better to consider your Y-branch with input intensities I or input electric fields E.
You want to combine two inpurt signals. There are two inputs and one output. In reality, there is not one output. There are multiple outputs. You can notice it in the following image.

Also, your input signals P1 and P2 have different angles, so they are out-of-phase. As a result, there will be a destructive interference.

Out-of-phase input signals can produce losses.

I hope it could help.


Hi @evachat,

@konslekk is totally right about the functionality of the Y Branch element. The Y Branch adds up the electrical fields but not the intensity of the signals (based on the coupling coefficients), and the equation is (E1+E2)/sqrt(2). The example file optical_y_branch.icp (263.7 KB) has some optical Oscilloscopes connected to the lasers and to the output of the Y Branch and measure the complex transmissions of the signals.

If you look at the complex transmission real and imaginary parts of the signals, they all follow the equation (E1+E2)/sqrt(2).

I hope this could help :slight_smile:


Thanks a lot both of you. It was really helpful.