CML - TM polarization for components

[lukasc-ubc]

• TM GC does not excite the TM mode.
• Y branch missing the TM simulations.

strip waveguide model correctly has TE and TM modes.

other components - what do they do for TM?

[121comeon]

For the TM GC, we are using the Optical S-Parameter element. Currently, its property "Waveguide > modes" is "TM", but it should be " , TM", so that ONA's orthogonal identifier 1 & 2 corresponds to "TE" & "TM".

In general, it is better to use the Optical N Port S-Parameter element, which is clearer and can include multiple modes (though syntax is a bit longer).

[lukasc-ubc]

Fixed the GC CML to have Waveguide > modes = ", TM"

Also updating KLayout PDK:

• added orthogonal_identifier to Laser
• netlist script to use orthogonal_identifier
• created a sample layout for TE and TM.