The preceding calculations have all ignored the effects of surface reflections and bulk absorption in the optical materials, both of which ZEMAX has detailed models of. In both the POP and Single Mode Fiber calculations, the switch Use Polarization in the Settings turns on the Polarization calculation so that surface transmission effects and volume absorption can be accounted for.

Re-open the after POP.zmx sample file and in the settings of both the Fiber Coupling calculation and POP calculation select "Use Polarization". Save the settings. Then click on General > Polarization and define the incident polarization to be linear in y:

As a result, the fiber coupling calculation from POP and FICL drop to around 86%. Note the change is in the system efficiency (energy transport) rather than in the mode coupling: the polarization effects are too slow as a function of angle for the mode shape to be changed, although a more extreme system may show changes because of this.

Under Tools > Coatings > Add Coatings to All Surfaces, add a single-layer MgF₂ coating to all glass surfaces:

With this coating in place, note that the coupling efficiencies improve

	No Polarization	Polarization, No coatings	Polarization and AR coatings	Polarization and HEAR1 coatings
POPD	99%	86%	92%	98%