Previous to the deposition with the Er:Al2O3 Energetic content, the coupling circuit, i.e., the strip waveguides, the mode changeover tapers plus the method converters have been protected using a 800 nm thick layer of hydrogen silsesquioxane (HSQ, n ~1.45) to prevent their coating with the Energetic product, as shown in https://jacquesb075uag0.wikiworldstock.com/user