Previous to the deposition of the Er:Al2O3 active content, the coupling circuit, i.e., the strip waveguides, the manner changeover tapers and the mode converters had been protected which has a 800?nm thick layer of hydrogen silsesquioxane (HSQ, n?~1.45) to stop their coating Along with the Lively material, as shown in Fig. 1. The HSQ cladding was