Set of slides can be found {{:et_update_2017:coating_update_et_meeting_glasgow_9_17_2.pdf|here}}


Open questions / other approaches:

  * Can we get aSi-based coatings <1ppm absorption?

  * 120 K operation? Some more work needed. Silica loss potentially lower than at 10 / 20 K (depending on annealing state). Cooling by radiation, less limited by heat extraction. Less TN benefit from cooling. 

  * 2um may allow use of a-Ge coatings – higher index than aSi, thinner coatings. What is loss, absorption?

  * Crystalline coatings still of interest (both AlGaAs and AlGaP) – may be scalable to large diameters on the timescale of ET? Similar potential TN reduction to aSi/SiN. AlGaAs already has <1ppm absorption.

  * Nano-layer coatings to suppress crystallisation and enable higher heat-treatment temperatures May be useful for squeezing best possible performance out of amorphous oxide coatings