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Mirror design v1

[!NOTE] For the first pass, we will use a PVD sputter system with TiO2 (n~2.1-2.4) and SiO2 (n~1.45)

Quarter-wave DBR

You pick a design wavelength λ₀ and make each layer optical thickness λ₀/4:

$$t_L = \lambda_0 / (4 n_L)$$ $$t_H = \lambda_0 / (4 n_H)$$

How many pairs?

Rule of thumb at normal incidence on a good substrate:

With SiO₂ (1.45) / TiO₂ (~2.2):

  • ~8–10 pairs: already “very mirror-like” (often >99.5% if low loss)

  • ~12–16 pairs: pushes toward >99.9% if absorption/scatter are low