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Optical density OD0

Doped layers thickness 2l, μm

*Samllsignal absorption α0, cm−1

*passive loss γ, cm−1

*Fe2+ average concentration n0, cm−3

464

1.3

135 ± 15

51

43

0.6 × 1020

422

3.1

165 ± 15

157

27

1.9 × 1020

474

6.2

240 ± 20

242

17

2.8 × 1020