# | 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 |