4. ATTENUATION 4.1 Classification 4.2 Intrinsic Losses 4.3 Extrinsic Losses 4.4 Nonlinear Effects 4.5 Total Losses

4.1 CLASSIFICATION 1st Classification 2nd Classification Intrinsic: inherent to the material (unavoidable) Extrinsic: due to manufacture processes (avoidable) 2nd Classification Absorption: photons’ energy is taken up by matter Scattering: photons are deviated from a straight trajectory Radiation: light is radiated outside 3rd Classification Linear Processes: spectrum maintains its shape Nonlinear Processes: spectrum’s shape changes PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.2 INTRINSIC LOSSES (I) Rayleigh Scattering Linear, intrinsic, scattering Due to refractive index thermal fluctuations Inversely proportional to 4 PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.2 INTRINSIC LOSSES (II) Why Is the Sky Blue? We see blue light from Rayleigh scattering off the air (L) L  -4 blue (f, )  L red (f, )  L Why is the sunset reddened? SUN PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial) SUN

4.2 INTRINSIC LOSSES (III) Intrinsic Absorption Ultraviolet absorption Interaction photon/atom Photon excites an electron (jumps to conduction band) It decreases when λ is higher Infrared absorption Interaction photon/molecule Photon energy is converted into atomic vibration It increases when λ is higher Intrinsic losses limit available fiber windows PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.2 INTRINSIC LOSSES (IV) Intrinsic Losses Graphic PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.3 EXTRINSIC LOSSES Absorption Losses Fiber Bending Losses by ion resonance. E.g. OH─ (→water) Water is extremely hard to eliminate Absorption peaks: 1380, 950, 720 nm Purity requirements: 1 ion per million → 1 dB/km more (950 nm) Fiber Bending More rays escape into the cladding Limits bend radius Criterion: r  10 (: total diameter, including coating) PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.4 NONLINEAR EFFECTS Fundamentals They limit system capacity Causes Interactions between photons and fiber Refractive index varies with power (power density) Types Four-Wave Mixing: several waves mix → intermodulation products Stimulated Brillouin Scattering: mechanical (acoustic) vibrations Stimulated Raman Scattering: molecular vibrations Management Several wavelengths will mix (FWM) Singlemode (small core) has higher power densities Maintain power levels under threshold (3 mW avoids nonlinearities) PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)

4.5 TOTAL LOSSES (I) Total Losses Calculation PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial) TOTAL LOSSES MINIMUM AT 1550 nm

4.5 TOTAL LOSSES (II) Attenuation Windows PESO - Menos de la décima parte que coaxial INCONVENIENTES - No es capaz de llevar la alimentación (como hace el coaxial)