4. ATTENUATION 4.1 Classification 4.2 Intrinsic Losses

Presentación del tema: "4. ATTENUATION 4.1 Classification 4.2 Intrinsic Losses"— Transcripción de la presentación:

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

2 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)

3 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 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

5 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)

6 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)

7 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)

8 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)

9 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

10 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)