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Fiber Optics fundamentals. refracted. q t. q r. q i. incident. reflected. Bending of light ray. q i = angle of incidence q r = angle of reflection q t = angle of refraction. n 2 of medium 2. surface boundary. n 1 of medium 1. refraction index : n = c/v. q t. 1. q i. 2.
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refracted qt qr qi incident reflected Bending of light ray • qi = angle of incidence • qr = angle of reflection • qt = angle of refraction n2 of medium 2 surface boundary n1 of medium 1 refraction index : n = c/v
qt 1 qi 2 3 4 4 3 2 qc = critical angle 1 Snell抯 law n1>n2 n2 n1 n1sinqi = n2sinqt qi = sin-1n2/n1 = qc
Electrical input signal core/cladding chracteristics h2 h1 Multimode stepped index h2 h1 Multimode graded index Single mode Transmission Mode Electrical output signal wavelength : 850,1300 nm h2 h1 wavelength : 1300,1550 nm
Loss in Fibers Transmission 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 0.85m band 1.30m band 1.55m band Attenuation (dB/km) 0 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Wavelength (microns)
Light Source 1200-1600 nm LED 500-1000 nm Laser
Optical fiber comparison MultimodeSingle mode Light source LED/laser Laser Bandwidth >1 GHz/km up to 1000 GHz/km Wavelength 850, 1300 1300,1550 core/cladding 62.5/125* 8/125 Applications LAN, backbone Long distance, Telcom lines Cost expensive more expensive * options with 50/125, 100/140
Typical Fiber Cable Single core Optical cladding Optical core Plastic coating Multicore
Strength Elements Outer Jacket Color Coded Jacket Central Strength Elements fiber Bundles of Fiber Cable Structures cladding core
Fiber in use • Plenums or non-plenums • plenum cable has a fire-resistant jacket, which will not burn, smoke or • give off toxic fumes when expose to heat • Riser cables • cable that runs vertically; e.g. between floors in a building • Indoor or Outdoor • Indoor cable used in building. Outdoor cable used in underground, • directed buries, and aerial applications between building.