Microsoft PowerPoint fiberoptic [Compatibility Mode]
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FIBER OPTIC COMMUNICATIONS FIBER OPTIC COMMUNICATIONS Prof. Murat Torlak EE4367 Telecom. Switching & Transmission Optical Fibers Optical Fibers Fiber optics (optical fibers) are long, thin strands of very pure glass about the size of a human hair. They are arranged in bundles called optical cables and used to transmit signals over long distances. Prof. Murat Torlak EE4367 Telecom. Switching & Transmission Fiber Optic Data Transmission Systems Fiber Optic Data Transmission Systems Fiber optic data transmission systems send information over fiber by turning electronic signals into light. Light refers to more than the portion of the electromagnetic spectrum that is near to what is visible to the human eye. The electromagnetic spectrum is composed of visible and near-infrared light like that transmitted by fiber, and all Prof. Murat Torlak EE4367 Telecom. Switching & Transmission near-infrared light like that transmitted by fiber, and all other wavelengths used to transmit signals such as AM and FM radio and television. The electromagnetic spectrum. Only a very small part of it is perceived by the human eye as light. Fiber Optics Transmission Fiber Optics Transmission Low Attenuation Very High Bandwidth (THz) Small Size and Low Weight No Electromagnetic Interference Low Security Risk Elements of Optical Transmission Prof. Murat Torlak EE4367 Telecom. Switching & Transmission Elements of Optical Transmission Electrical-to-optical Transducers Optical Media Optical-to-electrical Transducers Digital Signal Processing, repeaters and clock recovery. Types of Optical Fiber Types of Optical Fiber Multi Mode : (a) Step-index – Core and Cladding material has uniform but different refractive index. (b) Graded Index – Core material has variable index as a function of the radial distance from the center. Single Mode – The core diameter is almost equal to the Prof. Murat Torlak EE4367 Telecom. Switching & Transmission Single Mode – The core diameter is almost equal to the wave length of the emitted light so that it propagates along a single path. Transducers Transducers Electrical-to-Optical Transducers LED - Light Emitting Diode is inexpensive, reliable but can support only lower bandwidth. LD – Laser Diode provides high bandwidth and narrow spectrum. Optical-to-Electrical Transducers PIN Diode - Silicone or InGaAs based p-i-n Diode operates well Prof. Murat Torlak EE4367 Telecom. Switching & Transmission PIN Diode - Silicone or InGaAs based p-i-n Diode operates well at low bandwidth. Avalanche Diode – Silicone or InGaAs Diode with internal gain can work with high data rate. BW Capacity of Fiber Optics BW Capacity of Fiber Optics To give perspective to the incredible capacity that fibers are moving toward, a10-Gbps signal has the ability to transmit any of the following per second: 1000 books 130,000 voice channels 16 high-definition TV (HDTV)channels or 100 HDTV channels Prof. Murat Torlak EE4367 Telecom. Switching & Transmission 16 high-definition TV (HDTV)channels or 100 HDTV channels using compression techniques. (an HDTV channel requires a much higher bandwidth than today’s standard television). Transmission Limitations Transmission Limitations Transmission over fiber is limited by the attenuation and dispersion. Multimode fibers may experience Multimode dispersion: The delayed rays cause pulse spreading Chromatic dispersion: Individual wavelengths may travel at different speeds. Dispersion creates an inherent operational limit defined as Prof. Murat Torlak EE4367 Telecom. Switching & Transmission Dispersion creates an inherent operational limit defined as a bandwidth-distance product (BDP). Bandwidth Bandwidth--Distance Factor & Dispersion Distance Factor & Dispersion Bandwidth-Distance Factor (BDP) & Dispersion km - Gbps D 500 BDP - RZ km - Gbps D 250 BL BDP - NRZ λ λ λ ∆ ≤ ∆ ≤ = Τ 0.25 ≤ ∆ DL Acceptable dispersion Prof. Murat Torlak EE4367 Telecom. Switching & Transmission D λ ∆ where Yüklə 92,45 Kb. Dostları ilə paylaş:
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